General Psychology

General Psychology

OpenStax

Lumen Learning

General Psychology

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General Psychology by OpenStax and Lumen Learning is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

About This Course

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This comprehensive, ready-to-adopt Introduction to Psychology course provides thorough coverage of all topics covered in a typical introductory course, including biological psychology, cognitive psychology, developmental psychology, social and personality psychology, and mental and physical health.

The course is organized around the recently recommended model from the American Psychological Association, which encompasses the five psychological domains, or pillars: biological psychology, cognitive psychology, developmental psychology, social and personality psychology, and mental and physical health psychology (see “Strengthening Introductory Psychology: A New Model for Teaching the Introductory Course”).

With the OpenStax Psychology textbook as a foundation, this contains other material curated by Lumen Learning and created by Patrick Carroll of the University of Texas at Austin. The course enriches learning with frequent application, curated videos, selected NOBA content, and interactive learning activities to foster practical skills. Engaging “Psychology in Real Life” features use recent research to help students think critically about experimental design.

What’s New?

We believe in making continual improvements to the course in order to enhance and facilitate student learning. This newest version of the course includes additional Psych in Real Life pages, which provide learners with the opportunity to think deeply about relevant psychological research. These 2019 additions include:

In addition to these new pages, there are also several new assignments options. We have also used data to find areas in the course in need of further clarification or interactives, such as this interactive about reliability and validity.

Acknowledgments

This book has benefited from the contributions of many people, including Stephen Alexander, Madison Barnett, Mike Bonham, Rachael Brown, Alisha Cassani, Adrianna Cluff, Elizabeth Gaudino-Goering, Katie Gibson, Amanda Gill, Jake Hamilton, Kayden Hawkins, Ammon Heinzen, Maya Landgraf, Josh Marshall, Emily Parks, Madelin Pepper, Luke Phillips, Anakin Purser, Blake Rawlings, Celia Scott, Sarah Thompson, Samantha Wendell, and Bridget Wyall.

Course Contents at a Glance

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The following list shows the module-level topics for the course.

Module 1: Psychological Foundations

Module 2: Psychological Research

Module 3: Biopsychology

Module 4: State of Consciousness

Module 5: Sensation and Perception

Module 6: Thinking and Intelligence

Module 7: Memory

Module 8: Learning

Module 9: Lifespan Development

Module 10: Social Psychology

Module 11: Personality

Module 12: Emotion and Motivation

Module 13: Industrial-Organizational Psychology

Module 14: Psychological Disorders

Module 15: Therapy and Treatment

Module 16: Stress, Lifestyle, and Health

Course Learning Outcomes

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The content, assignments, and assessments for this course are aligned to the following learning outcomes. A full list of course learning outcomes can be viewed here: Complete Learning Outcomes.

This course provides coverage for the broad range of learning outcomes that may be taught in introductory psychology courses. With the goal of supporting faculty in the selection of content for their courses, we have organized this course around the 5 pillars, or domains, of psychology as recently recommended by the APA: biological pillar, cognitive pillar, developmental pillar, social and personality pillar, mental and physical health pillar.

Image of building with 5 pillars of psychology: biological, cognitive, developmental, social and personality, mental and physical health.

While we hope that organizing the modules in this fashion proves helpful to faculty, faculty have complete freedom to select and organize modules for their course as they choose, as modules may easily be reorganized.

Biological Psychology Domain

Cognitive Psychology Domain

Developmental Psychology Domain

Social and Personality Psychology Domain

Mental and Physical Health Domain

Faculty Resources

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Faculty Resources Overview

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We’ve seen overwhelming demand for high quality, openly-licensed course materials, including supplemental resources to enrich teaching and learning and to make life easier for instructors. To support this need, we’ve developed and curated faculty resources to use with this course.

Free and Open Supplemental Materials

On the following pages, you will find supplemental resources that are freely available to use with the interactive learning materials for this course. Since these resources are openly licensed, you may use them as is or adapt them to your needs.

Pacing

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The APA encourages introductory psychology instructors to teach the foundations of psychology and to choose at least one topic to cover in depth within each of the five domains of biological psychology, cognitive psychology, developmental psychology, social and personality psychology, and mental and physical health (see “Strengthening Introductory Psychology: A New Model for Teaching the Introductory Course” and “Strengthening the Common Core of the Introductory Psychology Course“). As this introductory course is large and comprehensive, we do NOT recommend teaching all 16 modules in one semester.

Some of the smaller modules that could potentially be combined with other modules include:

The largest modules, which may take even more than one week, include:

The order of the modules may also be rearranged to suit personal preferences. Some like to teach Personality next to Psychological Foundations at the beginning of the course, then jump into Psychological Research and Social Psychology. You can adjust the order of the modules inside your LMS.

Below is a reference table for potential module organization in courses of various lengths.

16 Weeks 14 Weeks 12 Weeks 12-14 Weeks 8 Weeks
All modules covered (not recommended) Possibly includes all modules, or combines select modules from cognitive psychology and social/personality psychology Excludes states of consciousness and select modules from cognitive psychology and social/personality psychology Devote 2 weeks to each of the main psychological domains Focuses on 1 or 2 modules in each domain
Week 1 Psychological Foundations Psychological Foundations Psychological Foundations Psychological Foundations Psychological Foundations AND Psychological Research
Week 2 Psychological Research Psychological Research Psychological Research Psychological Research Biopsychology
Week 3 Biopsychology Biopsychology Biopsychology Domain 1: Biological Psychology Sensation and Perception OR Thinking and Intelligence OR Memory
Week 4 State of Consciousness State of Consciousness Sensation and Perception Domain 1: Biological Psychology Learning
Week 5 Sensation and Perception Sensation and Perception Thinking and Intelligence OR Memory Domain 2: Cognitive Psychology Lifespan Development
Week 6 Thinking and Intelligence Thinking and Intelligence AND/OR Memory Learning Domain 2: Cognitive Psychology Social Psychology
Week 7 Memory Learning Lifespan Development Domain 3: Developmental Psychology Psychological Disorders
Week 8 Learning Lifespan Development Social Psychology Domain 3: Developmental Psychology Therapy and Treatment
Week 9 Lifespan Development Social Psychology Personality OR Emotion and Motivation OR Industrial-Organizational Psychology Domain 4: Social and Personality Psychology
Week 10 Social Psychology Personality Psychological Disorders Domain 4: Social and Personality Psychology
Week 11 Personality Emotion and Motivation AND/OR Industrial-Organizational Psychology Therapy and Treatment Domain 5: Mental and Physical Health
Week 12 Emotion and Motivation Psychological Disorders Stress, Lifestyle, and Health Domain 5: Mental and Physical Health
Week 13 Industrial-Organizational Psychology Therapy and Treatment
Week 14 Psychological Disorders Stress, Lifestyle, and Health
Week 15 Therapy and Treatment
Week 16 Stress, Lifestyle, and Health

PDF

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PDF versions of the primary textbook are available for offline use. While these versions are a convenient alternative for times when students lack Internet access, they do not include interactive content such as simulations, videos, and quizzes. For that reason, the offline versions should be used as a backup rather than as the primary textbook.

You can download a PDF (and other formats) directly from the cover page:

To share these files with your students, copy and paste the information above into your learning management system (Blackboard, Canvas, etc.).

PowerPoints

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A full set of PowerPoint decks is provided for download below. All decks are tightly aligned to the modules in this course. Since they are openly licensed, you are welcome to retain, reuse, revise, remix, and redistribute as desired.

These PowerPoint files are accessible. If you do revise them, make sure to follow these guidelines for creating accessible PowerPoints.

Use this link to download all PowerPoint decks in a single .zip file (40 MB). or the following links for individual modules.

Assignments

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The assignments in this course are openly licensed, and are available as-is, or can be modified to suit your students’ needs. Selected answer keys are available to faculty who adopt Waymaker, OHM, or Candela courses with paid support from Lumen Learning. This approach helps us protect the academic integrity of these materials by ensuring they are shared only with authorized and institution-affiliated faculty and staff.

If you import this course into your learning management system (Blackboard, Canvas, etc.), the assignments will automatically be loaded into the assignment tool, where they may be adjusted, or edited there. Assignments also come with rubrics and pre-assigned point values that may easily be edited or removed.

The assignments for Introductory Psychology are ideas and suggestions to use as you see appropriate. Some are larger assignments spanning several weeks, while others are smaller, less-time consuming tasks. You can view them below or throughout the course.

You can view them below or throughout the course.

Module

Discussion

Assignment

Psychological Foundations Perspectives in Psychology

Explain behavior from 3 perspectives.

Topics in Psychology

Watch a TED talk

Psychological Research Analyzing Research

Describe and discuss a PLOS research article.

Psychology in the News

Compare a popular news article with research article

Biopsychology Using Your Brain

Describe parts of the brain involved in daily activities.

Brain Part Infographic

Create a visual/infographic about a part of the brain

*larger assignment

State of Consciousness Sleep Stages

Describe sleep stages and ways to improve sleep.

Sleep and Dream Journal

Track and analyze sleep and dreams. Record sleep habits and dreams a minimum of 3 days.

*larger assignment, needs introduction at least 1 week prior to due date

Sensation and Perception Cultural Influences on Perception

Demonstrate cultural differences in perception.

*If used in conjunction with the “Perception and Illusions” assignment, this post could ask students to bring in examples/evidence from the illusion task.

Applications of the Delbouef Illusion

Apply Food Lab research and the Delbouef Illusion to recommend plate size and dinner set-up.

Perception and Illusions

Apply an understanding of Martin Doherty’s research on developmental and cross-cultural effects in the Ebbinghaus illusion. Find an illusion, describe it, and explain whether or not it may show cross-cultural effects.

Thinking and Intelligence Thinking about Intelligence

Choose to respond to two questions from a list.

What Makes Smarts?

Describe 3 smart people and analyze what contributes to their intelligence.

Thinking and Intelligence—The Paradox of Choice

Examine an experiment about cognitive overload and decision-making when given many options.

Memory Explaining Memory

Create a mnemonic and explain an early childhood memory.

Study Guide

Apply knowledge from module on memory, thinking and intelligence, and states of consciousness to help a struggling student.

Learning What I Learned

Write examples of something learned through classical, operant, and observational learning.

Conditioning Project

Spend at least 10 days using conditioning principles to break or make a habit.

*requires sufficient time (10 days) of working on changing behavior, and should be introduced with two weeks of advanced notice.

Lifespan Development Stages of Development

Pick an age and describe the age along with developmental theories and if you agree or disagree with the theoretical designations.

Developmental Toys Assignment

Find toys for a child of 6 months, 4 years, and 8 years, then explain theories for the age and why the toys are appropriate.

Social Psychology Thinking about Social Psychology

Pick one question to respond to out of 4 options.

Designing a Study in Social Psychology

Create a shortened research proposal for a study in social psychology (or one that tests common proverbs).

*larger assignment, possibly the largest assignment. Could be broken into multiple parts and given advanced notice.

Personality Personality and the Grinch

Use two of the theories presented in the text to analyze the Grinch’s personality.

Assessing Personality

Take two personality tests then analyze their validity and reliability.

Personality—Blirtatiousness

Examine various types of validity and design a new way to test the validity of the Blirt test.

Emotion and Motivation What Motivates You?

What motivates you to do your schoolwork?

Theories of Emotion

Demonstrate the James-Lange, Cannon-Bard, Schachter-Singer, and cognitive-mediational theories of emotion.

Growth Mindsets and the Control Condition

Take a deeper look at the Carol Dweck study on mindset and analyze how the results may appear different if the control benchmark varied.

Industrial-Organizational Psychology Thinking about Industrial/Organizational Psychology

Pick a favorite I/O topic or give advice on conducting an interview.

KSAs Assignment

Investigate and reflect on KSAs needed for future job.

Psychological Disorders Diagnosing Disorders

Diagnose a fictional character with a psychological disorder.

Disorder At-a-Glance

Research one disorder and create an “At-a-Glance” paper about the main points.

Therapy and Treatment Thinking about Treatment

Choose to respond to one of four questions.

Treating Mental Illness

Describe 3 different treatment methods for the fictional character diagnosed for the “Diagnosing Disorders” discussion.

*This assignment builds off of the discussion assignment in the previous module, in which students “diagnosed” a fictional character with a psychological disorder.

Stress, Lifestyle, and Health Thoughts on Stress and Happiness

Give advice on managing stress or increasing happiness.

Time and Stress Management

Pick from three options to do things related to tracking stress and time management.

*requires advanced noticed

Question Banks

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Note: It is your responsibility to handle question banks and answer keys securely and appropriately to prevent them from being widely available and searchable via the Internet.

Optional Download

This resource contains 16 question banks with a total of 846 multiple choice questions.

Quiz banks are provided as QTI files, a standard format that allows you to import questions, build, and customize quizzes in most learning management systems (Canvas, Blackboard, etc.). These files cannot be opened outside of an LMS.

Quizzes are not provided in written (e.g. MS Word) form in order to preserve the academic integrity of our quiz banks on behalf of everyone using these materials. We adopted this policy after observing how easy it is for quiz banks in written formats to find their way onto websites that promote academic cheating.

Click the name of your LMS to prompt the download of the file.

Once you’ve downloaded the file, visit the Quiz Imports page and click through to the directions for your LMS.

Additional Resources

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Noba Instructor Resources

Click here to visit the Noba website to download the Noba instructor manual.

Noba requests that instructors register and log in to request access to the test bank.

OpenStax Additional Resources

OpenStax, the primary source for openly-licensed materials in this course, requests that instructors register and log in to request access to available instructor resources.

Available instructor resources may include items like:

I Need Help

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Support Documentation

Thumbnail for the embedded element "Getting Started with PressbooksEDU Webinar"

A YouTube element has been excluded from this version of the text. You can view it online here: https://pressbooks.online.ucf.edu/lumenpsychology/?p=39

If you require even further support, please contact UCF Pressbooks Network Manager, Jim Paradiso at james.paradiso@ucf.edu.

Resources: Course Assignments

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Assignment: Foundations of Psychology

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Topics in Psychology

STEP 1: Visit the TED Talks website and search for a talk on the subject matter of psychology. Watch one of the talks that interests you, as long as it is a minimum of 8 minutes in length. At the top of your response, include the title of the TED Talk, the name of the presenter, when it was filmed, along with a link to the video.

STEP 2: In an essay of between 200-400 words, respond to the following:

Criteria Ratings Points
Presents a coherent summary between 200-400 words Writes in clear, descriptive sentences with no or few grammatical errors. Accurately summarizes the information in the TED talk, shares the title and link, and the talk is at least 8 minutes in length. Does not provide enough detail in the summary or contains several grammatical errors. TED talk is possibly too short or not included. Incomplete summary or difficult to understand OR poor choice of TED talk. __/5
Describes interesting points and evidences from the talk Describes interesting and memorable concepts from the talk. Also explains the research, evidence, or data cited by the presenter in the talk. Does not fully describe concepts from the talk or does not reference the evidence demonstrated in the TED talk. Does not describe concepts from the talk and does not explain evidence. __/6
Explains the psychological perspective fitting the presenter Makes the connection between the TED presenter and the field and perspective of psychology that he or she is presenting about. Describes this perspective. Makes a connection with the TED talk and a perspective but does not describe the perspective or demonstrate an understanding of the perspective. Inaccurately or incompletely describes the psychological perspective that fits the TED talk. __/6
Examines further areas of interest Elaborates on other remaining questions for the presenter or about the topic. Does not fully elaborate on other remaining questions for the presenter or about the topic. Does not consider other questions for the presenter or questions about the topic. __/3
Total: __/20

Assignment: Research in Psychology

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Psychology in the News

STEP 1: Find a popular news article from within the past 10 years that reports on the results of a psychological study. This should not be a blog entry, but a published article from a news source such as Time Magazine, The New York Times, Newsweek, NPR, CNN, Fox News, etc. A great place to look is the APA’s Psychology news portal: http://www.apa.org/news/psycport/. Read through the article and ensure that it is descriptive and sufficiently long enough in order to draw conclusions from the original research mentioned.

STEP 2: Go find the psychological study or studies that are mentioned in the news report. Sometimes those are not freely available online, so you may have to track down the original study through your library’s website. You can find these articles within reputable journals, such as the American Journal of PsychologyCognitive PsychologyEmotionJournal of Abnormal PsychologyJournal of Applied PsychologyJournal of Counseling PsychologyJournal of Educational PsychologyJournal of Personality and Social Psychology, and Memory. The study should have been performed within the past 10 years.

STEP 3: Write a paper between 250-500 words that

  • describes and summarizes both articles
  • compares and contrasts the key points, style, and purpose of the news article with that of the research article
  • examines if the news article accurately describes the research
  • includes correct APA citations (both in-text and in a reference page) for both of the articles
Criteria Ratings Points
Finds appropriate news article and writes summary Finds a detailed and relevant news article on a psychological topic, and provides a coherent summary of the article. Does not provide enough detail in the summary or does not find an appropriate news article Poor choice of news article, incomplete summary, or difficult to understand. __/5
Finds appropriate research article and writes summary Finds a detailed and relevant peer-reviewed article on a psychological topic, and provides a coherent summary of the article. Does not provide enough detail in the summary or does not find an appropriate journal article Poor choice of research article, incomplete summary, or difficult to understand. __/5
Compares and contrasts the news and research article and examines accuracy of the news article Compares and contrasts the key points, style, and purpose of the news article with that of the research article Does not fully compare and contrast the key points, style, and purpose of the news article with that of the research article Does not compare and contrast the key points, style, and purpose of the news article with that of the research article __/5
Includes correct APA citations Provides accurate in-text citations AND a reference page for the articles used Does not fully provide accurate in-text citations AND a reference page for the articles used Does not provide accurate in-text citations AND a reference page for the articles used __/5
Total: __/20

Assignment: Biopsychology

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Brain Part Infographic

STEP 1: Pick a part of the brain you learned about in this module that you would like to learn more about. Do some background research and then find at least one journal article that provides more insight into that part of the brain.

STEP 2: Pick some aspect of your research and show it off! Pick out some of the details about the part of the brain, the result from an experiment, the importance of some research, or the pull out some favorite insights, graphs, or charts—whatever you choose (NOTE: You do not have to summarize all of your research). Your objective is to create an interesting visual (think: infographic) so that an outside observer could quickly learn at least three new things by looking at it. It must include at least 2 images (pictures, charts, and graphs all count as images) and some text. Include your references in APA format either at the bottom of the visual or on a separate page.

You should put effort into this assignment, but please do not feel overwhelmed by creating a visual. There are tools out there to make your information look good and presentable that require no skill or knowledge of graphic design. You can think of it as making a simplified “poster” about either a part of the brain or a study that teaches about that part of the brain. You may design the poster in any medium you desire, including Microsoft Word, PowerPoint, Photoshop, or one of the following programs:

STEP 3: Share your creation with the world so that others can benefit from your work! Using either Flickr or Wikimedia Commons, upload your finished product and publish it so that other psychology instructors and students can use your work. Although not required, we strongly recommend uploading and releasing your work with a Creative Commons license.

Criteria Ratings Points
Creates a visual infographic poster on a part of the brain Visual is attractive and interesting. Visual is somewhat attractive and interesting. Visual is not attractive or interesting. __/5
Includes at least two images and text about the part of the brain Visual includes at least two visuals as well as some text Visual partially includes visuals and text Visual does not include at least two visuals as well as some text __/5
Presents at least three pieces of information Includes at least three pieces accurate and informative facts about the part of the brain Partially includes accurate and informative facts about the part of the brain Does not includes at least three pieces accurate and informative facts about the part of the brain __/10
Includes correct APA citations Provides APA citations either on the image or a separate reference page Provides partial or incorrect APA citations either on the image or a separate reference page Does not provide APA citations __/5
Total: __/25

Assignment: Sleep and Dream Journal

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Sleep and Dream Journal

STEP 1: For this assignment, you’ll be keeping track of your sleep habits and your dreams in order to analyze your sleep habits and examine dream theories. To begin, make a copy of this sleep log.

STEP 2: Keep track of your sleep habits and dreams for a MINIMUM of 3 days.

STEP 3: While it’s not guaranteed you will remember your dreams, you can take some steps to help. Begin by telling yourself you want to remember your dream, then print off the sleep/dream journal and have paper and a pen (or your phone) next to your bed right when you wake up. Try to review the dream in your head as soon as you wake up, and consider specifics such as the people involved, the location and setting, the storyline, or how you felt.

STEP 4: Submit your sleep journal and sleep essay based on the following prompt:

Based on your sleep/dream journal and what you have learned about the purpose for dreaming, write a 1-2 page essay (between 250-500 words) about your own sleep habits.

Your essay should include:

  1. An analysis of your sleep habits. Do you go to bed at the same time every night? How many hours a night do you normally sleep?  How could you be a better sleeper? Do you notice any patterns? What concepts from your text might apply to your sleep habits?
  2. An analysis of your dreams. Why do you usually dream? Are there any patterns or re-occurring themes? Is there any consistency between the things you do during the day and the dreams you have? *If you cannot remember your dreams, you can skip this part and spend more time focusing on the steps above and below.
  3. Your conclusion as to what is the MAIN purpose that we dream and why. Consider the theories presented in your readings.
Criteria Ratings Points
Completes sleep/dream log Completes sleep/dream log for at least three days Partially completes sleep/dream log Does not complete sleep/dream log __/6
Analysis of sleep habits Analyzes sleep habits Partially analyzes sleep habits Does not analyze sleep habits __/7
Analysis of dreams and dream theory Analyzes dreams and describes thoughts about the purpose of dreaming Partially analyzes dreams and describes thoughts about the purpose of dreaming Does not analyze dreams or describe thoughts about the purpose of dreaming __/7
Total: __/20

Assignment: Perception and Food

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Applications of the Delbouef Illusion

Which circle below looks bigger?

Two black circles are shown. The circle on the left has another black ring around the circumference of the circle, while the circle on the right does not.

Having already learned about the Ebbinghaus illusion, you were probably right in guessing that the circle with the ring around it appears larger than the non-surrounded circle. This is an example of the Delboeuf illusion, first identified by Belgian philosopher and mathematician Joseph Delbouef in 1887 or 1888. Modern psychologists have tested this illusion in various experiments, including one to determine if eyeshadow makes eyes look bigger (it does), and others to determine if the quantity of food on a plate looks larger if the plate is smaller.

Studies by Koert Van Ittersum and Brian WansinkResearch by Brian Wansink has been called into question following some significant errors and deceptive results presented in his publications. Since 2017, 17 of his papers were retracted and 15 were revised after it came to light that some of the data had been manipulated. at the Cornell Food and Brand Lab have studied the effect of the Delbouef illusion on eating and serving behavior. In several different experiments, they measured if people would take more or less than a typical serving size depending on the size of their plate, the color of the plate, the color of the tablecloth, and how much they knew about the Delboeuf illusion.

Assignment:

Your mom is in charge of providing meals at the upcoming family reunion and she is worried about not having enough linguini alfredo (a white pasta) to serve the entire crew. She wants to ensure that no one takes too much food.

STEP 1: Read through the study, “Plate Size and Color Suggestibility: The Delboeuf illusion’s bias on eating and serving behavior” by Koert Van Ittersum and Brian Wansink. You can find the full article by searching online or using your library’s database.

STEP 2: Give your mom some advice on what size plates she should use, what color they should be, and what color tablecloths she should buy. Read through the study, then explain in a few paragraphs (between 200-400 words) how your mom can utilize of the Delboeuf illusion to minimize her costs at the reunion. Cite specific pieces of evidence (at least four quantitative examples) from the research.

Criteria Ratings Points
Presents a coherent summary of between 200-400 words Clearly writes a few explanatory paragraphs that demonstrate an understanding of the Delboeuf illusion Writing contains many errors or does not demonstrate an understanding of the Delboeuf illusion Writing is unclear and/or does not demonstrate an understanding of the Delboeuf illusion __/5
Recommendations Recommends the correct plate size, color of plate, and color of tablecloths according to the study Makes incorrect recommendations for either the correct plate size, color, or tablecloths Does not make, or incorrectly makes recommendations for the plate size, color, and tablecloths __/10
Evidence from research Includes at least four quantitative examples from the research Includes less than four quantitative examples from the research Does not include quantitative examples from the research __/5
Total: __/20

Assignment: Perception and Illusions

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Background

You learned already about the Ebbinghaus illusion and how it influences a person’s perception of the size of a golf hole. This, and other illusions, do not always work on all people. Psychologists have found that there are cultural influences (amongst other things, like age) that influence whether or not person falls prey to an illusion. Consider the following experiments done by Martin J. Doherty, an English psychologist.

In one study, Doherty presented the Ebbinghaus illusion to children of various ages, and children were asked to identify which center circle appeared bigger. One of the two central circles was always larger, with the difference between the two going from 2% to 18% (in 4% increments). In a control condition, only the central circles were presented—no surrounding context.

Three different images. The first shows two orange circles of similar size. The next shows those two same circles, but surrounded by other circles. The left center circle is surrounded by large circles, and the orange circle on the right is surrounded by smaller circles. The last image shows the reverse of that, with the left image surrounded by small circles, and the right center circle surrounded by large circles.
Figure 1. This is an approximation of the conditions shown in the actual experiment, in which the orange circles on the right are 2% larger than the center circles on the left. Those in the control group were shown the top image, with only two circles. In the experimental group, people were shown either the difference-enhancing image (lower left), in which the right circle generally appears larger because of context or the difference-reducing image (lower right), in which the right circle appears smaller because of context.

Doherty’s 2010 study showed that children under 9 or 10 were less prone to the Ebbinghaus illusion—so they actually answered more accurately than adults, even though they were slightly worse than adults on the control stimuli. The prime take-away from the study is that we learn to use contextual information; the Ebbinghaus illusion is not an innate product of our perceptual systems. Obviously, this also suggests that there is an adaptive benefit in using context: perception of relative size is, in adaptive terms, “better than” (or more useful than) absolute perception.

Doherty’s 2008 study showed cross-cultural differences in the Ebbinghaus illusion, using the same method as in the developmental study. The subjects were adults (grad students and researchers) from Japan and UK. They also compared males and females, though this distinction was explicitly confounded with field of study (males all in STEM-related areas and females in social sciences). They were careful not to make naïve sex-difference claims or naïve field-of-study claims—rather they referred to these groups by their joint characteristics (e.g., male mathematical scientists or female social scientists). They found that Japanese subjects were significantly more influenced by context (i.e., more misled by the surrounding circles) than the UK scientists. In both cultures, female social scientists were more influenced by context than male mathematical scientists. Connecting this back to the developmental study mentioned above, this means the Japanese were more “adult-like” than folks from the UK and female social scientists were more “adult-like” than male mathematical scientists.

Notice that this study fits the “learning” model in explaining the Ebbinghaus effect. Cultural differences are generally due to learning, not to different innate cognitive or perceptual systems. We would expect no Japan/UK difference if the Ebbinghaus illusion is produced by innate perceptual systems (i.e., unaffected by learning). For example, you read in the text about how the Müller-Lyer illusion is also a “learned” illusion, as it does not affect those who live in cultures with less-carpentered worlds.

Assignment

STEP 1: Read through Doherty’s research article, “The context sensitivity of visual size perception varies across cultures,” paying close attention to the ways that context influences perception.

STEP 2: Consider other common illusions, like those shown in the course here, or found online through other sources, such as these websites:

Pick an illusion that stands out to you, then use the illusion to write a few paragraphs responding to the following questions. Use your understanding of sensation and perception and psychological research to support and enhance your response.

  • Describe the illusion. What is is called? What do you find interesting about it? How does it connect to sensation and perception?
  • How does the illusion work? Does it rely on context, as does the Ebbinghaus illusion, or perceptual tricks, as in the Rubin’s vase illusion, or something else altogether?
  • Explain whether or not you think the illusion would show cultural effects, like those shown in Doherty’s research. Why or why not? Would you say that it is a learned illusion? How is it influenced by context? (There is no right answer to this, but use your understanding of Doherty’s experiment to make a hypothesis).
Criteria Ratings
Describe illusion Describes the illusion in detail, including its name, its development, if applicable, and the way it involves sensation and perception. Describes the illusion, but with minimal detail or explanation. Does not describe the illusion __/4
Explains how the illusion works Accurately explains how the illusion works. Partially explains how the illusion works. Does not explain how the illusion works. __/10
Explains cultural effects Writes a hypothesis, with explanation and evidence, about whether or not the illusion may show cultural effects. Response pulls in evidence from Doherty’s research. Creates a hypothesis about cultural effects of the illusion, but without sufficient explanation or supporting evidence from Doherty’s experiment. Does not develop an hypothesis about cultural effects or explain why or why not the illusion may show these effects. __/6
Total: __20

Assignment: Thinking and Intelligence

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What Makes Smarts?

STEP 1: Think about the three smartest people you know. Who are they? In what ways are they smart? What do they do that sets them apart in intelligence?

STEP 2: Write a response between 150-250 words explaining why these people are smart and, based on your readings, what psychological principles contribute to their intelligence. Were they born that way? Which type of intelligence would Gardner say they possess the most of? Are they also creative or do they have high emotional intelligence?

Criteria Ratings Points
Presents a coherent argument of between 150-250 words Clearly writes a few paragraphs of between 150-250 words Writing is unclear or too short or too long Writing is difficult to understand and/or too long or too short or does not present a coherent argument __/4
Characteristics of intelligence Describes characteristics of the three smartest people you know Partially describes characteristics of smart people you know Does not describe the characteristics of the three smartest people you know __/8
Evidence Provides detailed examples from the readings (or elsewhere) to explain the psychological principles that contribute to intelligence Provides some examples to explain the psychological principles that contribute to intelligence Does not provide or incompletely provides an explanation of the psychological principles that contribute to intelligence __/8
Total: __/20

Assignment: Thinking and Intelligence—The Paradox of Choice

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Background

Psychology teaches us that choosing, perceiving, remembering, and other cognitive activities involve complex processes that compete for limited mental resources. The human brain is an amazing thing, but even when that brain is young and working well, it can reveal its limits by slipping up in surprising ways—like forgetting a decision made a few seconds ago just a few seconds later (choice blindness). Other interesting research provides some insight into how our brain’s manage decision-making. Do you think that making a choice puts big demands on our mental processing system? One line of research suggests that it does.

Let’s examine an experiment that was conducted at a small local grocery store by Sheena Iyengar, then a graduate student at Stanford University. She set up a table for tasting jam near the front of the store. Sometimes the table had 6 types of jam; other times there were 24 types.

Iyengar and her colleagues measured two things. First, which condition—6 jams or 24 jams—was more likely to get people to stop and taste the products? And second, which condition—6 jams or 24 jams—produced more sales of the jams that were sampled.

Try It

Take a guess before reading the answers that follow. What percentage of shoppers do you think stopped…

  • when there were 24 jams on the table?
  • when there were 6 jams on the table?
Show Answer

When there were 24 jams on the table, 60% of shoppers stopped. With just 6 jams, 40% of shoppers stopped.

Now, just looking at the people who stopped and sampled some of the jam at the table, which condition led to better sales?

Try It

Take a guess before reading the answers that follow. What percentage of shoppers do you think bought jam…

  • when there were 24 jams on the table?
  • when there were 6 jams on the table?
Show Answer

When there were 24 jams on the table, 3% of shoppers bought jam. With only 6 jams, 30% of shoppers bought jam.

Details of the Study

The experiment took place in a small but popular grocery store near the Stanford University campus, south of San Francisco, California. A tasting booth was set up in the store on two consecutive typical weekends. These customers were invited “come try our Wilkin and Sons jams.” This was a variety of jam that was typically sold in the store. However, the most popular flavors of the jam (e.g., strawberry and raspberry) were not included in the tasting booth set in order to encourage people to try something new. Shoppers were given a $1 off coupon to purchase a jam. The jams were priced between $4 and $6, before discount.

At different times, the booth offered either 6 types of jam or 24 types of jam. Jam was not sold at the tasting booth. If a person wanted to buy jam, he or she had to go to the shelves, find the jam from a set of 28 flavors of the Wilkin and Sons brand, as well as other jellies and jams regularly available. In other words, purchasing on of the jams required the shoppers to make the effort to find a particular jam on the shelves, just as they would on a typical shopping day.

The two experimental conditions in this study are:

  1. A table with 6 jars of jam
  2. A table with 24 jars of jam

A total of 242 customers walked near the booth when there were 24 jars on the table.

A total of 260 customers walked near the booth when there were 6 jars on the table.

Which table do you think had more customers stop and taste the jam? Take a look at the results below.

More people (and a higher percentage) stopped when there were 24 jars on the table than when there were only 6 jars. This suggests that lots of choices captures our attention and draws us in. Interestingly, customers actually tasted about the same number of jams in the two conditions: usually one or two jams.

The real test in this experiment is found in the amount of jam that was sold, either on the same day or within the week that the $1-off coupon was valid.

Which table do you think sold more jam? Take a look at the results below.

Statistically, there is a very strong difference between these two outcomes.

This result is called “the paradox of choice.” You might think that more options leads to greater likelihood that you will find something you like, and consequently you will be more likely to purchase something under those conditions. But Iyengar and Lepper found the opposite. An extensive number of items seemed to shut people down, making them far less likely to make a choice to purchase one item than when their list was very limited. The researchers studied a variety of other choice objects. For example, using a very different setting, they found similar results when people were offered a large or small variety of chocolates. And they found that students were far more likely to choose to write an optional extra-credit essay when offered only 6 topics to choose from than when they were offered 30 topics.

Why would people buy fewer products when they were given more choices?

Assignment

Based on the research you just read about, describe Dr. Iyengar’s experiment with jam. First, identify the following:

Next, write a short description of the methods used to run this experiment. Then, write a paragraph analyzing the results. Spend time answering the question, “Why would people buy fewer products when they were given more choices?” Use your understanding of psychology and decision-making, as well as examples from your own life, to support your argument in explaining the paradox of choice.

Criteria Ratings Points
Identifies hypotheses Correctly identifies the hypotheses of Dr. Iyengar’s experiment Partially identifies the hypotheses of the experiment Incorrectly identifies the hypotheses of the experiment __/3
Identifies independent variables Correctly identifies the IV of Dr. Iyengar’s experiment Partially identifies the IV of the experiment Incorrectly identifies the IV of the experiment __/3
Identifies dependent variables Correctly identifies the DV of Dr. Iyengar’s experiment Partially identifies the DV of the experiment Incorrectly identifies the DV of the experiment __/3
Explains methods and results Summarizes the methods used in the experiment and how it was executed. Correctly summarizes results. Partially describes the methods used in the experiment and the results. Incorrectly describes the methods used in the experiment and the results. __/5
Explains the paradox of choice Examines WHY having more choices would lead to fewer people buying it. Supports argument with evidence. Partially examines WHY having more choices would lead to fewer people buying it. Supports argument with weak or limited evidence. Partially examines WHY having more choices would lead to fewer people buying it. Does not support argument with evidence. __/6
Total: __/20

 

Assignment: Memory

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Study Guide

STEP 1: Imagine that one of your best friends is struggling with his classes. He aspires to graduate in exercise science and go on to earn a degree in occupational therapy, but he failed his first two chemistry exams. He’s feeling nervous about his performance and comes to you for advice. During your discussion, you learn that:

STEP 2: Based on this conversation, write an email to your friend (between 200-400 words), explaining to him why his studying habits are ineffective and what steps he might take to improve his learning. Include appropriate vocabulary from this module on memory, as well as things you’ve learned about consciousness and problem-solving from other modules.

Criteria Ratings Points
Presents a coherent argument of between 200-400 words Clearly writes a few paragraphs of between 200-400 words Writing is unclear, too short, or too long Writing is difficult to understand and/or too long or too short or does not present a coherent argument __/4
Characteristics of intelligence Provides specific recommendations for ways to address ALL seven of the problems listed, including references to problem-solving, consciousness, and memory. Includes appropriate vocabulary Provides answers and recommendations for between 4-6 of the problems listed OR makes seven underdeveloped recommendations Responds to three or fewer of the problems listed __/16
Total: __/20

Assignment: Learning

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Conditioning Project

STEP 1: Your assignment is to choose one of your OWN behaviors that you would like to modify, using the conditioning principles you learned about in the text. Consider bad habits you might be interested in changing, such as biting your nails, procrastinating, not exercising, etc. You can utilize principles of classical or operant conditioning, recruit others to help you, employ successive approximations and shaping and modify schedules of reinforcement in order to improve your life.

You must spend at least 10 solid days devoted to this project in order to see solid results.  Please get started right away.

STEP 2: Write a 2-3 page paper (500-800 words) about your project that explains your project, the type of conditioning you used, and the methods and procedures used to execute your project. You should explain the process of shaping the behavior and utilize any or all appropriate vocabulary. Finally, include a discussion of the results and an analysis of recommendations for improvement or future changes.

Criteria Ratings   Points
Project Chooses an appropriate project and spends at least 10 solid days trying to implement the behavior plan. Correctly identifies which type of conditioning is utilized Not the best choice for project or does not devote at least 10 days to changing the behavior Poor choice of project or insufficient time devoted to changing a behavior ___/5
Paper Format Types a 2-3 page double-spaced paper (12 pt font) about the behavior project. Paper has few or no grammatical errors and is easy to read Paper is too short, too long, or contains several grammatical errors Paper is too long or too short, contains many grammatical errors, or is difficult to read ___/5
Methods Explains the process in which the behavior was shaped and/or changed (how/why the project was chosen, what procedures were used, what schedule of reinforcement was used, etc.) Partially explains the process in which the behavior was shaped and/or changed (how/why the project was chosen, what procedures were used, what schedule of reinforcement was used, etc.) Incompletely explains the process in which the behavior was shaped and/or changed (how/why the project was chosen, what procedures were used, what schedule of reinforcement was used, etc.) ___/10
Academic Vocabulary Carefully identifies appropriate vocabulary (for example, if a classical conditioning project, identifies the N, UCR, UCR, CS, and CR, or if operant, identifies generalization, discriminations spontaneous recovery, fixed/variable ratio/interval schedule, etc) Partially identifies appropriate vocabulary (for example, if a classical conditioning project, identifies the N, UCR, UCR, CS, and CR, or if operant, identifies generalization, discriminations spontaneous recovery, fixed/variable ratio/interval schedule, etc) Does not or incompletely identifies appropriate vocabulary (for example, if a classical conditioning project, identifies the N, UCR, UCR, CS, and CR, or if operant, identifies generalization, discriminations spontaneous recovery, fixed/variable ratio/interval schedule, etc) ___/10
Analysis of Results Examines the results of the experiment. Explains whether the conditioning was successful, what could or should be changed if it were to be done again Partial examination of results and conclusions Incomplete examination of results and conclusions ___/10
Total: ___/40

Assignment: Lifespan Development

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Developmental Toys Assignment

STEP 1: Either go to a toy store or find some toys online. Pick toys that would be appropriate for each of the following ages:

STEP 2: Describe the toy and its purpose.

STEP 3: Describe both Piaget’s and Erikson’s stages of development at this age and explain why the toys you chose are appropriate for that age group. Add supporting evidence from your text. Each explanation should be in a paragraph or two between 100-150 words.

Criteria Ratings Points
6 month toy Describes the toy, its purpose, and describes developmental theories (both Piaget’s and Erikson’s) that support the appropriateness of the toy for 6 month olds Partially describes the toy, its purpose, and describes developmental theories (both Piaget’s and Erikson’s) that support the appropriateness of the toy for 6 month olds Little or weak explanation of the toy, its purpose, and appropriate developmental theories __/7
4 year old toy Describes the toy, its purpose, and describes developmental theories (both Piaget’s and Erikson’s) that support the appropriateness of the toy for 4 year olds Partially describes the toy, its purpose, and describes developmental theories (both Piaget’s and Erikson’s) that support the appropriateness of the toy for 4 year olds Little or weak explanation of the toy, its purpose, and appropriate developmental theories __/7
8 year old toy Describes the toy, its purpose, and describes developmental theories (both Piaget’s and Erikson’s) that support the appropriateness of the toy for 8 year olds Partially describes the toy, its purpose, and describes developmental theories (both Piaget’s and Erikson’s) that support the appropriateness of the toy for 8 year olds Little or weak explanation of the toy, its purpose, and appropriate developmental theories __/6
Total: __/20

Assignment: Social Psychology

20

Designing a Study in Social Psychology

For this assignment, you will design your very own psychology experiment or study. You will be creating a research proposal, modeled after actual research proposals (like the one found here), although yours will not need to be as long. Your finished product should be between 4-6 pages in 12 pt. font.

STEP 1: Pick a topic. Consider a topic within social psychology that interests you. Think of how you could design an experiment to test this theory. If you have a hard time thinking of an experiment, think of common proverbs or sayings and consider ways to test these proverbs. Possible proverbs to test include:

PART 1: Introduction/Abstract. Write a paragraph or two as an overview about your research proposal. Include the theory you are testing as well as your hypothesis.

PART 2: Literature Review/Background. Provide context for why you chose this topic and how your study will build off of other research. Find an academic study that has already been done related to your topic. Write a summary of what you learn from the article. You need to do this with at least TWO peer-reviewed journal articles. Peer-reviewed articles come from journals like those at the APA website, and not from simple Google searches or news websites. Most journals require a paid subscription but you can typically access them through your school library free of charge. Proper APA citations should be included. This should be roughly 1-2 pages in length.

PART 3: Method. Consider all of the questions below as you write out this main section of your research proposal. This should be roughly 1-2 pages in length.

PART 4: Results/Conclusion/Discussion. Write a summary paragraph about how you could and would utilize the results of your experiment.

Criteria  Ratings    Points
Overall paper Topic is connected to psychology and the overall paper utilizes good grammar, is easy to read, and between 4-6 pages in 12 pt. font. Topic is okay and/or paper has a few errors. Possibly too long or too short. Poor choice of topic or paper is difficult to read/contains many typos __/4
 Introduction/Abstract Includes an excellent introduction/abstract that explains the study in general terms. Identifies hypothesis. Includes an introduction/abstract that explains the study in general terms. Identifies hypothesis. Insufficient or non-existent introduction and hypothesis  __/5
Literature Review Finds at least TWO scholarly articles related to the topic for the literature review. Review is concise, informative, and properly cited. Finds ONE scholarly article or literature review is not fully developed Does not include scholarly articles or provides insufficient details in the literature review __/10
 Methods Clearly explains who will participate in the study, how they will be selected, and how this will control against bias. Explains who will participate in the study, how they will be selected, and how this will control against bias. Does not explain who will participate in the study, how they will be selected, and/or how this will control against bias. __/10
 Results Includes a detailed conclusion that considers the value of the potential results, and how results could prove or disprove the hypothesis. Conclusion that considers the results but lacks detail about how results could prove or disprove the hypothesis Insufficient conclusion __/7
 Citations Includes a reference page with at least 2 correct APA citations Includes a reference page with less than two correct APA citations Does not include reference page or correct references  __/4
 Total: __/40

Assignment: Personality

21

Assessing Personality

STEP 1: Take at least two of the personality tests mentioned in this module (or other legitimate tests):

  1. Big Five personality test: http://www.outofservice.com/bigfive/
  2. Kiersey Temperament Sorter http://www.keirsey.com/sorter/register.aspx. This test is very similar to the Myers-Briggs Type Indicator.
  3. Another Myers-Briggs type test: http://www.humanmetrics.com/cgi-win/jtypes2.asp
  4. Cattell’s 16PF questionnaire: http://personality-testing.info/tests/16PF.php
  5. Basic version of the color personality test: http://www.colorcode.com/choose_personality_test/

STEP 2: Analyze your results. Discuss the results with at least one other person who knows you (preferably someone who knows you well) and decide if you believe the results accurately describe who you are. Write a short essay (150-250 words) describing the tests and analyzing both their validity and reliability.

Criteria Ratings Points
Takes 2 personality tests Takes and shares the results of at least two personality tests and analyzes the personal results Takes the tests but does not describe or analyze the results or takes only one test Does not take two personality tests or analyze the results __/10
Validity and Reliability Uses appropriate detail and vocabulary to analyze the validity and reliability of the tests Analyzes the validity and reliability of the tests Does not analyze the validity and reliability of the tests __/10
Total: __/20

Assignment: Personality—Blirtatiousness

22

Based on your reading of the Psychology in Real Life activity on Blirtatiousness, explain the following terms as they relate to the blirtatiousness questionnaire:

Give examples from the study as to how these types of validity were examined in the Blirt test.

Finally, think of another way, not mentioned in the reading, that experimenters could test the validity of the Blirt test. What type of validity would you be testing? What would you expect the results of your validity test to be? Explain.

Criteria Ratings Points
Validity definitions Correctly defines and explains the following terms, using evidence and examples from the reading:
  • convergent validity
  • discriminant validity
  • criterion validity
  • predictive validity
Defines terms from the readings but with incomplete evidence or support Partially or incorrectly defines the terms from the readings with no or incomplete evidence __/12
Testing validity Accurately describes a potential way to test the validity of the Blirt test, and explains expected results Incompletely describes another potential way to test the validity of the Blirt test and expected results Does not describe or incorrectly describes a potential way to test the validity of the Blirt test __/8
Total: __/20

Assignment: Motivation and Emotion

23

Theories of Emotion

STEP 1: Using a stimulus of your choosing (not one found in your text) demonstrate the James-Lange, Cannon-Bard, Schachter-Singer, and cognitive-mediational theories of emotion. Describe each in just a few sentences.

Criteria Ratings Points
James-Lange Theory Demonstrates an understanding of the James-Lange theory and provides an appropriate example Provides an example of the James-Lange Theory but it is not clearly explained Does not demonstrate understanding of the James-Lange Theory __/5
Cannon-Bard Theory Demonstrates an understanding of the Cannon-Bard Theory theory and provides an appropriate example Provides an example of the Cannon-Bard Theory but it is not clearly explained Does not demonstrate understanding of the Cannon-Bard Theory __/5
Schachter-Singer Two-Factor Theory Demonstrates an understanding of the Schachter-Singer theory and provides an appropriate example Provides an example of the Schachter-Singer Theory but it is not clearly explained Does not demonstrate understanding of the Schachter-Singer Theory __/5
Cognitive-mediational Theory Demonstrates an understanding of the Cognitive-mediational Theory theory and provides an appropriate example Provides an example of the Cognitive-mediational Theory but it is not clearly explained  Does not demonstrate understanding of the Cognitive-mediational Theory  __/5
Total: __/20

Assignment: Growth Mindsets and the Control Condition

24

For this assignment, we’ll take a deeper look at some of the experimentation used in Carol Dweck’s research about Growth Mindsets.

Background

A control condition is usually considered to be a baseline, or the reference point from which you view the other conditions. We use the baseline/control condition to view the impact of the other conditions. Remember that in the Dweck study, the control condition was the situation where students were given general praise (“Wow, you did well!”) but the experimenter did not explain this performance as being based on either ability or effort. The experimental conditions were those in which the student received praise tied specifically to either their ability or for effort.

Notice in Figure 1 below that the students praised for ability were about 20% MORE likely to choose easy problems than those in the control condition. This suggests that praise focused on ability increases the likelihood that that child will select a practice set that is well within his or her existing ability.

Bar graph showing the likelihood of students choosing easy problems when they were praised for a) ability b) nothing in particular c) effort. Of those praised for ability, nearly 70% chose easy problems, while 50% of those in the control group chose easy problems, meaning that 20% more chose easy problems if they were praised for ability.
Figure 1. Notice the increased likelihood for students to choose easy problems if they were praised for their abilities, as compared with the control group.

Now look at the next figure (below), again using the control condition as your starting point. Praise for effort has had the opposite effect than praise for ability. Now the students are more than 40% less likely to choose easy problems—or, in other words, more than 40% more likely to choose challenging problems, even if they may fail at a lot of those problems.

Bar graph showing how the precent of students who chose easy problems who were praised for effort was only 10%, as compared with the control group of 50%.

Using a control condition properly doesn’t necessarily change your interpretation of the results, but it can give you a richer, more interesting view of the results. From this data so far, we can conclude that:

Example

Now imagine that the results had produced the pattern shown in the graph below. (These are not the correct results, but see if you can apply what you just learned about control conditions when interpreting the graph.)

Look at it closely, then let’s interpret the results. What does the bar graph tell us?

  1. The likelihood of choosing easy problems goes down as you go from praise for ability to praise for effort. This means that the praise-for-ability group is more likely to choose easy problems when compared with the effort group.
  2. The likelihood of choosing difficult problems goes up as you go from praise for ability to praise for effort. This means that the praise-for-effort group is less likely to choose easy problems.
  3. Praise for ability and praise for effort both results in choosing easier problems. This means that, based on the baseline/control, both ability-praise and effort-praise lead to greater preference for easy problems. True, the amount of increase differs between groups, but results like those above would suggest that any additional praise leads to learning strategies that preserve success at the cost of an opportunity to stretch and improve.

Assignment

For this assignment, you’ll interpret two hypothetical results, shown as bar graphs, from Dweck’s experiment about types of praise.

Part 1: Analyze the graph below. If 80% of the control group, given generic praise, chose easy questions, then what inferences can we make about praise given for ability and praise given for effort?

Part 2: Analyze the graph below. If 60% of those praised for ability chose easy problems, but 40% of those praised for effort and those given general praise chose easy problems, what inferences can we make about praise?

Bar graph showing the percentage of students who chose easy problems when praised for ability, praised for effort, or in the control group. 60% of those praised for ability chose easy problems, and 40% of those in the control group as well as 40% of those in the effort group chose easy problems.

Part 3: Write a summary paragraph describing the importance of the control group in interpreting results to psychological experiments. Why was the control group essential to the conclusion reached in Dweck’s research about mindset?

Criteria Ratings Points
Graph Analysis 1 Accurately describes the data shown in the first bar graph and correctly draws conclusions about the data based on the relationship of the control group to the ability and effort groups Partially draws conclusions about the data based on the relationship of the control group to the ability and effort groups Inaccurately draws conclusions about the relationship of the control group to the ability and effort groups __/6
Graph Analysis 2 Accurately describes the data shown in the second bar graph and correctly draws conclusions about the data based on the relationship of the control group to the ability and effort groups Partially draws conclusions about the data based on the relationship of the control group to the ability and effort groups Inaccurately draws conclusions about the relationship of the control group to the ability and effort groups __/6
Summary Writes a paragraph accurately emphasizing the importance of the control group; explains the necessity of the control group in Dweck’s research. Partially explains the importance of the control group and its importance to Dweck’s research; may not provide enough support or evidence from the research in response. Inaccurately or incompletely explains the importance of the control group. __/8
Total: __/20

Assignment: Industrial-Organizational Psychology

25

KSAs Assignment

In this assignment, you will write an essay of between 400-600 words about a profession you might enter.

Step 1: Consider what kind of job you would like to have when you “grow up,” then do a search on O*Net for at least three jobs that fit the designation of something you would be interested in doing. Read about the jobs paying close attention to the KSAs, then pick one to focus on for this assignment.

STEP 2: In your own words, write a summary about what KSAs are needed for your preferred future profession. Were there any KSAs that were surprising, or were others missing? What else did you learn about the job at this website?

STEP 3: Imagine you were going to hire someone to work in the profession you selected. Based on what you learned in this module about selecting employees, what would you recommend as an appropriate interview? How would you assess for the KSAs? Be sure to also consider how you might avoid bias during the interview process.

Criteria Ratings Points
Content Writes a detailed summary (200-300 words) explaining the KSAs needed for a particular profession as well as thing learned through the O*Net website Includes summary and explanation of KSAs and other facts learned from O*Net Includes a partial or incomplete summary and explanation of KSAs and other facts learned from O*Net __/10
Research and citations Explains (in between 200-300 words) an appropriate interview that would assess for the KSAs in the chosen profession. Also considers steps to avoid bias in the interview. Explains an interview for a profession that would assess for the KSAs and/or considers steps to avoid bias. Does not effectively explains an interview for a profession that would assess for the KSAs and/or considers steps to avoid bias. __/10
Total: __/20

Assignment: Psychological Disorders

26

Disorder At-a-Glance

STEP 1: Pick one of the disorders you read about in this module and learn more about it in order to make a “At-a-Glance” page with details about the disorder. Visit the National Institute of Mental Health and search for the disorder, read through the information, then scroll to the section on “Research and Statistics” or “Journal Articles or Reports” to find helpful links to outside information. Look elsewhere as well for details about the prevalence, signs, symptoms, details, and research related to the disorder. Keep track of all of your sources as you investigate.

STEP 2: In a format of your choosing (Microsoft Word, PowerPoint, Canva, Infogr.am, Photoshop, Google Doc, etc.), create a 1 page visual that includes the following information about the disorder:

STEP 3: Create a simple, yet visually interesting “At-a-Glance” page with information about the order. Although not required, we recommend adding a Creative Commons license to your completed work and uploading it to either Flickr or Wikimedia Commons so that other psychology instructors and students can use your work.

Criteria Ratings Points
Design Creates a simple, yet visually interesting design Has a simple design “At-a-Glance” is not visually interesting and/or poorly designed __/4
Content Includes detailed, yet concise, sections including the description, prevalence, and causes and risk factors of the illness Has sections on the description, prevalence, causes, and risk factors for an illness Incomplete or inaccurate sections on the description, prevalence, causes, and risk factors for an illness __/7
Research and citations Concisely and clearly explains at least two recent research articles (within the past 10 years), summarizes key research, and includes APA references Mentions at least two recent research articles (within the past 10 years), summarizes key research, and includes APA references Does not mentions at least two recent research articles (within the past 10 years), summarize the key research, or include appropriate APA references __/7
Total: __/20

Assignment: Therapy and Treatment

27

Treating Mental Illness

STEP 1: Review your previous discussion assignment about the fictional character who could be diagnosed with a psychological disorder.

STEP 2: Considering the diagnosis and disorder, describe THREE different treatment methods from your readings that could be used to treat the disorder. Give details about each method, then conclude with your recommendation for the best treatment or therapy method, and why. Essay should be between 200-400 words.

Criteria Ratings Points
Content Correctly describes 3 treatment methods Describes 2-3 treatment methods Partially describes 1-2 treatment methods __/12
Research and citations Effectively explains a recommendation for the best treatment method for the chosen disorder Explains a recommendation for the best treatment method for the chosen disorder Does not or only partially explains a recommendation for the best treatment method for the chosen disorder __/8
Total: __/20

Assignment: Stress, Lifestyle, and Health

28

Time and Stress Management

STEP 1: Choose ONE of the following activities to complete for this module. A description of how you will be graded is included with each explanation.

Psychological Foundations and Research Methods

III

Psychological Foundations

IV

Why It Matters: Psychological Foundations

29

An illustration shows the outlines of two human heads facing toward one another, with several photographs of people spread across the background.
(Image credit “background”: modification of work by Nattachai Noogure; credit “top left”: modification of work by U.S. Navy; credit “top middle-left”: modification of work by Peter Shanks; credit “top middle-right”: modification of work by “devinf”/Flickr; credit “top right”: modification of work by Alejandra Quintero Sinisterra; credit “bottom left”: modification of work by Gabriel Rocha; credit “bottom middle-left”: modification of work by Caleb Roenigk; credit “bottom middle-right”: modification of work by Staffan Scherz; credit “bottom right”: modification of work by Czech Provincial Reconstruction Team)

Clive Wearing is an accomplished musician who lost his ability to form new memories when he became sick at the age of 46. While he can remember how to play the piano perfectly, he cannot remember what he ate for breakfast just an hour ago (Sacks, 2007). James Wannerton experiences a taste sensation that is associated with the sound of words. His former girlfriend’s name tastes like rhubarb (Mundasad, 2013). John Nash is a brilliant mathematician and Nobel Prize winner. However, while he was a professor at MIT, he would tell people that the New York Times contained coded messages from extraterrestrial beings that were intended for him. He also began to hear voices and became suspicious of the people around him. Soon thereafter, Nash was diagnosed with schizophrenia and admitted to a state-run mental institution (O’Connor & Robertson, 2002). Nash was the subject of the 2001 movie A Beautiful Mind.

Why did these people have these experiences? How does the human brain work? And what is the connection between the brain’s internal processes and people’s external behaviors? This course will introduce you to various ways that the field of psychology has explored these questions. Psychology is the scientific study of behavior and mental processes—in this course, we will examine the connection between thoughts and actions and better understand how and why people think and behave.

This module will introduce you to what psychology is and what psychologists do. You’ll learn the basic history of the discipline and about the major domains and subdivisions that exist within modern psychology. Lastly, you’ll consider what it means to study psychology and what career options are available for those who do.

 

Module References

American Board of Forensic Psychology. (2014). Brochure. Retrieved from http://www.abfp.com/brochure.asp

American Psychological Association. (2014). Retrieved from www.apa.org

American Psychological Association. (2014). Graduate training and career possibilities in exercise and sport psychology. Retrieved from http://www.apadivisions.org/division-47/about/resources/training.aspx?item=1

American Psychological Association. (2011). Psychology as a career. Retrieved from http://www.apa.org/education/undergrad/psych-career.aspx

Ashliman, D. L. (2001). Cupid and Psyche. In Folktexts: A library of folktales, folklore, fairy tales, and mythology. Retrieved from http://www.pitt.edu/~dash/cupid.html

Betancourt, H., & López, S. R. (1993). The study of culture, ethnicity, and race in American psychology. American Psychologist, 48, 629–637.

Black, S. R., Spence, S. A., & Omari, S. R. (2004). Contributions of African Americans to the field of psychology. Journal of Black Studies, 35, 40–64.

Bulfinch, T. (1855). The age of fable: Or, stories of gods and heroes. Boston, MA: Chase, Nichols and Hill.

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Introduction to The History of Psychology

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What you’ll learn to do: describe the evolution of psychology and the major pioneers in the field

Painting of Plato and Aristotle.
Figure 1. Plato, Aristotle, and other ancient Greek philosophers examined a wide range of topics relating to what we now consider psychology.

Many cultures throughout history have speculated on the nature of the mind, heart, soul, spirit, and brain. Philosophical interest in behavior and the mind dates back to the ancient civilizations of Egypt, Greece, China, and India, but psychology as a discipline didn’t develop until the mid-1800s, when it evolved from the study of philosophy and began in German and American labs. This section will teach you more about the major founding psychologists and their contributions to the development of psychology.

Learning Objectives

  • Define psychology
  • Define structuralism and functionalism and the contributions of Wundt and James in the development of psychology
  • Describe Freud’s influence on psychology and his major theoretical contributions
  • Describe the basic tenets of Gestalt psychology
  • Define behaviorism and the contributions of Pavlov, Watson, and Skinner to psychology
  • Explain the basic tenets of humanism and Maslow’s contribution to psychology
  • Describe the basics of cognitive psychology and how the cognitive revolution shifted psychology’s focus back to the mind
  • Summarize the history of psychology, focusing on the major schools of thought

What is Psychology?

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Learning Objectives

  • Define Psychology

In Greek mythology, Psyche was a mortal woman whose beauty was so great that it rivaled that of the goddess Aphrodite. Aphrodite became so jealous of Psyche that she sent her son, Eros, to make Psyche fall in love with the ugliest man in the world. However, Eros accidentally pricked himself with the tip of his arrow and fell madly in love with Psyche himself. He took Psyche to his palace and showered her with gifts, yet she could never see his face. While visiting Psyche, her sisters roused suspicion in Psyche about her mysterious lover, and eventually, Psyche betrayed Eros’ wishes to remain unseen to her. Because of this betrayal, Eros abandoned Psyche. When Psyche appealed to Aphrodite to reunite her with Eros, Aphrodite gave her a series of impossible tasks to complete. Psyche managed to complete all of these trials; ultimately, her perseverance paid off as she was reunited with Eros and was ultimately transformed into a goddess herself (Ashliman, 2001; Greek Myths & Greek Mythology, 2014).

sculpture of a winged man embracing a woman
Figure 1. Antonio Canova’s sculpture depicts Eros and Psyche.

Psyche comes to represent the human soul’s triumph over the misfortunes of life in the pursuit of true happiness (Bulfinch, 1855); in fact, the Greek word psyche means soul, and it is often represented as a butterfly. The word psychology was coined at a time when the concepts of soul and mind were not as clearly distinguished (Green, 2001). The root -ology denotes scientific study of, and psychology refers to the scientific study of the mind. Since science studies only observable phenomena and the mind is not directly observable, we expand this definition to the scientific study of mental processes and behavior.

The scientific study of any aspect of the world uses the scientific method to acquire knowledge. To apply the scientific method, a researcher with a question about how or why something happens will propose a tentative explanation, called a hypothesis, to explain the phenomenon. A hypothesis is not just any explanation; it should fit into the context of a scientific theory. A scientific theory is a broad explanation or group of explanations for some aspect of the natural world that is consistently supported by evidence over time. A theory is the best understanding that we have of that part of the natural world. Armed with the hypothesis, the researcher then makes observations or, better still, carries out an experiment to test the validity of the hypothesis. That test and its results are then published so that others can check the results or build on them. It is necessary that any explanation in science be testable, which means that the phenomenon must be perceivable and measurable. For example, that a bird sings because it is happy is not a testable hypothesis, since we have no way to measure the happiness of a bird. We must ask a different question, perhaps about the brain state of the bird, since this can be measured. In general, science deals only with matter and energy, that is, those things that can be measured, and it cannot arrive at knowledge about values and morality. This is one reason why our scientific understanding of the mind is so limited, since thoughts, at least as we experience them, are neither matter nor energy. The scientific method is also a form of empiricism. An empirical method for acquiring knowledge is one based on observation, including experimentation, rather than a method based only on forms of logical argument or previous authorities.

It was not until the late 1800s that psychology became accepted as its own academic discipline. Before this time, the workings of the mind were considered under the auspices of philosophy. Given that any behavior is, at its roots, biological, some areas of psychology take on aspects of a natural science like biology. No biological organism exists in isolation, and our behavior is influenced by our interactions with others. Therefore, psychology is also a social science.

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Early Psychology—Structuralism and Functionalism

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Learning Objectives

  • Define structuralism and functionalism and the contributions of Wundt and James to the development of psychology

Psychology is a relatively young science with its experimental roots in the 19th century, compared, for example, to human physiology, which dates much earlier. As mentioned, anyone interested in exploring issues related to the mind generally did so in a philosophical context prior to the 19th century. Two men, working in the 19th century, are generally credited as being the founders of psychology as a science and academic discipline that was distinct from philosophy. Their names were Wilhelm Wundt and William James.

Wundt and Structuralism

Wilhelm Wundt (1832–1920) was a German scientist who was the first person to be referred to as a psychologist. His famous book entitled Principles of Physiological Psychology was published in 1873. Wundt viewed psychology as a scientific study of conscious experience, and he believed that the goal of psychology was to identify components of consciousness and how those components combined to result in our conscious experience. Wundt used introspection (he called it “internal perception”), a process by which someone examines their own conscious experience as objectively as possible, making the human mind like any other aspect of nature that a scientist observed.

Wundt’s version of introspection used only very specific experimental conditions in which an external stimulus was designed to produce a scientifically observable (repeatable) experience of the mind (Danziger, 1980). The first stringent requirement was the use of “trained” or practiced observers, who could immediately observe and report a reaction. The second requirement was the use of repeatable stimuli that always produced the same experience in the subject and allowed the subject to expect and thus be fully attentive to the inner reaction. These experimental requirements were put in place to eliminate “interpretation” in the reporting of internal experiences and to counter the argument that there is no way to know that an individual is observing their mind or consciousness accurately, since it cannot be seen by any other person.

This attempt to understand the structure or characteristics of the mind was known as structuralism. Wundt established his psychology laboratory at the University at Leipzig in 1879. In this laboratory, Wundt and his students conducted experiments on, for example, reaction times. A subject, sometimes in a room isolated from the scientist, would receive a stimulus such as a light, image, or sound. The subject’s reaction to the stimulus would be to push a button, and an apparatus would record the time to reaction. Wundt could measure reaction time to one-thousandth of a second (Nicolas & Ferrand, 1999).

Photograph A shows Wilhelm Wundt. Photograph B shows Wundt and five other people gathered around a desk with equipment on top of it.
Figure 1. (a) Wilhelm Wundt is credited as one of the founders of psychology. He created the first laboratory for psychological research. (b) This photo shows him seated and surrounded by fellow researchers and equipment in his laboratory in Germany.

However, despite his efforts to train individuals in the process of introspection, this process remained highly subjective, and there was very little agreement between individuals. As a result, structuralism fell out of favor with the passing of Wundt’s student, Edward Titchener, in 1927 (Gordon, 1995).

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Watch It

Watch this video to learn more about the early history of psychology.

Thumbnail for the embedded element "Psychology 101 - Wundt & James: Structuralism & Functionalism - Vook"

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A drawing depicts William James.
Figure 2. William James, shown here in a self-portrait, was the first American psychologist.

James and Functionalism

William James (1842–1910) was the first American psychologist who espoused a different perspective on how psychology should operate. James was introduced to Darwin’s theory of evolution by natural selection and accepted it as an explanation of an organism’s characteristics. Key to that theory is the idea that natural selection leads to organisms that are adapted to their environment, including their behavior. Adaptation means that a trait of an organism has a function for the survival and reproduction of the individual, because it has been naturally selected. As James saw it, psychology’s purpose was to study the function of behavior in the world, and as such, his perspective was known as functionalism.

Functionalism focused on how mental activities helped an organism fit into its environment. Functionalism has a second, more subtle meaning in that functionalists were more interested in the operation of the whole mind rather than of its individual parts, which were the focus of structuralism. Like Wundt, James believed that introspection could serve as one means by which someone might study mental activities, but James also relied on more objective measures, including the use of various recording devices, and examinations of concrete products of mental activities and of anatomy and physiology (Gordon, 1995).

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Adapted from Early Schools of Psychology from the Open Learning Initiative’s Introduction to Psychology. CC-BY-NC-SA. 
The Early Schools of Psychology (No Longer Active)
School of Psychology Description Historically Important People
Structuralism Focused on understanding the conscious experience through introspection Wilhelm Wundt
Functionalism Emphasized how mental activities helped an organism adapt to its environment William James

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The History of Psychology—Psychoanalytic Theory and Gestalt Psychology

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Learning Objectives

  • Describe Freud’s influence on psychology and his major theoretical contributions
  • Describe the basic tenets of Gestalt psychology
Photograph A shows Sigmund Freud. Image B shows the title page of his book, A General Introduction to Psychoanalysis.
Figure 1. (a) Sigmund Freud was a highly influential figure in the history of psychology. (b) One of his many books, A General Introduction to Psychoanalysis, shared his ideas about psychoanalytical therapy; it was published in 1922.
Perhaps one of the most influential and well-known figures in psychology’s history was Sigmund Freud. Freud (1856–1939) was an Austrian neurologist who was fascinated by patients suffering from “hysteria” and neurosis. Hysteria was an ancient diagnosis for disorders, primarily of women with a wide variety of symptoms, including physical symptoms and emotional disturbances, none of which had an apparent physical cause. Freud theorized that many of his patients’ problems arose from the unconscious mind. In Freud’s view, the unconscious mind was a repository of feelings and urges of which we have no awareness. Gaining access to the unconscious, then, was crucial to the successful resolution of the patient’s problems. According to Freud, the unconscious mind could be accessed through dream analysis, by examinations of the first words that came to people’s minds, and through seemingly innocent slips of the tongue. Psychoanalytic theory focuses on the role of a person’s unconscious, as well as early childhood experiences, and this particular perspective dominated clinical psychology for several decades (Thorne & Henley, 2005). Psychoanalytical theory is often used interchangeably with psychodynamic theory, but psychodynamic theory generally applies to a broader field of study based on Freud’s theories as well as those of his followers.
Image of iceberg, with most of the ice below the surface of the water.
Figure 2. Freud’s theory of the unconscious. Freud believed that we are only aware of a small amount of our mind’s activity, and that most of it remains hidden from us in our unconscious. The information in our unconscious affects our behavior, although we are unaware of it.

Id, Ego, and Superego

Freud’s structural model of personality divides the personality into three parts—the id, the ego, and the superego. The id is the unconscious part that is the cauldron of raw drives, such as for sex or aggression. The ego, which has conscious and unconscious elements, is the rational and reasonable part of personality. Its role is to maintain contact with the outside world to keep the individual in touch with society, and to do this it mediates between the conflicting tendencies of the id and the superego. The superego is a person’s conscience, which develops early in life and is learned from parents, teachers, and others. Like the ego, the superego has conscious and unconscious elements. When all three parts of the personality are in dynamic equilibrium, the individual is thought to be mentally healthy. However, if the ego is unable to mediate between the id and the superego, an imbalance is believed to occur in the form of psychological distress.

Psychosexual Theory of Development

Freud’s theories also placed a great deal of emphasis on sexual development. Freud believed that each of us must pass through a series of stages during childhood, and that if we lack proper nurturing during a particular stage, we may become stuck or fixated in that stage. Freud’s psychosexual model of development includes five stages: oral, anal, phallic, latency, and genital. According to Freud, children’s pleasure-seeking urges are focused on a different area of the body, called an erogenous zone, at each of these five stages. Psychologists today dispute that Freud’s psychosexual stages provide a legitimate explanation for how personality develops, but what we can take away from Freud’s theory is that personality is shaped, in some part, by experiences we have in childhood.

Freud’s ideas were influential, and you will learn more about them when you study lifespan development, personality, and therapy. For instance, many therapists believe strongly in the unconscious and the impact of early childhood experiences on the rest of a person’s life. The method of psychoanalysis, which involves the patient talking about their experiences and selves, while not invented by Freud, was certainly popularized by him and is still used today. Many of Freud’s other ideas, however, are controversial.

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Wertheimer, Koffka, Köhler and Gestalt Psychology

An ambiguous drawing looks like a duck facing to the left but also looks like a rabbit facing to the right.
Figure 3. When you look at this image, you may see a duck or a rabbit. The sensory information remains the same, but your perception can vary dramatically.
Max Wertheimer (1880–1943), Kurt Koffka (1886–1941), and Wolfgang Köhler (1887–1967) were three German psychologists who immigrated to the United States in the early 20th century to escape Nazi Germany. These men are credited with introducing psychologists in the United States to various Gestalt principles. The word Gestalt roughly translates to “whole;” a major emphasis of Gestalt psychology deals with the fact that although a sensory experience can be broken down into individual parts, how those parts relate to each other as a whole is often what the individual responds to in perception. For example, a song may be made up of individual notes played by different instruments, but the real nature of the song is perceived in the combinations of these notes as they form the melody, rhythm, and harmony. In many ways, this particular perspective would have directly contradicted Wundt’s ideas of structuralism (Thorne & Henley, 2005).
Gestalt image of showing a triangle with gaps in the middle of each side. On the exterior of the triangle, three circles leave out a small piece, making it appear as though there is a second triangle superimposed on the first, although it is really just the negative space.
Figure 4. The “invisible” triangle you see here is an example of gestalt perception.

Unfortunately, in moving to the United States, these men were forced to abandon much of their work and were unable to continue to conduct research on a large scale. These factors along with the rise of behaviorism (described next) in the United States prevented principles of Gestalt psychology from being as influential in the United States as they had been in their native Germany (Thorne & Henley, 2005). Despite these issues, several Gestalt principles are still very influential today. Considering the human individual as a whole rather than as a sum of individually measured parts became an important foundation in humanistic theory late in the century. The ideas of Gestalt have continued to influence research on sensation and perception.

Structuralism, Freud, and the Gestalt psychologists were all concerned in one way or another with describing and understanding inner experience. But other researchers had concerns that inner experience could be a legitimate subject of scientific inquiry and chose instead to exclusively study behavior, the objectively observable outcome of mental processes.

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Think It Over

Freud is probably one of the most well-known historical figures in psychology. Where have you encountered references to Freud or his ideas about the role that the unconscious mind plays in determining conscious behavior?

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The History of Psychology—Behaviorism and Humanism

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Learning Objectives

  • Define behaviorism and the contributions of Pavlov, Watson, and Skinner to psychology
  • Explain the basic tenets of humanism and Maslow’s contribution to psychology

Behavioral Psychology

Early work in the field of behavior was conducted by the Russian physiologist Ivan Pavlov (1849–1936). Pavlov studied a form of learning behavior called a conditioned reflex, in which an animal or human produced a reflex (unconscious) response to a stimulus and, over time, was conditioned to produce the response to a different stimulus that the experimenter associated with the original stimulus. The reflex Pavlov worked with was salivation in response to the presence of food. The salivation reflex could be elicited using a second stimulus, such as a specific sound, that was presented in association with the initial food stimulus several times. Once the response to the second stimulus was “learned,” the food stimulus could be omitted. Pavlov’s “classical conditioning” is only one form of learning behavior studied by behaviorists.

A photograph shows John B. Watson.
Figure 1. John B. Watson is known as the father of behaviorism within psychology.

John B. Watson (1878–1958) was an influential American psychologist whose most famous work occurred during the early 20th century at Johns Hopkins University. While Wundt and James were concerned with understanding conscious experience, Watson thought that the study of consciousness was flawed. Because he believed that objective analysis of the mind was impossible, Watson preferred to focus directly on observable behavior and try to bring that behavior under control. Watson was a major proponent of shifting the focus of psychology from the mind to behavior, and this approach of observing and controlling behavior came to be known as behaviorism. A major object of study by behaviorists was learned behavior and its interaction with inborn qualities of the organism. Behaviorism commonly used animals in experiments under the assumption that what was learned using animal models could, to some degree, be applied to human behavior. Indeed, Tolman (1938) stated, “I believe that everything important in psychology (except … such matters as involve society and words) can be investigated in essence through the continued experimental and theoretical analysis of the determiners of rat behavior at a choice-point in a maze.”

Behaviorism dominated experimental psychology for several decades, and its influence can still be felt today (Thorne & Henley, 2005). Behaviorism is largely responsible for establishing psychology as a scientific discipline through its objective methods and especially experimentation. In addition, it is used in behavioral and cognitive-behavioral therapy. Behavior modification is commonly used in classroom settings. Behaviorism has also led to research on environmental influences on human behavior.

B. F. Skinner (1904–1990) was an American psychologist. Like Watson, Skinner was a behaviorist, and he concentrated on how behavior was affected by its consequences. Therefore, Skinner spoke of reinforcement and punishment as major factors in driving behavior. As a part of his research, Skinner developed a chamber that allowed the careful study of the principles of modifying behavior through reinforcement and punishment. This device, known as an operant conditioning chamber (or more familiarly, a Skinner box), has remained a crucial resource for researchers studying behavior (Thorne & Henley, 2005).

Photograph A shows B.F. Skinner. Illustration B shows a rat in a Skinner box: a chamber with a speaker, lights, a lever, and a food dispenser.
Figure 2. (a) B. F. Skinner is famous for his research on operant conditioning. (b) Modified versions of the operant conditioning chamber, or Skinner box, are still widely used in research settings today. (credit a: modification of work by “Silly rabbit”/Wikimedia Commons)

The Skinner box is a chamber that isolates the subject from the external environment and has a behavior indicator such as a lever or a button. When the animal pushes the button or lever, the box is able to deliver a positive reinforcement of the behavior (such as food) or a punishment (such as a noise) or a token conditioner (such as a light) that is correlated with either the positive reinforcement or punishment.

Skinner’s focus on positive and negative reinforcement of learned behaviors had a lasting influence in psychology that has waned somewhat since the growth of research in cognitive psychology. Despite this, conditioned learning is still used in human behavioral modification. Skinner’s two widely read and controversial popular science books about the value of operant conditioning for creating happier lives remain as thought-provoking arguments for his approach (Greengrass, 2004).

During the early 20th century, American psychology was dominated by behaviorism and psychoanalysis. However, some psychologists were uncomfortable with what they viewed as limited perspectives being so influential to the field. They objected to the pessimism and determinism (all actions driven by the unconscious) of Freud. They also disliked the reductionism, or simplifying nature, of behaviorism. Behaviorism is also deterministic at its core, because it sees human behavior as entirely determined by a combination of genetics and environment. Some psychologists began to form their own ideas that emphasized personal control, intentionality, and a true predisposition for “good” as important for our self-concept and our behavior. Thus, humanism emerged.

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Maslow, Rogers, and Humanism

Humanism is a perspective within psychology that emphasizes the potential for good that is innate to all humans. Two of the most well-known proponents of humanistic psychology are Abraham Maslow and Carl Rogers (O’Hara, n.d.). Abraham Maslow (1908–1970) was an American psychologist who is best known for proposing a hierarchy of human needs in motivating behavior. Although this concept will be discussed in more detail in a later section, a brief overview will be provided here.

Maslow's Hierarchy of Needs. At the bottom of the pyramid are physiological needs (food, water, shelter, warmth), then security needs (safety, employment, assets), social needs (family, friendship, intimacy, belonging), then esteem (self-worth, accomplishment, confidence), and lastly, self-actualization (inner fulfillment).
Figure 3. Maslow’s hierarchy of needs emphasizes that basic needs for food and safety need to be met before higher level needs can serve as motivators.

Maslow asserted that so long as basic needs necessary for survival were met (e.g., food, water, shelter), higher-level needs (e.g., social needs) would begin to motivate behavior. According to Maslow, the highest-level needs relate to self-actualization, a process by which we achieve our full potential. Obviously, the focus on the positive aspects of human nature that are characteristic of the humanistic perspective is evident (Thorne & Henley, 2005).

Humanistic psychologists rejected, on principle, the research approach based on reductionist experimentation in the tradition of the physical and biological sciences, because it missed the “whole” human being. Beginning with Maslow and Rogers, there was an insistence on a humanistic research program. This program has been largely qualitative (not measurement-based), but there exist a number of quantitative research strains within humanistic psychology, including research on happiness, self-concept, meditation, and the outcomes of humanistic psychotherapy (Friedman, 2008).

Carl Rogers (1902–1987) was also an American psychologist who, like Maslow, emphasized the potential for good that exists within all people. Rogers used a therapeutic technique known as client-centered therapy in helping his clients deal with problematic issues that resulted in their seeking psychotherapy. Unlike a psychoanalytic approach in which the therapist plays an important role in interpreting what conscious behavior reveals about the unconscious mind, client-centered therapy involves the patient taking a lead role in the therapy session. Rogers believed that a therapist needed to display three features to maximize the effectiveness of this particular approach: unconditional positive regard, genuineness, and empathy. Unconditional positive regard refers to the fact that the therapist accepts their client for who they are, no matter what he or she might say. Provided these factors, Rogers believed that people were more than capable of dealing with and working through their own issues (Thorne & Henley, 2005).

Humanism has been influential to psychology as a whole. Both Maslow and Rogers are well-known names among students of psychology (you will read more about both men later in this text), and their ideas have influenced many scholars. Furthermore, Rogers’ client-centered approach to therapy is still commonly used in psychotherapeutic settings today (O’hara, n.d.).

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The History of Psychology—The Cognitive Revolution and Multicultural Psychology

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Learning Objectives

  • Describe the basics of cognitive psychology and how the cognitive revolution shifted psychology’s focus back to the mind
  • Summarize the history of psychology, focusing on the major schools of thought

Behaviorism and the Cognitive Revolution

Behaviorism’s emphasis on objectivity and focus on external behavior had pulled psychologists’ attention away from the mind for a prolonged period of time. The early work of the humanistic psychologists redirected attention to the individual human as a whole, and as a conscious and self-aware being. By the 1950s, new disciplinary perspectives in linguistics, neuroscience, and computer science were emerging, and these areas revived interest in the mind as a focus of scientific inquiry. This particular perspective has come to be known as the cognitive revolution (Miller, 2003). By 1967, Ulric Neisser published the first textbook entitled Cognitive Psychology, which served as a core text in cognitive psychology courses around the country (Thorne & Henley, 2005).

Although no one person is entirely responsible for starting the cognitive revolution, Noam Chomsky was very influential in the early days of this movement. Chomsky (1928–), an American linguist, was dissatisfied with the influence that behaviorism had had on psychology. He believed that psychology’s focus on behavior was short-sighted and that the field had to re-incorporate mental functioning into its purview if it were to offer any meaningful contributions to understanding behavior (Miller, 2003).

A photograph shows a mural on the side of a building. The mural includes Chomsky's face, along with some newspapers, televisions, and cleaning products. At the top of the mural, it reads “Noam Chomsky.” At the bottom of the mural, it reads “the most important intellectual alive.”
Figure 1. Noam Chomsky was very influential in beginning the cognitive revolution. In 2010, this mural honoring him was put up in Philadelphia, Pennsylvania. (credit: Robert Moran)

European psychology had never really been as influenced by behaviorism as had American psychology; and thus, the cognitive revolution helped reestablish lines of communication between European psychologists and their American counterparts. Furthermore, psychologists began to cooperate with scientists in other fields, like anthropology, linguistics, computer science, and neuroscience, among others. This interdisciplinary approach often was referred to as the cognitive sciences, and the influence and prominence of this particular perspective resonates in modern-day psychology (Miller, 2003).

Cognitive Psychology

Cognitive psychology is radically different from previous psychological approaches in that it is characterized by both of the following:

  1. It accepts the use of the scientific method and generally rejects introspection as a valid method of investigation, unlike phenomenological methods such as Freudian psychoanalysis.
  2. It explicitly acknowledges the existence of internal mental states (such as belief, desire, and motivation), unlike behaviorist psychology.

Cognitive theory contends that solutions to problems take the form of algorithms, heuristics, or insights. Major areas of research in cognitive psychology include perception, memory, categorization, knowledge representation, numerical cognition, language, and thinking.

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Multicultural Psychology

Culture has important impacts on individuals and social psychology, yet the effects of culture on psychology are under-studied. There is a risk that psychological theories and data derived from white, American settings could be assumed to apply to individuals and social groups from other cultures and this is unlikely to be true (Betancourt & López, 1993). One weakness in the field of cross-cultural psychology is that in looking for differences in psychological attributes across cultures, there remains a need to go beyond simple descriptive statistics (Betancourt & López, 1993). In this sense, it has remained a descriptive science, rather than one seeking to determine cause and effect. For example, a study of characteristics of individuals seeking treatment for a binge eating disorder in Hispanic American, African American, and Caucasian American individuals found significant differences between groups (Franko et al., 2012). The study concluded that results from studying any one of the groups could not be extended to the other groups, and yet potential causes of the differences were not measured.

This history of multicultural psychology in the United States is a long one. The role of African American psychologists in researching the cultural differences between African American individual and social psychology is but one example. In 1920, Cecil Sumner was the first African American to receive a PhD in psychology in the United States. Sumner established a psychology degree program at Howard University, leading to the education of a new generation of African American psychologists (Black, Spence, and Omari, 2004). Much of the work of early African American psychologists (and a general focus of much work in first half of the 20th century in psychology in the United States) was dedicated to testing and intelligence testing in particular (Black et al., 2004). That emphasis has continued, particularly because of the importance of testing in determining opportunities for children, but other areas of exploration in African-American psychology research include learning style, sense of community and belonging, and spiritualism (Black et al., 2004).

The American Psychological Association has several ethnically based organizations for professional psychologists that facilitate interactions among members. Since psychologists belonging to specific ethnic groups or cultures have the most interest in studying the psychology of their communities, these organizations provide an opportunity for the growth of research on the impact of culture on individual and social psychology.

Summary of the History of Psychology

Before the time of Wundt and James, questions about the mind were considered by philosophers. However, both Wundt and James helped create psychology as a distinct scientific discipline. Wundt was a structuralist, which meant he believed that our cognitive experience was best understood by breaking that experience into its component parts. He thought this was best accomplished by introspection.

William James was the first American psychologist, and he was a proponent of functionalism. This particular perspective focused on how mental activities served as adaptive responses to an organism’s environment. Like Wundt, James also relied on introspection; however, his research approach also incorporated more objective measures as well.

Sigmund Freud believed that understanding the unconscious mind was absolutely critical to understand conscious behavior. This was especially true for individuals that he saw who suffered from various hysterias and neuroses. Freud relied on dream analysis, slips of the tongue, and free association as means to access the unconscious. Psychoanalytic theory remained a dominant force in clinical psychology for several decades.

Gestalt psychology was very influential in Europe. Gestalt psychology takes a holistic view of an individual and his experiences. As the Nazis came to power in Germany, Wertheimer, Koffka, and Köhler immigrated to the United States. Although they left their laboratories and their research behind, they did introduce America to Gestalt ideas. Some of the principles of Gestalt psychology are still very influential in the study of sensation and perception.

One of the most influential schools of thought within psychology’s history was behaviorism. Behaviorism focused on making psychology an objective science by studying overt behavior and deemphasizing the importance of unobservable mental processes. John Watson is often considered the father of behaviorism, and B. F. Skinner’s contributions to our understanding of principles of operant conditioning cannot be underestimated.

As behaviorism and psychoanalytic theory took hold of so many aspects of psychology, some began to become dissatisfied with psychology’s picture of human nature. Thus, a humanistic movement within psychology began to take hold. Humanism focuses on the potential of all people for good. Both Maslow and Rogers were influential in shaping humanistic psychology.

During the 1950s, the landscape of psychology began to change. A science of behavior began to shift back to its roots of focus on mental processes. The emergence of neuroscience and computer science aided this transition. Ultimately, the cognitive revolution took hold, and people came to realize that cognition was crucial to a true appreciation and understanding of behavior.

Early Schools of Psychology: Still Active and Advanced Beyond Early Ideas
School of Psychology Description Earliest Period Historically Important People
Psychodynamic Psychology Focuses on the role of the unconscious and childhood experiences in affecting conscious behavior. Very late 19th to Early 20th Century Sigmund Freud, Erik Erikson
Behaviorism Focuses on observing and controlling behavior through what is observable. Puts an emphasis on learning and conditioning. Early 20th Century Ivan Pavlov, John B. Watson, B. F. Skinner
Humanistic Psychology Emphasizes the potential for good that is innate to all humans and rejects that psychology should focus on problems and disorders. 1950s Abraham Maslow, Carl Rogers
Cognitive Psychology Focuses not just on behavior, but on on mental processes and internal mental states. 1960sAlthough Piaget's research on cognition began in the 1920s, cognitive psychology did not become mainstream until the 1960s. Ulric Neisser, Noam Chomsky, Jean Piaget, Lev Vygotsky

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Introduction to Contemporary Fields in Psychology

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What you’ll learn to do: identify the various approaches, fields, and subfields of psychology along with their major concepts and important figures

black and white photo of a woman standing in front of a subway as it zips past her.

This section will provide an overview of the major domains of psychology today, as well as some additional sub-fields and content areas. This is not meant to be an exhaustive listing, but it will provide insight into the major areas of research and practice of modern-day psychologists. You’ll come to see that while psychology is defined as the study of the mind and behavior, there are many different types of psychologists who emphasize and apply psychological principles in various ways.

For example, imagine that a woman is diagnosed with depression. What is the cause of the depression? Is it her biology or chemical imbalances in her brain? Evolutionary predispositions? Perhaps it is caused by experiences in her past, or something else that triggered a downward spiral of emotions? Or maybe it is caused by social factors, or cultural expectations? All of these things could, in fact, play a role in her depression. In this section, you’ll see how psychologists analyze behavior from a variety of perspectives and better understand the breadth of psychology.

Learning Objectives

  • List and define the five major domains, or pillars, of contemporary psychology
  • Describe the basic interests and applications of biopsychology and evolutionary psychology
  • Describe the basic interests and applications of cognitive psychology
  • Describe the basic interests and applications of developmental psychology
  • Describe the basic interests and applications of social psychology and personality psychology
  • Describe the basic interests and applications of abnormal, clinical, and health psychology
  • Define industrial-organizational psychology, sport and exercise psychology, and forensic psychology

The Five Psychological Domains

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Learning Objectives

  • List and define the five major domains, or pillars, of contemporary psychology

Introduction to Contemporary Psychology

Contemporary psychology is a diverse field that is influenced by all of the historical perspectives described in the previous section of reading. Reflective of the discipline’s diversity is the diversity seen within the American Psychological Association (APA). The APA is a professional organization representing psychologists in the United States. The APA is the largest organization of psychologists in the world, and its mission is to advance and disseminate psychological knowledge for the betterment of people. There are 56 divisions within the APA, representing a wide variety of specialties that range from Societies for the Psychology of Religion and Spirituality to Exercise and Sport Psychology to Behavioral Neuroscience and Comparative Psychology. Reflecting the diversity of the field of psychology itself, members, affiliate members, and associate members span the spectrum from students to doctoral-level psychologists, and come from a variety of places including educational settings, criminal justice, hospitals, the armed forces, and industry (American Psychological Association, 2014).

Link to Learning

Please visit this APA divisions website to see a list of all the divisions and to learn more about them. Student resources are also available through the APA.

Psychologists agree that there is no one right way to study the way people think or behave. There are, however, various schools of thought that evolved throughout the development of psychology that continue to shape the way we investigate human behavior. For example, some psychologists might attribute a certain behavior to biological factors such as genetics while another psychologist might consider early childhood experiences to be a more likely explanation for the behavior. Many expert psychologists focus their entire careers on just one facet of psychology, such as developmental psychology or cognitive psychology, or even more specifically, newborn intelligence or language processing.

While the field of study is large and vast, this text aims to introduce you to the main topics with psychology. You’ll get exposure to the various branches and sub-fields within the discipline and come to understand how they are all interconnected and essential in understanding behavior and mental processes. The five main psychological pillars, or domains, as we will refer to them, are:

  1. Domain 1: Biological (includes neuroscience, consciousness, and sensation)
  2. Domain 2: Cognitive (includes the study of perception, cognition, memory, and intelligence)
  3. Domain 3: Development (includes learning and conditioning, lifespan development, and language)
  4. Domain 4: Social and Personality (includes the study of personality, emotion, motivation, gender, and culture)
  5. Domain 5: Mental and Physical Health (includes abnormal psychology, therapy, and health psychology)
Image of five pillars, showing the biological, cognitive, developmental, social and personality, and mental and physical health.
Figure 1. The five pillars, or domains, of psychology. Image adapted from Gurung, R. A., Hackathorn, J., Enns, C., Frantz, S., Cacioppo, J. T., Loop, T., & Freeman, J. E. (2016) article “Strengthening introductory psychology: A new model for teaching the introductory course” from American Psychologist.

These five domains cover the main viewpoints, or perspectives, of psychology. These perspectives emphasize certain assumptions about behavior and provide a framework for psychologists in conducting research and analyzing behavior. They include some you have already read about, including Freud’s psychodynamic perspective, behaviorism, humanism, and the cognitive approach. Other perspectives include the biological perspective, evolutionary, and socio-cultural perspectives.

Helpful Hints

A neat way to remember the major perspectives in psychology is to think about your hand and associate each finger with a prominent psychological approach:

  • Index Finger: Tap your finger to the temple of your head as if you were thinking about something. This is the cognitive perspective.
  • Middle Finger: If you stuck up your middle finger to flip someone off, that would be bad behavior in many cultures. This represents the behavioral perspective, which falls under the developmental domain.
  • Ring Finger: This is typically where you would wear a wedding band. For some people this is a healthy lifestyle choice, and for others this is a cause of stress. For some, the thought of marriage causes anxiety, which may lead to therapy. This represents the mental and physical health domain.
  • Pinky Finger: This little finger was born this way—short. You can thank your biology for that. This represents the biological perspective.
  • Palm of hand: In many cultures, giving a high-five is an acceptable greeting. This represents the social and personality domain.
  • Bonus: Thumb: your thumb can move around in psycho ways—it’s so versatile! This is the psychodynamic perspective, which is not its own pillar but represents a prominent historical perspective and school of thought in psychology, as explained earlier.

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The Biological Domain

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Learning Objectives

  • Describe the basic interests and applications of biopsychology and evolutionary psychology

Biopsychology—also known as biological psychology or psychobiology—is the application of the principles of biology to the study of mental processes and behavior. As the name suggests, biopsychology explores how our biology influences our behavior. While biological psychology is a broad field, many biological psychologists want to understand how the structure and function of the nervous system is related to behavior. The fields of behavioral neuroscience, cognitive neuroscience, and neuropsychology are all subfields of biological psychology.

The inside of a human brain
Figure 1. Different brain-imaging techniques provide scientists with insight into different aspects of how the human brain functions. 

The research interests of biological psychologists span a number of domains, including but not limited to, sensory and motor systems, sleep, drug use and abuse, ingestive behavior, reproductive behavior, neurodevelopment, plasticity of the nervous system, and biological correlates of psychological disorders. Given the broad areas of interest falling under the purview of biological psychology, it will probably come as no surprise that individuals from all sorts of backgrounds are involved in this research, including biologists, medical professionals, physiologists, and chemists. This interdisciplinary approach is often referred to as neuroscience, of which biological psychology is a component (Carlson, 2013).

Evolutionary Psychology

While biopsychology typically focuses on the immediate causes of behavior based in the physiology of a human or other animal, evolutionary psychology seeks to study the ultimate biological causes of behavior. Just as genetic traits have evolved and adapted over time, psychological traits can also evolve and be determined through natural selection. Evolutionary psychologists study the extent that a behavior is impacted by genetics. The study of behavior in the context of evolution has its origins with Charles Darwin, the co-discoverer of the theory of evolution by natural selection. Darwin was well aware that behaviors should be adaptive and wrote books titled, The Descent of Man (1871) and The Expression of the Emotions in Man and Animals (1872), to explore this field.

Image of five pillars, showing the biological, cognitive, developmental, social and personality, and mental and physical health.
Figure 2. The biological domain of psychology covers fields like neuroscience, evolutionary psychology, sensation, and consciousness.

Evolutionary psychology is based on the hypothesis that, just like hearts, lungs, livers, kidneys, and immune systems, cognition has functional structure that has a genetic basis, and therefore has evolved by natural selection. They seek to understand psychological mechanisms by understanding the survival and reproductive functions they might have served over the course of evolutionary history. These might include abilities to infer others’ emotions, discern kin from non-kin, identify and prefer healthier mates, cooperate with others and follow leaders. Consistent with the theory of natural selection, evolutionary psychology sees humans as often in conflict with others, including mates and relatives. For instance, a mother may wish to wean her offspring from breastfeeding earlier than does her infant, which frees up the mother to invest in additional offspring.

Evolutionary psychology, and specifically, the evolutionary psychology of humans, has enjoyed a resurgence in recent decades. To be subject to evolution by natural selection, a behavior must have a significant genetic cause. In general, we expect all human cultures to express a behavior if it is caused genetically, since the genetic differences among human groups are small. The approach taken by most evolutionary psychologists is to predict the outcome of a behavior in a particular situation based on evolutionary theory and then to make observations, or conduct experiments, to determine whether the results match the theory.

There are many areas of human behavior for which evolution can make predictions. Examples include memory, mate choice, relationships between kin, friendship and cooperation, parenting, social organization, and status (Confer et al., 2010).

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Evolutionary psychologists have had success in finding experimental correspondence between observations and expectations. In one example, in a study of mate preference differences between men and women that spanned 37 cultures, Buss (1989) found that women valued earning potential factors greater than men, and men valued potential reproductive factors (youth and attractiveness) greater than women in their prospective mates. In general, the predictions were in line with the predictions of evolution, although there were deviations in some cultures.

Sensation and Perception

Scientists interested in both physiological aspects of sensory systems as well as in the psychological experience of sensory information work within the area of sensation and perception. As such, sensation and perception research is also quite interdisciplinary. Imagine walking between buildings as you move from one class to another. You are inundated with sights, sounds, touch sensations, and smells. You also experience the temperature of the air around you and maintain your balance as you make your way. These are all factors of interest to someone working in the domain of sensation and perception.

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The Cognitive Domain

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Learning Objectives

  • Describe the basic interests and applications of cognitive psychology
Chimpanze with his hand to his mouth, looking thoughtful and pensive.
Figure 1. Cognitive psychology sometimes involves the use of animals to examine the ways they think and solve problems.

As mentioned in your previous reading, the cognitive revolution created an impetus for psychologists to focus their attention on better understanding the mind and mental processes that underlie behavior. Thus, cognitive psychology is the area of psychology that focuses on studying cognitions, or thoughts, and their relationship to our experiences and our actions. Like biological psychology, cognitive psychology is broad in its scope and often involves collaborations among people from a diverse range of disciplinary backgrounds. This has led some to coin the term cognitive science to describe the interdisciplinary nature of this area of research (Miller, 2003).

Cognitive psychologists have research interests that span a spectrum of topics, ranging from attention to problem solving to language to memory. The approaches used in studying these topics are equally diverse. The bulk of content coverage on cognitive psychology will be covered in the modules in this text on thinking, intelligence, and memory. But given its diversity, various concepts related to cognitive psychology will be covered in other sections such as lifespan development, social psychology, and therapy.

The five pillars of psychology: biological, cognitive, developmental, social and personality, and mental and physical health.
Figure 2. The cognitive domain of psychology covers content on perception, thinking, intelligence, and memory.

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The Developmental Domain

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Learning Objectives

  • Describe the basic interests and applications of developmental psychology
Image of five pillars, showing the biological, cognitive, developmental, social and personality, and mental and physical health.
Figure 1. The developmental domain of psychology includes topics on learning and conditioning as well as lifespan development.

Developmental psychology is the scientific study of development across a lifespan. Developmental psychologists are interested in processes related to physical maturation. However, their focus is not limited to the physical changes associated with aging, as they also focus on changes in cognitive skills, moral reasoning, social behavior, and other psychological attributes. Early developmental psychologists focused primarily on changes that occurred through reaching adulthood, providing enormous insight into the differences in physical, cognitive, and social capacities that exist between very young children and adults. For instance, research by Jean Piaget demonstrated that very young children do not demonstrate object permanence. Object permanence refers to the understanding that physical things continue to exist, even if they are hidden from us.

Jean Piaget in his older years, standing with his hands in his pockets in a black suit, tie, and vest. He's wearing glasses and a beret.
Figure 2. Piaget is best known for his stage theory of cognitive development.

If you were to show an adult a toy, and then hide it behind a curtain, the adult knows that the toy still exists. However, very young infants act as if a hidden object no longer exists. The age at which object permanence is achieved is somewhat controversial (Munakata, McClelland, Johnson, and Siegler, 1997).

While Piaget was focused on cognitive changes during infancy and childhood as we move to adulthood, there is an increasing interest in extending research into the changes that occur much later in life. This may be reflective of changing population demographics of developed nations as a whole. As more and more people live longer lives, the number of people of advanced age will continue to increase. Indeed, it is estimated that there were just over 40 million people aged 65 or older living in the United States in 2010. However, by 2020, this number is expected to increase to about 55 million. By the year 2050, it is estimated that nearly 90 million people in this country will be 65 or older (Department of Health and Human Services, n.d.).

Behavioral Psychology

Another critical field of study under the development domain is that of learning and behaviorism, which you read about already. The primary developments in learning and conditioning came from the work of Ivan Pavlov, John B. Watson, Edward Lee Thorndike, and B. F. Skinner. Contemporary behaviorists apply learning techniques in the form of behavior modification for a variety of mental problems. Learning is seen as behavior change molded by experience; it is accomplished largely through either classical or operant conditioning.

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The Social and Personality Psychology Domain

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Learning Objectives

  • Describe the basic interests and applications of social psychology and personality psychology

Social Psychology

Social psychology is the scientific study of how people’s thoughts, feelings, and behaviors are influenced by the actual, imagined, or implied presence of others. This domain of psychology is concerned with the way such feelings, thoughts, beliefs, intentions, and goals are constructed, and how these psychological factors, in turn, influence our interactions with others.

Image of five pillars, showing the biological, cognitive, developmental, social and personality, and mental and physical health.
Figure 1. Social and personality psychology includes the study of human groups and interaction, the development and analysis of personality, the experience and interpretation of emotion, and motivation.

Social psychology typically explains human behavior as a result of the interaction of mental states and immediate social situations. Social psychologists, therefore, examine the factors that lead us to behave in a given way in the presence of others, as well as the conditions under which certain behaviors, actions, and feelings occur. They focus on how people construe or interpret situations and how these interpretations influence their thoughts, feelings, and behaviors (Ross & Nisbett, 1991). Thus, social psychology studies individuals in a social context and how situational variables interact to influence behavior.

Some social psychologists study large-scale sociocultural forces within cultures and societies that affect the thoughts, feelings, and behaviors of individuals. These include forces such as attitudes, child-rearing practices, discrimination and prejudice, ethnic and racial identity, gender roles and norms, family and kinship structures, power dynamics, regional differences, religious beliefs and practices, rituals, and taboos. Several subfields within psychology seek to examine these sociocultural factors that influence human mental states and behavior; among these are social psychology, cultural psychology, cultural-historical psychology, and cross-cultural psychology.

An advertisement reads: “Public Announcement. We will pay you $4.00 for one hour of your time. Persons Needed for a Study of Memory. We will pay five hundred New Haven men to help us complete a scientific study of memory and learning. The study is being done at Yale University. Each person who participates will be paid $4.00 (plus 50 cents carfare) for approximately 1 hour’s time. We need you for only one hour: there are no further obligations. You may choose the time you would like to come (evenings, weekdays, or weekends). No special training, education, or experience is needed. We want: factory workers, city employees, laborers, barbers, businessmen, clerks, professional people, telephone workers, construction workers, salespeople, white-collar workers, and others. All persons must be between the ages of 20 and 50. High school and college students cannot be used. If you meet these qualifications, fill out the coupon below and mail it now to Professor Stanley Milgram, Department of Psychology, Yale University, New Haven. You will be notified later of the specific time and place of the study. We reserve the right to decline any application. You will be paid $4.00 (plus 50 cents carfare) as soon as you arrive at the laboratory.” There is a dotted line and the below section reads: “TO: PROF. STANLEY MILGRAM, DEPARTMENT OF PSYCHOLOGY, YALE UNIVERSITY, NEW HAVEN, CONN. I want to take part in this study of memory and learning. I am between the ages of 20 and 50. I will be paid $4.00 (plus 50 cents carfare) if I participate.” Below this is a section to be filled out by the applicant. The fields are NAME (Please Print), ADDRESS, TELEPHONE NO. Best time to call you, AGE, OCCUPATION, SEX, CAN YOU COME: WEEKDAYS, EVENINGS, WEEKENDS."
Figure 2. Stanley Milgram’s research demonstrated just how far people will go in obeying orders from an authority figure. This advertisement was used to recruit subjects for his research.

There are many interesting examples of social psychological research, and you will read about many of these later in this course. Until then, you will be introduced to one of the most controversial psychological studies ever conducted. Stanley Milgram was an American social psychologist who is most famous for research that he conducted on obedience. After the Holocaust, in 1961, a Nazi war criminal, Adolf Eichmann, who was accused of committing mass atrocities, was put on trial. Many people wondered how German soldiers were capable of torturing prisoners in concentration camps, and they were unsatisfied with the excuses given by soldiers that they were simply following orders. At the time, most psychologists agreed that few people would be willing to inflict such extraordinary pain and suffering, simply because they were obeying orders. Milgram decided to conduct research to determine whether or not this was true.

As you will read later in the text, Milgram found that nearly two-thirds of his participants were willing to deliver what they believed to be lethal shocks to another person, simply because they were instructed to do so by an authority figure (in this case, a man dressed in a lab coat). This was in spite of the fact that participants received payment for simply showing up for the research study and could have chosen not to inflict pain or more serious consequences on another person by withdrawing from the study. No one was actually hurt or harmed in any way, Milgram’s experiment was a clever ruse that took advantage of research confederates, those who pretend to be participants in a research study who are actually working for the researcher and have clear, specific directions on how to behave during the research study (Hock, 2009). Milgram’s and others’ studies that involved deception and potential emotional harm to study participants catalyzed the development of ethical guidelines for conducting psychological research that discourage the use of deception of research subjects, unless it can be argued not to cause harm and, in general, requiring informed consent of participants.

Personality Psychology

Another major field of study within the social and personality domain is, of course, personality psychology. Personality refers to the long-standing traits and patterns that propel individuals to consistently think, feel, and behave in specific ways. Our personality is what makes us unique individuals. Each person has an idiosyncratic pattern of enduring, long-term characteristics, and a manner in which they interact with other individuals and the world around them. Our personalities are thought to be long-term, stable, and not easily changed. Personality psychology focuses on

Several individuals (e.g., Freud and Maslow) that we have already discussed in our historical overview of psychology, and the American psychologist Gordon Allport, contributed to early theories of personality. These early theorists attempted to explain how an individual’s personality develops from his or her given perspective. For example, Freud proposed that personality arose as conflicts between the conscious and unconscious parts of the mind were carried out over the lifespan. Specifically, Freud theorized that an individual went through various psychosexual stages of development. According to Freud, adult personality would result from the resolution of various conflicts that centered on the migration of erogenous (or sexual pleasure-producing) zones from the oral (mouth) to the anus to the phallus to the genitals. Like many of Freud’s theories, this particular idea was controversial and did not lend itself to experimental tests (Person, 1980).

More recently, the study of personality has taken on a more quantitative approach. Rather than explaining how personality arises, research is focused on identifying personality traits, measuring these traits, and determining how these traits interact in a particular context to determine how a person will behave in any given situation. Personality traits are relatively consistent patterns of thought and behavior, and many have proposed that five trait dimensions are sufficient to capture the variations in personality seen across individuals. These five dimensions are known as the “Big Five” or the Five Factor model, and include dimensions of conscientiousness, agreeableness, neuroticism, openness, and extraversion (shown below). Each of these traits has been demonstrated to be relatively stable over the lifespan (e.g., Rantanen, Metsäpelto, Feldt, Pulkinnen, and Kokko, 2007; Soldz & Vaillant, 1999; McCrae & Costa, 2008) and is influenced by genetics (e.g., Jang, Livesly, and Vernon, 1996).

A diagram includes five vertically stacked arrows, which point to the left and right. A dimension's first letter, name, and description are included inside of each arrow. A box to the left of each arrow includes traits associated with a low score for that arrow's dimension. A box to the right of each arrow includes traits associated with a high score for that arrow's dimension. The top arrow includes the trait “openness,” which is described with the words, “imagination,” “feelings,” “actions,” and “ideas.” The box to the left of that arrow includes the words, “practical,” “conventional,” and “prefers routine,” while the box to the right of that arrow includes the words, “curious,” “wide range of interests,” and “independent.” The next arrow includes the trait “conscientiousness,” which is described with the words, “competence,” “self-discipline,” “thoughtfulness,” and “goal-driven.” The box to the left of that arrow includes the words, “impulsive,” “careless,” and “disorganized,” while the box to the right of that arrow includes the words, “hardworking,” “dependable,” and “organized.” The next arrow includes the trait “extroversion,” which is described with the words, “sociability,” “assertiveness,” and “emotional expression.” The box to the left of that arrow includes the words, “quiet,” “reserved,” and “withdrawn,” while the box to the right of that arrow includes the words, “outgoing,” “warm,” and “seeks adventure.” The next arrow includes the trait “agreeableness,” which is described with the words, “cooperative,” “trustworthy,” and “good-natured.” The box to the left of that arrow includes the words, “critical,” “uncooperative,” and “suspicious,” while the box to the right of that arrow includes the words, “helpful,” “trusting,” and “empathetic.” The next arrow includes the trait “neuroticism,” which is described as “tendency toward unstable emotions.” The box to the left of that arrow includes the words, “calm,” “even-tempered,” and “secure,” while the box to the right of that arrow includes the words, “anxious,” “unhappy,” and “prone to negative emotions.”"
Figure 3. Each of the dimensions of the Five Factor model is shown in this figure. The provided description would describe someone who scored highly on that given dimension. Someone with a lower score on a given dimension could be described in opposite terms.

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The Mental and Physical Health Domain

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Learning Objectives

  • Describe the basic interests and applications of abnormal, clinical, and health psychology
Image of five pillars, showing the biological, cognitive, developmental, social and personality, and mental and physical health.
Figure 1. The mental and physical health domain of psychology covers mental disorders, treatments for disorders, as well as the study of health and happiness.

This domain of psychology is what many people think of when they think about psychology—mental disorders and counseling. This includes the study of abnormal psychology, with its focus on abnormal thoughts and behaviors, as well as counseling and treatment methods, and recommendations for coping with stress and living a healthy life.

The names and classifications of mental disorders are listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM). The DSM is currently in its 5th edition (DSM-V) and has been designed for use in a wide variety of contexts and across clinical settings (including inpatient, outpatient, partial hospital, clinic, private practice, and primary care). The diagnostic manual includes a total of 237 specific diagnosable disorders, each described in detail, including its symptoms, prevalence, risk factors, and comorbidity. Over time, the number of diagnosable conditions listed in the DSM has grown steadily, prompting criticism from some. Nevertheless, the diagnostic criteria in the DSM are more explicit than those of any other system, which makes the DSM system highly desirable for both clinical diagnosis and research.

Graph of DSM disorders showing lifetime prevalence rates. Major depressive disorder, alcohol abuse, specific phobias, social anxiety disorder, and drug abuse top the list, followed by post-traumatic stress disorder, generalized anxiety disorder, panic disorder, obsessive-compulsive disorder, and dysthymia.
Figure 2. Lifetime prevalence rates for major psychological disorders.

Clinical Psychology

Clinical psychology is the area of psychology that focuses on the diagnosis and treatment of psychological disorders and other problematic patterns of behavior. As such, it is generally considered to be a more applied area within psychology; however, some clinicians are also actively engaged in scientific research. Counseling psychology is a similar discipline that focuses on emotional, social, vocational, and health-related outcomes in individuals who are considered psychologically healthy. As mentioned earlier, both Freud and Rogers provided perspectives that have been influential in shaping how clinicians interact with people seeking psychotherapy. While aspects of the psychoanalytic theory are still found among some of today’s therapists who are trained from a psychodynamic perspective, Roger’s ideas about client-centered therapy have been especially influential in shaping how many clinicians operate. Furthermore, both behaviorism and the cognitive revolution have shaped clinical practice in the forms of behavioral therapy, cognitive therapy, and cognitive-behavioral therapy. Issues related to the diagnosis and treatment of psychological disorders and problematic patterns of behavior will be discussed in detail later in this textbook.
The points of an equilateral triangle are labeled “thoughts,” “behaviors,” and “emotions.” There are arrows running along the sides of the triangle with points on both ends, pointing to the labels.
Figure 3. Cognitive-behavioral therapists take cognitive processes and behaviors into account when providing psychotherapy. This is one of several strategies that may be used by practicing clinical psychologists.

By far, this is the area of psychology that receives the most attention in popular media, and many people mistakenly assume that all psychology is clinical psychology.

Health Psychology

Health psychology focuses on how health is affected by the interaction of biological, psychological, and sociocultural factors. This particular approach is known as the biopsychosocial model. Health psychologists are interested in helping individuals achieve better health through public policy, education, intervention, and research. Health psychologists might conduct research that explores the relationship between one’s genetic makeup, patterns of behavior, relationships, psychological stress, and health. They may research effective ways to motivate people to address patterns of behavior that contribute to poorer health (MacDonald, 2013).

Three circles overlap in the middle. The circles are labeled Biological, Psychological, and Social.
Figure 4. The biopsychosocial model suggests that health/illness is determined by an interaction of these three factors.

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Other Psychological Subfields

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Learning Objectives

  • Define industrial-organizational psychology, sport and exercise psychology, and forensic psychology

Industrial-Organizational Psychology

Industrial-Organizational psychology (I-O psychology) is a subfield of psychology that applies psychological theories, principles, and research findings in industrial and organizational settings. I-O psychologists are often involved in issues related to personnel management, organizational structure, and workplace environment. Businesses often seek the aid of I-O psychologists to make the best hiring decisions as well as to create an environment that results in high levels of employee productivity and efficiency. In addition to its applied nature, I-O psychology also involves conducting scientific research on behavior within I-O settings (Riggio, 2013).

Sport and Exercise Psychology

Researchers in sport and exercise psychology study the psychological aspects of sport performance, including motivation and performance anxiety, and the effects of sport on mental and emotional wellbeing. Research is also conducted on similar topics as they relate to physical exercise in general. The discipline also includes topics that are broader than sport and exercise but that are related to interactions between mental and physical performance under demanding conditions, such as fire fighting, military operations, artistic performance, and surgery.

Forensic Psychology

Forensic psychology is a branch of psychology that deals questions of psychology as they arise in the context of the justice system. For example, forensic psychologists (and forensic psychiatrists) will assess a person’s competency to stand trial, assess the state of mind of a defendant, act as consultants on child custody cases, consult on sentencing and treatment recommendations, and advise on issues such as eyewitness testimony and children’s testimony (American Board of Forensic Psychology, 2014). In these capacities, they will typically act as expert witnesses, called by either side in a court case to provide their research- or experience-based opinions. As expert witnesses, forensic psychologists must have a good understanding of the law and provide information in the context of the legal system rather than just within the realm of psychology. Forensic psychologists are also used in the jury selection process and witness preparation. They may also be involved in providing psychological treatment within the criminal justice system. Criminal profilers are a relatively small proportion of psychologists that act as consultants to law enforcement.

Link to Learning

Check out the APA website for more information on psychological subfields and possible career paths.

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Introduction to Careers in Psychology

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What you’ll learn to do: describe the value of psychology and possible careers paths for those who study psychology

A female captain in the army reads a medical textbook at her desk while conversing with another soldier.
Figure 1. An Army psychologist reviewing medical information.

Generally, academic careers in psychology require doctoral degrees. However, there are a number of nonacademic career options for people who have master’s degrees in psychology. While people with bachelor’s degrees in psychology have more limited psychology-related career options, the skills acquired as a function of an undergraduate education in psychology are useful in a variety of work contexts and are applicable to a wide variety of careers. Basically, studying psychology is never a bad choice!

Learning Objectives

  • Explain why an education in psychology is valuable
  • Describe educational requirements and career options for the study of psychology

Merits of an Education in Psychology

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Learning Objectives

  • Explain why an education in psychology is valuable

Often, students take their first psychology course because they are interested in helping others and want to learn more about themselves and why they act the way they do. Sometimes, students take a psychology course because it either satisfies a general education requirement or is required for a program of study such as nursing or pre-med. Many of these students develop such an interest in the area that they go on to declare psychology as their major. As a result, psychology is one of the most popular majors on college campuses across the United States (Johnson & Lubin, 2011). A number of well-known individuals were psychology majors. Just a few famous names on this list are Facebook’s creator Mark Zuckerberg, television personality and political satirist Jon Stewart, actress Natalie Portman, and filmmaker Wes Craven (Halonen, 2011). About 6 percent of all bachelor degrees granted in the United States are in the discipline of psychology (U.S. Department of Education, 2013).

An education in psychology is valuable for a number of reasons. Psychology students hone critical thinking skills and are trained in the use of the scientific method. Critical thinking is the active application of a set of skills to information for the understanding and evaluation of that information. The evaluation of information—assessing its reliability and usefulness— is an important skill in a world full of competing “facts,” many of which are designed to be misleading. For example, critical thinking involves maintaining an attitude of skepticism, recognizing internal biases, making use of logical thinking, asking appropriate questions, and making observations. Psychology students also can develop better communication skills during the course of their undergraduate coursework (American Psychological Association, 2011). Together, these factors increase students’ scientific literacy and prepare students to critically evaluate the various sources of information they encounter.

In addition to these broad-based skills, psychology students come to understand the complex factors that shape one’s behavior. They appreciate the interaction of our biology, our environment, and our experiences in determining who we are and how we will behave. They learn about basic principles that guide how we think and behave, and they come to recognize the tremendous diversity that exists across individuals and across cultural boundaries (American Psychological Association, 2011).

Watch It

Watch this video from The Psych Show about the benefits and value of studying psychology.

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Think It Over

Why are you taking this course? What do you hope to learn about during this course?

Careers in Psychology

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Learning Objectives

  • Describe educational requirements and career options for the study of psychology
A photograph shows several people are gathered outdoors wearing caps and gowns in a graduation ceremony.
Figure 1. Doctoral degrees are generally conferred in formal ceremonies involving special attire and rites. (credit: Public Affairs Office Fort Wainwright)

Psychologists can work in many different places doing many different things. In general, anyone wishing to continue a career in psychology at a 4-year institution of higher education will have to earn a doctoral degree in psychology for some specialties and at least a master’s degree for others. In most areas of psychology, this means earning a PhD in a relevant area of psychology. Literally, PhD refers to a doctor of philosophy degree, but here, philosophy does not refer to the field of philosophy per se. Rather, philosophy in this context refers to many different disciplinary perspectives that would be housed in a traditional college of liberal arts and sciences.

The requirements to earn a PhD vary from country to country and even from school to school, but usually, individuals earning this degree must complete a dissertation. A dissertation is essentially a long research paper or bundled published articles describing research that was conducted as a part of the candidate’s doctoral training. In the United States, a dissertation generally has to be defended before a committee of expert reviewers before the degree is conferred. Once someone earns her PhD, she may seek a faculty appointment at a college or university. Being on the faculty of a college or university often involves dividing time between teaching, research, and service to the institution and profession. The amount of time spent on each of these primary responsibilities varies dramatically from school to school, and it is not uncommon for faculty to move from place to place in search of the best personal fit among various academic environments. The previous section detailed some of the major areas that are commonly represented in psychology departments around the country; thus, depending on the training received, an individual could be anything from a biological psychologist to a clinical psychologist in an academic setting.

A pie chart is labeled “Percent of 2009 Psychology Doctorates Employed in Different Sectors.” The percentage breakdown is University: 26%, Hospital or health service: 25%, Government/VA medical center: 16%, Business or nonprofit: 10%, Other educational institutions: 8%, and Medical school: 6%, Independent practice: 6%. Beneath the pie chart, the label reads: “Source: Michalski, Kohout, Wicherski, & Hart, 2011.”
Figure 2. Individuals earning a PhD in psychology have a range of employment options.

Other Careers in Academic Settings

Often times, schools offer more courses in psychology than their full-time faculty can teach. In these cases, it is not uncommon to bring in an adjunct faculty member or instructor. Adjunct faculty members and instructors usually have an advanced degree in psychology, but they often have primary careers outside of academia and serve in this role as a secondary job. Alternatively, they may not hold the doctoral degree required by most 4-year institutions and use these opportunities to gain experience in teaching. Furthermore, many 2-year colleges and schools need faculty to teach their courses in psychology. In general, many of the people who pursue careers at these institutions have master’s degrees in psychology, although some PhDs make careers at these institutions as well.

Some people earning PhDs may enjoy research in an academic setting. However, they may not be interested in teaching. These individuals might take on faculty positions that are exclusively devoted to conducting research. This type of position would be more likely an option at large, research-focused universities.

In some areas in psychology, it is common for individuals who have recently earned their PhD to seek out positions in postdoctoral training programs that are available before going on to serve as faculty. In most cases, young scientists will complete one or two postdoctoral programs before applying for a full-time faculty position. Postdoctoral training programs allow young scientists to further develop their research programs and broaden their research skills under the supervision of other professionals in the field.

Career Options Outside of Academics

Individuals who wish to become practicing clinical psychologists have another option for earning a doctoral degree, which is known as a PsyD. A PsyD is a doctor of psychology degree that is increasingly popular among individuals interested in pursuing careers in clinical psychology. PsyD programs generally place less emphasis on research-oriented skills and focus more on application of psychological principles in the clinical context (Norcorss & Castle, 2002).

Regardless of whether earning a PhD or PsyD, in most states, an individual wishing to practice as a licensed clinical or counseling psychologist may complete postdoctoral work under the supervision of a licensed psychologist. Within the last few years, however, several states have begun to remove this requirement, which would allow someone to get an earlier start in his career (Munsey, 2009). After an individual has met the state requirements, his credentials are evaluated to determine whether he can sit for the licensure exam. Only individuals that pass this exam can call themselves licensed clinical or counseling psychologists (Norcross, n.d.). Licensed clinical or counseling psychologists can then work in a number of settings, ranging from private clinical practice to hospital settings. It should be noted that clinical psychologists and psychiatrists do different things and receive different types of education. While both can conduct therapy and counseling, clinical psychologists have a PhD or a PsyD, whereas psychiatrists have a doctor of medicine degree (MD). As such, licensed clinical psychologists can administer and interpret psychological tests, while psychiatrists can prescribe medications.

Individuals earning a PhD can work in a variety of settings, depending on their areas of specialization. For example, someone trained as a biopsychologist might work in a pharmaceutical company to help test the efficacy of a new drug. Someone with a clinical background might become a forensic psychologist and work within the legal system to make recommendations during criminal trials and parole hearings, or serve as an expert in a court case.

While earning a doctoral degree in psychology is a lengthy process, usually taking between 5–6 years of graduate study (DeAngelis, 2010), there are a number of careers that can be attained with a master’s degree in psychology. People who wish to provide psychotherapy can become licensed to serve as various types of professional counselors (Hoffman, 2012). Relevant master’s degrees are also sufficient for individuals seeking careers as school psychologists (National Association of School Psychologists, n.d.), in some capacities related to sport psychology (American Psychological Association, 2014), or as consultants in various industrial settings (Landers, 2011, June 14). Undergraduate coursework in psychology may be applicable to other careers such as psychiatric social work or psychiatric nursing, where assessments and therapy may be a part of the job.

As mentioned in the opening section of this chapter, an undergraduate education in psychology is associated with a knowledge base and skill set that many employers find quite attractive. It should come as no surprise, then, that individuals earning bachelor’s degrees in psychology find themselves in a number of different careers, as shown in the table. Examples of a few such careers can involve serving as case managers, working in sales, working in human resource departments, and teaching in high schools. The rapidly growing realm of healthcare professions is another field in which an education in psychology is helpful and sometimes required. For example, the Medical College Admission Test (MCAT) exam that people must take to be admitted to medical school now includes a section on the psychological foundations of behavior.

Table 1. Top Occupations Employing Graduates with a BA in Psychology (Fogg, Harrington, Harrington, & Shatkin, 2012)
Ranking Occupation
1 Mid- and top-level management (executive, administrator)
2 Sales
3 Social work
4 Other management positions
5 Human resources (personnel, training)
6 Other administrative positions
7 Insurance, real estate, business
8 Marketing and sales
9 Healthcare (nurse, pharmacist, therapist)
10 Finance (accountant, auditor)

Link to Learning

Visit this career website describing some of the career options available to people earning bachelor’s degrees in psychology.

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Think It Over

Which of the career options described in this section is most appealing to you?

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Putting It Together: Psychological Foundations

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Learning Objectives

In this module, you learned to

  • describe the evolution of psychology and the major pioneers in the field
  • identify the various approaches, fields, and subfields of psychology along with their major concepts and important figures
  • describe the value of psychology and possible careers paths for those who study psychology

Psychology is a rapidly growing and ever-evolving field of study. In this module, you learned about its roots in early philosophy and the development of psychology as a distinct field of study in the late 1800s. Since that time, various schools of psychology have dominated the scene at different points in time, from structuralism and functionalism, to Freud’s psychodynamic theory, behaviorism, humanism, and the cognitive revolution. In modern psychology, researchers and practitioners consider some of these historical approaches but also approach the study of mind and behavior through a variety of lenses, including biological, cognitive, developmental, social, and health perspectives.

Watch It

Watch the following Crash Course Psychology video for a good recap of the topics covered in this module:

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You can view the transcript for “Intro to Psychology: Crash Course Psychology #1” here (opens in new window).

Consider a fascinating example of psychological research conducted by is an Assistant Professor of Cognitive Psychology at Oberlin College, Paul Thibodeau. His focus is on language, specifically how people utilize metaphors and analogies, but he did one study on word aversion that he explains in his own words in the following example. As you read it, consider the breadth of coverage that psychologists cover as well as the importance of the scientific method and research to the investigative process. We’ll learn more about experiments and psychological research in the next module, but if you could design a psychological study based on the topics that piqued your interested in this text so far, what would it be? Where do your interests lie? Remember, there are nearly endless possibilities for research within the vast field of psychology, and studying the subject will serve to your advantage, no matter your chosen field or career path.

Word Aversion

If you had to pick the most cringeworthy word in the English language, what would you choose? Many people report that they find words like “moist,” “crevice,” “slacks,” and “luggage” acutely aversive, so maybe you’d pick one of those. For instance, People Magazine recently coined “moist” the “most cringeworthy word” in American English and invited their “sexiest men alive” to try to make it sound “hot” (watch the moist video here).

One writer, in response, described the video as “…pure sadism. It’s torture, it’s rude, and it’s awful…” and claimed that the only way to overcome the experience was to “go Oedipal and gouge your eyes out”. Indeed, readers who find the word “moist” aversive may experience some unpleasantness in reading this paper.

Researcher Paul H. Thibodeau sought to understand how prevalent the aversion to the word “moist” really is, and what makes it so unappealing. He conducted five experiments with over 2,500 participants, and found that about 18% of participants found the word to be aversive. He first hypothesized why people might find the word aversive—is it the sound? Or the connotation and meaning? Or is it due to social expectations and social transmission?

The experiments shows that aversion was most likely due to both social causes and its connotation, as it may be associated with bodily functions. The study found that people who scored highest on their levels of digust toward bodily functions also scored high on their dislike for the word moist. The same people found words like vomit and pleghm to be aversive, but were less affected by similar-sounding words (“hoist”) or by words related to sex.

A bar graph showing mean aversiveness on the y-axis and word type on the x-axis. Those who are moist-averse also showed aversiveness towards semantically-similar words, and bodily-related words.
Figure 1. This graph shows ratings of participants who described themselves as moist-averse and their levels of aversiveness towards words from six different lexical categories—similar-meaning words, similar-sounding words, bodily-related words, sex-related words, and words with either negative or positive associations. Asterisks indicate statistically significant differences at the p < .05 level.

Often when people were asked to describe why they felt aversion toward the word, they mentioned that they didn’t like the way it sounded. The data reveal, however, that people are not averse to phonetically similar words. Interestingly, other people guessed that people felt an aversion to moist because of its association with sex, but the data also reveal that the word’s connection to sex is not what makes it cringeworthy. It’s important to point out here that one reason research is so valuable is that it contradicts common sense notions and helps us better understand human behavior.

Another piece of evidence supporting the social transmission of the word aversion is that in the study, some participants first watched the People Magazine video of celebrities saying “moist,” while others watched a control video. Those who watched the video found the word more aversive, and negative than those who did not. Dr. Thibodeau summarizes lessons learned from the study as follows:Thibodeau, Paul (2016). The “Moist” Conundrum, The Psych Report. Retrieved from http://thepsychreport.com/science/moist-conundrum/

There are a few important lessons to be learned from these studies. Two are fairly obvious: we now have a better sense of what makes the word “moist” aversive and another demonstration that we’re not particularly good at reflecting accurately on why we think what we think.

More relevant to broader theories in psychology, the work has implications for theories of language processing and the psychology of disgust. Emotional language is processed differently than “neutral” language: it grabs our attention, engages different parts of the brain, and is more likely to be remembered. This can be good or bad: cake mixes that advertise themselves as “moist” may make some people more likely to buy them because they catch our eye, but they may make us less likely to buy them because of the word’s association with disgusting bodily function (an open question).

Disgust is adaptive. If we didn’t have an instinct to run away from vomit and diarrhea, disease would spread more easily. But is this instinct biological or do we learn it? Does our culture shape what we find disgusting? This is a complex and nuanced question. Significant work is needed to answer it definitively. But the present studies suggest that, when it comes to the disgust that is elicited by words like “moist,” there is an important cultural component—the symbols we use to communicate with one another can become contaminated and elicit disgust by virtue of their association with bodily functions.

Discussion: Foundations of Psychology

48

Perspectives in Psychology

In this discussion, you will post a minimum THREE times. First, in a primary post of between 200 and 300 words, then at least twice on other posts in the class (of at least 75 words each).

Step 1: In this module, you learned about the five main psychological domains and also covered some of the main perspectives in psychology. Think about some of the various perspectives you learned about (including psychoanalysis, behaviorism, cognitive psychology, humanism, and the biological approach), and explain how an alien psychologist from another planet might explain the following human behaviors:

  1. Why do people cut or shave hair from their bodies (and why does it vary by sex, age, groups, etc.)?
  2. Why do children in an elementary school walk in a line when going to class?
  3. Why are people physically aggressive towards each other (and why might males might be observed doing so more than females)?

Explain each of the three behaviors with a DIFFERENT perspective. Give a well-founded explanation of how a psychologist would explain that behavior from that particular perspective.

Next, write a summary paragraph about which psychological perspective most resonates with you, and why. If you were to practice psychology someday, either as a therapist, counselor, teacher, researcher, or in some other capacity, which perspective do you think you might emphasize?

Step 2: Comment, in posts of at least 75-100 words, on TWO other posts in the discussion. These responses should add to the conversation and contribute to a deeper understanding of the psychological perspective.

Psychological Research

V

Why It Matters: Psychological Research

49

Children sit in front of a bank of television screens. A sign on the wall says, “Some content may not be suitable for children.”
Figure 1. How does television content impact children’s behavior? (credit: modification of work by “antisocialtory”/Flickr)

Have you ever wondered whether the violence you see on television affects your behavior? Are you more likely to behave aggressively in real life after watching people behave violently in dramatic situations on the screen? Or, could seeing fictional violence actually get aggression out of your system, causing you to be more peaceful? How are children influenced by the media they are exposed to? A psychologist interested in the relationship between behavior and exposure to violent images might ask these very questions.

The topic of violence in the media today is contentious. Since ancient times, humans have been concerned about the effects of new technologies on our behaviors and thinking processes. The Greek philosopher Socrates, for example, worried that writing—a new technology at that time—would diminish people’s ability to remember because they could rely on written records rather than committing information to memory. In our world of quickly changing technologies, questions about the effects of media continue to emerge. Is it okay to talk on a cell phone while driving? Are headphones good to use in a car? What impact does text messaging have on reaction time while driving? These are types of questions that psychologist David Strayer asks in his lab.

Watch It

Watch this short video to see how Strayer utilizes the scientific method to reach important conclusions regarding technology and driving safety.

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You can view the transcript for “Understanding driver distraction” here (opens in new window).

How can we go about finding answers that are supported not by mere opinion, but by evidence that we can all agree on? The findings of psychological research can help us navigate issues like this.

Module References

American Academy of Pediatrics, American Academy of Child & Adolescent Psychiatry, American Psychological Association, American Medical Association, American Academy of Family Physicians, American Psychiatric Association. (2000). Joint statement on the impact of entertainment violence on children. Retrieved from http://www2.aap.org/advocacy/releases/jstmtevc.htm.

American Cancer Society. (n.d.). History of the cancer prevention studies. Retrieved from http://www.cancer.org/research/researchtopreventcancer/history-cancer-prevention-study

American Psychological Association. (2009). Publication Manual of the American Psychological Association (6th ed.). Washington, DC: Author.

American Psychological Association. (n.d.). Research with animals in psychology. Retrieved from https://www.apa.org/research/responsible/research-animals.pdf

Arnett, J. (2008). The neglected 95%: Why American psychology needs to become less American. American Psychologist, 63(7), 602–614.

Barton, B. A., Eldridge, A. L., Thompson, D., Affenito, S. G., Striegel-Moore, R. H., Franko, D. L., . . . Crockett, S. J. (2005). The relationship of breakfast and cereal consumption to nutrient intake and body mass index: The national heart, lung, and blood institute growth and health study. Journal of the American Dietetic Association, 105(9), 1383–1389. Retrieved from http://dx.doi.org/10.1016/j.jada.2005.06.003

Chwalisz, K., Diener, E., & Gallagher, D. (1988). Autonomic arousal feedback and emotional experience: Evidence from the spinal cord injured. Journal of Personality and Social Psychology, 54, 820–828.

Clayton, R. R., Cattarello, A. M., & Johnstone, B. M. (1996). The effectiveness of Drug Abuse Resistance Education (Project DARE): 5-year follow-up results. Preventive Medicine: An International Journal Devoted to Practice and Theory, 25(3), 307–318. doi:10.1006/pmed.1996.0061

D.A.R.E. (n.d.). D.A.R.E. is substance abuse prevention education and much more! [About page] Retrieved from http://www.dare.org/about-d-a-r-e/

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Ennett, S. T., Tobler, N. S., Ringwalt, C. L., & Flewelling, R. L. (1994). How effective is drug abuse resistance education? A meta-analysis of Project DARE outcome evaluations. American Journal of Public Health, 84(9), 1394–1401. doi:10.2105/AJPH.84.9.1394

Fanger, S. M., Frankel, L. A., & Hazen, N. (2012). Peer exclusion in preschool children’s play: Naturalistic observations in a playground setting. Merrill-Palmer Quarterly, 58, 224–254.

Fiedler, K. (2004). Illusory correlation. In R. F. Pohl (Ed.), Cognitive illusions: A handbook on fallacies and biases in thinking, judgment and memory (pp. 97–114). New York, NY: Psychology Press.

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Jenkins, W. J., Ruppel, S. E., Kizer, J. B., Yehl, J. L., & Griffin, J. L. (2012). An examination of post 9-11 attitudes towards Arab Americans. North American Journal of Psychology, 14, 77–84.

Jones, J. M. (2013, May 13). Same-sex marriage support solidifies above 50% in U.S. Gallup Politics. Retrieved from http://www.gallup.com/poll/162398/sex-marriage-support-solidifies-above.aspx

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Introduction to The Scientific Method

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What you’ll learn to do: define and apply the scientific method to psychology

photograph of the word "research" from a dictionary with a pen pointing at the word.

Scientists are engaged in explaining and understanding how the world around them works, and they are able to do so by coming up with theories that generate hypotheses that are testable and falsifiable. Theories that stand up to their tests are retained and refined, while those that do not are discarded or modified. In this way, research enables scientists to separate fact from simple opinion. Having good information generated from research aids in making wise decisions both in public policy and in our personal lives. In this section, you’ll see how psychologists use the scientific method to study and understand behavior.

Learning Objectives

  • Explain the steps of the scientific method
  • Describe why the scientific method is important to psychology
  • Summarize the processes of informed consent and debriefing
  • Explain how research involving humans or animals is regulated

The Scientific Process

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Learning Objectives

  • Explain the steps of the scientific method
  • Differentiate between theories and hypotheses
Scientific research is a critical tool for successfully navigating our complex world. Without it, we would be forced to rely solely on intuition, other people’s authority, and blind luck. While many of us feel confident in our abilities to decipher and interact with the world around us, history is filled with examples of how very wrong we can be when we fail to recognize the need for evidence in supporting claims. At various times in history, we would have been certain that the sun revolved around a flat earth, that the earth’s continents did not move, and that mental illness was caused by possession (Figure 1). It is through systematic scientific research that we divest ourselves of our preconceived notions and superstitions and gain an objective understanding of ourselves and our world.
A skull has a large hole bored through the forehead.
Figure 1. Some of our ancestors, across the world and over the centuries, believed that trephination—the practice of making a hole in the skull, as shown here—allowed evil spirits to leave the body, thus curing mental illness and other disorders. (credit: “taiproject”/Flickr)

The goal of all scientists is to better understand the world around them. Psychologists focus their attention on understanding behavior, as well as the cognitive (mental) and physiological (body) processes that underlie behavior. In contrast to other methods that people use to understand the behavior of others, such as intuition and personal experience, the hallmark of scientific research is that there is evidence to support a claim. Scientific knowledge is empirical: It is grounded in objective, tangible evidence that can be observed time and time again, regardless of who is observing.

While behavior is observable, the mind is not. If someone is crying, we can see the behavior. However, the reason for the behavior is more difficult to determine. Is the person crying due to being sad, in pain, or happy? Sometimes we can learn the reason for someone’s behavior by simply asking a question, like “Why are you crying?” However, there are situations in which an individual is either uncomfortable or unwilling to answer the question honestly, or is incapable of answering. For example, infants would not be able to explain why they are crying. In such circumstances, the psychologist must be creative in finding ways to better understand behavior. This module explores how scientific knowledge is generated, and how important that knowledge is in forming decisions in our personal lives and in the public domain.

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Process of Scientific Research

Flowchart of the scientific method. It begins with make an observation, then ask a question, form a hypothesis that answers the question, make a prediction based on the hypothesis, do an experiment to test the prediction, analyze the results, prove the hypothesis correct or incorrect, then report the results.
Figure 2. The scientific method is a process for gathering data and processing information. It provides well-defined steps to standardize how scientific knowledge is gathered through a logical, rational problem-solving method.

Scientific knowledge is advanced through a process known as the scientific method. Basically, ideas (in the form of theories and hypotheses) are tested against the real world (in the form of empirical observations), and those empirical observations lead to more ideas that are tested against the real world, and so on.

The basic steps in the scientific method are:

  • Observe a natural phenomenon and define a question about it
  • Make a hypothesis, or potential solution to the question
  • Test the hypothesis
  • If the hypothesis is true, find more evidence or find counter-evidence
  • If the hypothesis is false, create a new hypothesis or try again
  • Draw conclusions and repeat–the scientific method is never-ending, and no result is ever considered perfect

In order to ask an important question that may improve our understanding of the world, a researcher must first observe natural phenomena. By making observations, a researcher can define a useful question. After finding a question to answer, the researcher can then make a prediction (a hypothesis) about what he or she thinks the answer will be. This prediction is usually a statement about the relationship between two or more variables. After making a hypothesis, the researcher will then design an experiment to test his or her hypothesis and evaluate the data gathered. These data will either support or refute the hypothesis. Based on the conclusions drawn from the data, the researcher will then find more evidence to support the hypothesis, look for counter-evidence to further strengthen the hypothesis, revise the hypothesis and create a new experiment, or continue to incorporate the information gathered to answer the research question.

Basic Principles of the Scientific Method

Two key concepts in the scientific approach are theory and hypothesis. A theory is a well-developed set of ideas that propose an explanation for observed phenomena that can be used to make predictions about future observations. A hypothesis is a testable prediction that is arrived at logically from a theory. It is often worded as an if-then statement (e.g., if I study all night, I will get a passing grade on the test). The hypothesis is extremely important because it bridges the gap between the realm of ideas and the real world. As specific hypotheses are tested, theories are modified and refined to reflect and incorporate the result of these tests.

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A diagram has four boxes: the top is labeled “theory,” the right is labeled “hypothesis,” the bottom is labeled “research,” and the left is labeled “observation.” Arrows flow in the direction from top to right to bottom to left and back to the top, clockwise. The top right arrow is labeled “use the hypothesis to form a theory,” the bottom right arrow is labeled “design a study to test the hypothesis,” the bottom left arrow is labeled “perform the research,” and the top left arrow is labeled “create or modify the theory.”
Figure 3. The scientific method of research includes proposing hypotheses, conducting research, and creating or modifying theories based on results.

Other key components in following the scientific method include verifiability, predictability, falsifiability, and fairness. Verifiability means that an experiment must be replicable by another researcher. To achieve verifiability, researchers must make sure to document their methods and clearly explain how their experiment is structured and why it produces certain results.

Predictability in a scientific theory implies that the theory should enable us to make predictions about future events. The precision of these predictions is a measure of the strength of the theory.

Falsifiability refers to whether a hypothesis can be disproved. For a hypothesis to be falsifiable, it must be logically possible to make an observation or do a physical experiment that would show that there is no support for the hypothesis. Even when a hypothesis cannot be shown to be false, that does not necessarily mean it is not valid. Future testing may disprove the hypothesis. This does not mean that a hypothesis has to be shown to be false, just that it can be tested.

To determine whether a hypothesis is supported or not supported, psychological researchers must conduct hypothesis testing using statistics. Hypothesis testing is a type of statistics that determines the probability of a hypothesis being true or false. If hypothesis testing reveals that results were “statistically significant,” this means that there was support for the hypothesis and that the researchers can be reasonably confident that their result was not due to random chance. If the results are not statistically significant, this means that the researchers’ hypothesis was not supported.

Fairness implies that all data must be considered when evaluating a hypothesis. A researcher cannot pick and choose what data to keep and what to discard or focus specifically on data that support or do not support a particular hypothesis. All data must be accounted for, even if they invalidate the hypothesis.

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Applying the Scientific Method

To see how this process works, let’s consider a specific theory and a hypothesis that might be generated from that theory. As you’ll learn in a later module, the James-Lange theory of emotion asserts that emotional experience relies on the physiological arousal associated with the emotional state. If you walked out of your home and discovered a very aggressive snake waiting on your doorstep, your heart would begin to race and your stomach churn. According to the James-Lange theory, these physiological changes would result in your feeling of fear. A hypothesis that could be derived from this theory might be that a person who is unaware of the physiological arousal that the sight of the snake elicits will not feel fear.

Remember that a good scientific hypothesis is falsifiable, or capable of being shown to be incorrect. Recall from the introductory module that Sigmund Freud had lots of interesting ideas to explain various human behaviors (Figure 3). However, a major criticism of Freud’s theories is that many of his ideas are not falsifiable; for example, it is impossible to imagine empirical observations that would disprove the existence of the id, the ego, and the superego—the three elements of personality described in Freud’s theories. Despite this, Freud’s theories are widely taught in introductory psychology texts because of their historical significance for personality psychology and psychotherapy, and these remain the root of all modern forms of therapy.

(a)A photograph shows Freud holding a cigar. (b) The mind’s conscious and unconscious states are illustrated as an iceberg floating in water. Beneath the water’s surface in the “unconscious” area are the id, ego, and superego. The area just below the water’s surface is labeled “preconscious.” The area above the water’s surface is labeled “conscious.”
Figure 4. Many of the specifics of (a) Freud’s theories, such as (b) his division of the mind into id, ego, and superego, have fallen out of favor in recent decades because they are not falsifiable. In broader strokes, his views set the stage for much of psychological thinking today, such as the unconscious nature of the majority of psychological processes.

In contrast, the James-Lange theory does generate falsifiable hypotheses, such as the one described above. Some individuals who suffer significant injuries to their spinal columns are unable to feel the bodily changes that often accompany emotional experiences. Therefore, we could test the hypothesis by determining how emotional experiences differ between individuals who have the ability to detect these changes in their physiological arousal and those who do not. In fact, this research has been conducted and while the emotional experiences of people deprived of an awareness of their physiological arousal may be less intense, they still experience emotion (Chwalisz, Diener, & Gallagher, 1988).

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Link to Learning

Want to participate in a study? Visit this Psychological Research on the Net website and click on a link that sounds interesting to you in order to participate in online research.

Why the Scientific Method Is Important for Psychology

The use of the scientific method is one of the main features that separates modern psychology from earlier philosophical inquiries about the mind. Compared to chemistry, physics, and other “natural sciences,” psychology has long been considered one of the “social sciences” because of the subjective nature of the things it seeks to study. Many of the concepts that psychologists are interested in—such as aspects of the human mind, behavior, and emotions—are subjective and cannot be directly measured. Psychologists often rely instead on behavioral observations and self-reported data, which are considered by some to be illegitimate or lacking in methodological rigor. Applying the scientific method to psychology, therefore, helps to standardize the approach to understanding its very different types of information.

The scientific method allows psychological data to be replicated and confirmed in many instances, under different circumstances, and by a variety of researchers. Through replication of experiments, new generations of psychologists can reduce errors and broaden the applicability of theories. It also allows theories to be tested and validated instead of simply being conjectures that could never be verified or falsified. All of this allows psychologists to gain a stronger understanding of how the human mind works.

Scientific articles published in journals and psychology papers written in the style of the American Psychological Association (i.e., in “APA style”) are structured around the scientific method. These papers include an Introduction, which introduces the background information and outlines the hypotheses; a Methods section, which outlines the specifics of how the experiment was conducted to test the hypothesis; a Results section, which includes the statistics that tested the hypothesis and state whether it was supported or not supported, and a Discussion and Conclusion, which state the implications of finding support for, or no support for, the hypothesis. Writing articles and papers that adhere to the scientific method makes it easy for future researchers to repeat the study and attempt to replicate the results.

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Ethics in Research

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Learning Objectives

  • Explain how research involving humans and animals is regulated

Today, scientists agree that good research is ethical in nature and is guided by a basic respect for human dignity and safety. However, as you will read in the Tuskegee Syphilis Study, this has not always been the case. Modern researchers must demonstrate that the research they perform is ethically sound. This section presents how ethical considerations affect the design and implementation of research conducted today.

Research Involving Human Participants

Any experiment involving the participation of human subjects is governed by extensive, strict guidelines designed to ensure that the experiment does not result in harm. Any research institution that receives federal support for research involving human participants must have access to an institutional review board (IRB). The IRB is a committee of individuals often made up of members of the institution’s administration, scientists, and community members (Figure 1). The purpose of the IRB is to review proposals for research that involves human participants. The IRB reviews these proposals with the principles mentioned above in mind, and generally, approval from the IRB is required in order for the experiment to proceed.

A photograph shows a group of people seated around tables in a meeting room.
Figure 1. An institution’s IRB meets regularly to review experimental proposals that involve human participants. (credit: modification of work by Lowndes Area Knowledge Exchange (LAKE)/Flickr)

An institution’s IRB requires several components in any experiment it approves. For one, each participant must sign an informed consent form before they can participate in the experiment. An informed consent form provides a written description of what participants can expect during the experiment, including potential risks and implications of the research. It also lets participants know that their involvement is completely voluntary and can be discontinued without penalty at any time. Furthermore, the informed consent guarantees that any data collected in the experiment will remain completely confidential. In cases where research participants are under the age of 18, the parents or legal guardians are required to sign the informed consent form.

While the informed consent form should be as honest as possible in describing exactly what participants will be doing, sometimes deception is necessary to prevent participants’ knowledge of the exact research question from affecting the results of the study. Deception involves purposely misleading experiment participants in order to maintain the integrity of the experiment, but not to the point where the deception could be considered harmful. For example, if we are interested in how our opinion of someone is affected by their attire, we might use deception in describing the experiment to prevent that knowledge from affecting participants’ responses. In cases where deception is involved, participants must receive a full debriefing upon conclusion of the study—complete, honest information about the purpose of the experiment, how the data collected will be used, the reasons why deception was necessary, and information about how to obtain additional information about the study.

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Dig Deeper: Ethics and the Tuskegee Syphilis Study

Unfortunately, the ethical guidelines that exist for research today were not always applied in the past. In 1932, poor, rural, black, male sharecroppers from Tuskegee, Alabama, were recruited to participate in an experiment conducted by the U.S. Public Health Service, with the aim of studying syphilis in black men (Figure 2). In exchange for free medical care, meals, and burial insurance, 600 men agreed to participate in the study. A little more than half of the men tested positive for syphilis, and they served as the experimental group (given that the researchers could not randomly assign participants to groups, this represents a quasi-experiment). The remaining syphilis-free individuals served as the control group. However, those individuals that tested positive for syphilis were never informed that they had the disease.

While there was no treatment for syphilis when the study began, by 1947 penicillin was recognized as an effective treatment for the disease. Despite this, no penicillin was administered to the participants in this study, and the participants were not allowed to seek treatment at any other facilities if they continued in the study. Over the course of 40 years, many of the participants unknowingly spread syphilis to their wives (and subsequently their children born from their wives) and eventually died because they never received treatment for the disease. This study was discontinued in 1972 when the experiment was discovered by the national press (Tuskegee University, n.d.). The resulting outrage over the experiment led directly to the National Research Act of 1974 and the strict ethical guidelines for research on humans described in this chapter. Why is this study unethical? How were the men who participated and their families harmed as a function of this research?

A photograph shows a person administering an injection.
Figure 2. A participant in the Tuskegee Syphilis Study receives an injection.

Research Involving Animal Subjects

Many psychologists conduct research involving animal subjects. Often, these researchers use rodents (Figure 3) or birds as the subjects of their experiments—the APA estimates that 90% of all animal research in psychology uses these species (American Psychological Association, n.d.). Because many basic processes in animals are sufficiently similar to those in humans, these animals are acceptable substitutes for research that would be considered unethical in human participants.
A photograph shows a rat.
Figure 3. Rats, like the one shown here, often serve as the subjects of animal research.

This does not mean that animal researchers are immune to ethical concerns. Indeed, the humane and ethical treatment of animal research subjects is a critical aspect of this type of research. Researchers must design their experiments to minimize any pain or distress experienced by animals serving as research subjects.

Whereas IRBs review research proposals that involve human participants, animal experimental proposals are reviewed by an Institutional Animal Care and Use Committee (IACUC). An IACUC consists of institutional administrators, scientists, veterinarians, and community members. This committee is charged with ensuring that all experimental proposals require the humane treatment of animal research subjects. It also conducts semi-annual inspections of all animal facilities to ensure that the research protocols are being followed. No animal research project can proceed without the committee’s approval.

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Introduction to Approaches to Research

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What you’ll learn to do: describe the strengths and weaknesses of descriptive, experimental, and correlational research

Three researchers review data while talking around a microscope.

If you think about the vast array of fields and topics covered in psychology, you understand that in order to do psychological research, there must be a diverse set of ways to gather data and perform experiments. For example, a biological psychologist might work predominately in a lab setting or alongside a neurologist. A social scientist may set up situational experiments, a health psychologist may administer surveys, and a developmental psychologist may make observations in a classroom. In this section, you’ll learn about the various types of research methods that psychologists employ to learn about human behavior.

Psychologists use descriptive, experimental, and correlational methods to conduct research. Descriptive, or qualitative, methods include the case study, naturalistic observation, surveys, archival research, longitudinal research, and cross-sectional research.

Experiments are conducted in order to determine cause-and-effect relationships. In ideal experimental design, the only difference between the experimental and control groups is whether participants are exposed to the experimental manipulation. Each group goes through all phases of the experiment, but each group will experience a different level of the independent variable: the experimental group is exposed to the experimental manipulation, and the control group is not exposed to the experimental manipulation. The researcher then measures the changes that are produced in the dependent variable in each group. Once data is collected from both groups, it is analyzed statistically to determine if there are meaningful differences between the groups.

When scientists passively observe and measure phenomena it is called correlational research. Here, psychologists do not intervene and change behavior, as they do in experiments. In correlational research, they identify patterns of relationships, but usually cannot infer what causes what. Importantly, with correlational research, you can examine only two variables at a time, no more and no less.

Watch It: More on Research

If you enjoy learning through lectures and want an interesting and comprehensive summary of this section, then click on the Youtube link to watch a lecture given by MIT Professor John Gabrieli. Start at the 30:45 minute mark and watch through the end to hear examples of actual psychological studies and how they were analyzed. Listen for references to independent and dependent variables, experimenter bias, and double-blind studies. In the lecture, you’ll learn about breaking social norms, “WEIRD” research, why expectations matter, how a warm cup of coffee might make you nicer, why you should change your answer on a multiple choice test, and why praise for intelligence won’t make you any smarter.

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You can view the transcript for “Lec 2 | MIT 9.00SC Introduction to Psychology, Spring 2011” here (opens in new window).

Learning Objectives

  • Differentiate between descriptive, experimental, and correlational research
  • Explain the strengths and weaknesses of case studies, naturalistic observation, and surveys
  • Describe the strength and weaknesses of archival research
  • Compare longitudinal and cross-sectional approaches to research
  • Explain what a correlation coefficient tells us about the relationship between variables
  • Describe why correlation does not mean causation
  • Describe the experimental process, including ways to control for bias
  • Identify and differentiate between independent and dependent variables

Descriptive Research

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Learning Objectives

  • Differentiate between descriptive, experimental, and correlational research
  • Explain the strengths and weaknesses of case studies, naturalistic observation, and surveys

There are many research methods available to psychologists in their efforts to understand, describe, and explain behavior and the cognitive and biological processes that underlie it. Some methods rely on observational techniques. Other approaches involve interactions between the researcher and the individuals who are being studied—ranging from a series of simple questions to extensive, in-depth interviews—to well-controlled experiments.

The three main categories of psychological research are descriptive, correlational, and experimental research. Research studies that do not test specific relationships between variables are called descriptive, or qualitative, studies. These studies are used to describe general or specific behaviors and attributes that are observed and measured. In the early stages of research it might be difficult to form a hypothesis, especially when there is not any existing literature in the area. In these situations designing an experiment would be premature, as the question of interest is not yet clearly defined as a hypothesis. Often a researcher will begin with a non-experimental approach, such as a descriptive study, to gather more information about the topic before designing an experiment or correlational study to address a specific hypothesis. Descriptive research is distinct from correlational research, in which psychologists formally test whether a relationship exists between two or more variables. Experimental research goes a step further beyond descriptive and correlational research and randomly assigns people to different conditions, using hypothesis testing to make inferences about how these conditions affect behavior. It aims to determine if one variable directly impacts and causes another. Correlational and experimental research both typically use hypothesis testing, whereas descriptive research does not.

Each of these research methods has unique strengths and weaknesses, and each method may only be appropriate for certain types of research questions. For example, studies that rely primarily on observation produce incredible amounts of information, but the ability to apply this information to the larger population is somewhat limited because of small sample sizes. Survey research, on the other hand, allows researchers to easily collect data from relatively large samples. While this allows for results to be generalized to the larger population more easily, the information that can be collected on any given survey is somewhat limited and subject to problems associated with any type of self-reported data. Some researchers conduct archival research by using existing records. While this can be a fairly inexpensive way to collect data that can provide insight into a number of research questions, researchers using this approach have no control on how or what kind of data was collected.

Correlational research can find a relationship between two variables, but the only way a researcher can claim that the relationship between the variables is cause and effect is to perform an experiment. In experimental research, which will be discussed later in the text, there is a tremendous amount of control over variables of interest. While this is a powerful approach, experiments are often conducted in very artificial settings. This calls into question the validity of experimental findings with regard to how they would apply in real-world settings. In addition, many of the questions that psychologists would like to answer cannot be pursued through experimental research because of ethical concerns.

The three main types of descriptive studies are case studies, naturalistic observation, and surveys.

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Case Studies

In 2011, the New York Times published a feature story on Krista and Tatiana Hogan, Canadian twin girls. These particular twins are unique because Krista and Tatiana are conjoined twins, connected at the head. There is evidence that the two girls are connected in a part of the brain called the thalamus, which is a major sensory relay center. Most incoming sensory information is sent through the thalamus before reaching higher regions of the cerebral cortex for processing.

Link to Learning

To learn more about Krista and Tatiana, watch this video about their lives as conjoined twins.

The implications of this potential connection mean that it might be possible for one twin to experience the sensations of the other twin. For instance, if Krista is watching a particularly funny television program, Tatiana might smile or laugh even if she is not watching the program. This particular possibility has piqued the interest of many neuroscientists who seek to understand how the brain uses sensory information.

These twins represent an enormous resource in the study of the brain, and since their condition is very rare, it is likely that as long as their family agrees, scientists will follow these girls very closely throughout their lives to gain as much information as possible (Dominus, 2011).

In observational research, scientists are conducting a clinical or case study when they focus on one person or just a few individuals. Indeed, some scientists spend their entire careers studying just 10–20 individuals. Why would they do this? Obviously, when they focus their attention on a very small number of people, they can gain a tremendous amount of insight into those cases. The richness of information that is collected in clinical or case studies is unmatched by any other single research method. This allows the researcher to have a very deep understanding of the individuals and the particular phenomenon being studied.

If clinical or case studies provide so much information, why are they not more frequent among researchers? As it turns out, the major benefit of this particular approach is also a weakness. As mentioned earlier, this approach is often used when studying individuals who are interesting to researchers because they have a rare characteristic. Therefore, the individuals who serve as the focus of case studies are not like most other people. If scientists ultimately want to explain all behavior, focusing attention on such a special group of people can make it difficult to generalize any observations to the larger population as a whole. Generalizing refers to the ability to apply the findings of a particular research project to larger segments of society. Again, case studies provide enormous amounts of information, but since the cases are so specific, the potential to apply what’s learned to the average person may be very limited.

Try It

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Naturalistic Observation

If you want to understand how behavior occurs, one of the best ways to gain information is to simply observe the behavior in its natural context. However, people might change their behavior in unexpected ways if they know they are being observed. How do researchers obtain accurate information when people tend to hide their natural behavior? As an example, imagine that your professor asks everyone in your class to raise their hand if they always wash their hands after using the restroom. Chances are that almost everyone in the classroom will raise their hand, but do you think hand washing after every trip to the restroom is really that universal?

This is very similar to the phenomenon mentioned earlier in this module: many individuals do not feel comfortable answering a question honestly. But if we are committed to finding out the facts about hand washing, we have other options available to us.

Suppose we send a classmate into the restroom to actually watch whether everyone washes their hands after using the restroom. Will our observer blend into the restroom environment by wearing a white lab coat, sitting with a clipboard, and staring at the sinks? We want our researcher to be inconspicuous—perhaps standing at one of the sinks pretending to put in contact lenses while secretly recording the relevant information. This type of observational study is called naturalistic observation: observing behavior in its natural setting. To better understand peer exclusion, Suzanne Fanger collaborated with colleagues at the University of Texas to observe the behavior of preschool children on a playground. How did the observers remain inconspicuous over the duration of the study? They equipped a few of the children with wireless microphones (which the children quickly forgot about) and observed while taking notes from a distance. Also, the children in that particular preschool (a “laboratory preschool”) were accustomed to having observers on the playground (Fanger, Frankel, & Hazen, 2012).

A photograph shows two police cars driving, one with its lights flashing.
Figure 1. Seeing a police car behind you would probably affect your driving behavior. (credit: Michael Gil)

It is critical that the observer be as unobtrusive and as inconspicuous as possible: when people know they are being watched, they are less likely to behave naturally. If you have any doubt about this, ask yourself how your driving behavior might differ in two situations: In the first situation, you are driving down a deserted highway during the middle of the day; in the second situation, you are being followed by a police car down the same deserted highway (Figure 1).

It should be pointed out that naturalistic observation is not limited to research involving humans. Indeed, some of the best-known examples of naturalistic observation involve researchers going into the field to observe various kinds of animals in their own environments. As with human studies, the researchers maintain their distance and avoid interfering with the animal subjects so as not to influence their natural behaviors. Scientists have used this technique to study social hierarchies and interactions among animals ranging from ground squirrels to gorillas. The information provided by these studies is invaluable in understanding how those animals organize socially and communicate with one another. The anthropologist Jane Goodall, for example, spent nearly five decades observing the behavior of chimpanzees in Africa (Figure 2). As an illustration of the types of concerns that a researcher might encounter in naturalistic observation, some scientists criticized Goodall for giving the chimps names instead of referring to them by numbers—using names was thought to undermine the emotional detachment required for the objectivity of the study (McKie, 2010).

(a) A photograph shows Jane Goodall speaking from a lectern. (b) A photograph shows a chimpanzee’s face.
Figure 2. (a) Jane Goodall made a career of conducting naturalistic observations of (b) chimpanzee behavior. (credit “Jane Goodall”: modification of work by Erik Hersman; “chimpanzee”: modification of work by “Afrika Force”/Flickr.com)

The greatest benefit of naturalistic observation is the validity, or accuracy, of information collected unobtrusively in a natural setting. Having individuals behave as they normally would in a given situation means that we have a higher degree of ecological validity, or realism, than we might achieve with other research approaches. Therefore, our ability to generalize the findings of the research to real-world situations is enhanced. If done correctly, we need not worry about people or animals modifying their behavior simply because they are being observed. Sometimes, people may assume that reality programs give us a glimpse into authentic human behavior. However, the principle of inconspicuous observation is violated as reality stars are followed by camera crews and are interviewed on camera for personal confessionals. Given that environment, we must doubt how natural and realistic their behaviors are.

The major downside of naturalistic observation is that they are often difficult to set up and control. In our restroom study, what if you stood in the restroom all day prepared to record people’s hand washing behavior and no one came in? Or, what if you have been closely observing a troop of gorillas for weeks only to find that they migrated to a new place while you were sleeping in your tent? The benefit of realistic data comes at a cost. As a researcher you have no control of when (or if) you have behavior to observe. In addition, this type of observational research often requires significant investments of time, money, and a good dose of luck.

Sometimes studies involve structured observation. In these cases, people are observed while engaging in set, specific tasks. An excellent example of structured observation comes from Strange Situation by Mary Ainsworth (you will read more about this in the module on lifespan development). The Strange Situation is a procedure used to evaluate attachment styles that exist between an infant and caregiver. In this scenario, caregivers bring their infants into a room filled with toys. The Strange Situation involves a number of phases, including a stranger coming into the room, the caregiver leaving the room, and the caregiver’s return to the room. The infant’s behavior is closely monitored at each phase, but it is the behavior of the infant upon being reunited with the caregiver that is most telling in terms of characterizing the infant’s attachment style with the caregiver.

Another potential problem in observational research is observer bias. Generally, people who act as observers are closely involved in the research project and may unconsciously skew their observations to fit their research goals or expectations. To protect against this type of bias, researchers should have clear criteria established for the types of behaviors recorded and how those behaviors should be classified. In addition, researchers often compare observations of the same event by multiple observers, in order to test inter-rater reliability: a measure of reliability that assesses the consistency of observations by different observers.

Try It

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Surveys

Often, psychologists develop surveys as a means of gathering data. Surveys are lists of questions to be answered by research participants, and can be delivered as paper-and-pencil questionnaires, administered electronically, or conducted verbally (Figure 3). Generally, the survey itself can be completed in a short time, and the ease of administering a survey makes it easy to collect data from a large number of people.

Surveys allow researchers to gather data from larger samples than may be afforded by other research methods. A sample is a subset of individuals selected from a population, which is the overall group of individuals that the researchers are interested in. Researchers study the sample and seek to generalize their findings to the population.

A sample online survey reads, “Dear visitor, your opinion is important to us. We would like to invite you to participate in a short survey to gather your opinions and feedback on your news consumption habits. The survey will take approximately 10-15 minutes. Simply click the “Yes” button below to launch the survey. Would you like to participate?” Two buttons are labeled “yes” and “no.”
Figure 3. Surveys can be administered in a number of ways, including electronically administered research, like the survey shown here. (credit: Robert Nyman)

There is both strength and weakness of the survey in comparison to case studies. By using surveys, we can collect information from a larger sample of people. A larger sample is better able to reflect the actual diversity of the population, thus allowing better generalizability. Therefore, if our sample is sufficiently large and diverse, we can assume that the data we collect from the survey can be generalized to the larger population with more certainty than the information collected through a case study. However, given the greater number of people involved, we are not able to collect the same depth of information on each person that would be collected in a case study.

Another potential weakness of surveys is something we touched on earlier in this module: people don’t always give accurate responses. They may lie, misremember, or answer questions in a way that they think makes them look good. For example, people may report drinking less alcohol than is actually the case.

Any number of research questions can be answered through the use of surveys. One real-world example is the research conducted by Jenkins, Ruppel, Kizer, Yehl, and Griffin (2012) about the backlash against the US Arab-American community following the terrorist attacks of September 11, 2001. Jenkins and colleagues wanted to determine to what extent these negative attitudes toward Arab-Americans still existed nearly a decade after the attacks occurred. In one study, 140 research participants filled out a survey with 10 questions, including questions asking directly about the participant’s overt prejudicial attitudes toward people of various ethnicities. The survey also asked indirect questions about how likely the participant would be to interact with a person of a given ethnicity in a variety of settings (such as, “How likely do you think it is that you would introduce yourself to a person of Arab-American descent?”). The results of the research suggested that participants were unwilling to report prejudicial attitudes toward any ethnic group. However, there were significant differences between their pattern of responses to questions about social interaction with Arab-Americans compared to other ethnic groups: they indicated less willingness for social interaction with Arab-Americans compared to the other ethnic groups. This suggested that the participants harbored subtle forms of prejudice against Arab-Americans, despite their assertions that this was not the case (Jenkins et al., 2012).

Try It

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Think It Over

A friend of yours is working part-time in a local pet store. Your friend has become increasingly interested in how dogs normally communicate and interact with each other, and is thinking of visiting a local veterinary clinic to see how dogs interact in the waiting room. After reading this section, do you think this is the best way to better understand such interactions? Do you have any suggestions that might result in more valid data?

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Other Types of Descriptive Research

55

Learning Objectives

  • Describe the strength and weaknesses of archival, longitudinal, and cross-sectional research
Other types of descriptive research include archival research and longitudinal and cross-sectional studies.

Archival Research

Some researchers gain access to large amounts of data without interacting with a single research participant. Instead, they use existing records to answer various research questions. This type of research approach is known as archival research. Archival research relies on looking at past records or data sets to look for interesting patterns or relationships.

For example, a researcher might access the academic records of all individuals who enrolled in college within the past ten years and calculate how long it took them to complete their degrees, as well as course loads, grades, and extracurricular involvement. Archival research could provide important information about who is most likely to complete their education, and it could help identify important risk factors for struggling students (Figure 1).

(a) A photograph shows stacks of paper files on shelves. (b) A photograph shows a computer.
Figure 1. A researcher doing archival research examines records, whether archived as a (a) hardcopy or (b) electronically. (credit “paper files”: modification of work by “Newtown graffiti”/Flickr; “computer”: modification of work by INPIVIC Family/Flickr)

In comparing archival research to other research methods, there are several important distinctions. For one, the researcher employing archival research never directly interacts with research participants. Therefore, the investment of time and money to collect data is considerably less with archival research. Additionally, researchers have no control over what information was originally collected. Therefore, research questions have to be tailored so they can be answered within the structure of the existing data sets. There is also no guarantee of consistency between the records from one source to another, which might make comparing and contrasting different data sets problematic.

Longitudinal and Cross-Sectional Research

Sometimes we want to see how people change over time, as in studies of human development and lifespan. When we test the same group of individuals repeatedly over an extended period of time, we are conducting longitudinal research. Longitudinal research is a research design in which data-gathering is administered repeatedly over an extended period of time. For example, we may survey a group of individuals about their dietary habits at age 20, retest them a decade later at age 30, and then again at age 40.

Another approach is cross-sectional research. In cross-sectional research, a researcher compares multiple segments of the population at the same time. Using the dietary habits example above, the researcher might directly compare different groups of people by age. Instead of observing a group of people for 20 years to see how their dietary habits changed from decade to decade, the researcher would study a group of 20-year-old individuals and compare them to a group of 30-year-old individuals and a group of 40-year-old individuals. While cross-sectional research requires a shorter-term investment, it is also limited by differences that exist between the different generations (or cohorts) that have nothing to do with age per se, but rather reflect the social and cultural experiences of different generations of individuals make them different from one another.

To illustrate this concept, consider the following survey findings. In recent years there has been significant growth in the popular support of same-sex marriage. Many studies on this topic break down survey participants into different age groups. In general, younger people are more supportive of same-sex marriage than are those who are older (Jones, 2013). Does this mean that as we age we become less open to the idea of same-sex marriage, or does this mean that older individuals have different perspectives because of the social climates in which they grew up? Longitudinal research is a powerful approach because the same individuals are involved in the research project over time, which means that the researchers need to be less concerned with differences among cohorts affecting the results of their study.

Often longitudinal studies are employed when researching various diseases in an effort to understand particular risk factors. Such studies often involve tens of thousands of individuals who are followed for several decades. Given the enormous number of people involved in these studies, researchers can feel confident that their findings can be generalized to the larger population. The Cancer Prevention Study-3 (CPS-3) is one of a series of longitudinal studies sponsored by the American Cancer Society aimed at determining predictive risk factors associated with cancer. When participants enter the study, they complete a survey about their lives and family histories, providing information on factors that might cause or prevent the development of cancer. Then every few years the participants receive additional surveys to complete. In the end, hundreds of thousands of participants will be tracked over 20 years to determine which of them develop cancer and which do not.

Clearly, this type of research is important and potentially very informative. For instance, earlier longitudinal studies sponsored by the American Cancer Society provided some of the first scientific demonstrations of the now well-established links between increased rates of cancer and smoking (American Cancer Society, n.d.) (Figure 2).

A photograph shows pack of cigarettes and cigarettes in an ashtray. The pack of cigarettes reads, “Surgeon general’s warning: smoking causes lung cancer, heart disease, emphysema, and may complicate pregnancy.”
Figure 2. Longitudinal research like the CPS-3 help us to better understand how smoking is associated with cancer and other diseases. (credit: CDC/Debora Cartagena)

As with any research strategy, longitudinal research is not without limitations. For one, these studies require an incredible time investment by the researcher and research participants. Given that some longitudinal studies take years, if not decades, to complete, the results will not be known for a considerable period of time. In addition to the time demands, these studies also require a substantial financial investment. Many researchers are unable to commit the resources necessary to see a longitudinal project through to the end.

Research participants must also be willing to continue their participation for an extended period of time, and this can be problematic. People move, get married and take new names, get ill, and eventually die. Even without significant life changes, some people may simply choose to discontinue their participation in the project. As a result, the attrition rates, or reduction in the number of research participants due to dropouts, in longitudinal studies are quite high and increases over the course of a project. For this reason, researchers using this approach typically recruit many participants fully expecting that a substantial number will drop out before the end. As the study progresses, they continually check whether the sample still represents the larger population, and make adjustments as necessary.

Try It

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https://pressbooks.online.ucf.edu/lumenpsychology/?p=137

An interactive or media element has been excluded from this version of the text. You can view it online here:
https://pressbooks.online.ucf.edu/lumenpsychology/?p=137

Correlational Research

56

Learning Objectives

  • Explain what a correlation coefficient tells us about the relationship between variables
  • Describe why correlation does not mean causation

Did you know that as sales in ice cream increase, so does the overall rate of crime? Is it possible that indulging in your favorite flavor of ice cream could send you on a crime spree? Or, after committing crime do you think you might decide to treat yourself to a cone? There is no question that a relationship exists between ice cream and crime (e.g., Harper, 2013), but it would be pretty foolish to decide that one thing actually caused the other to occur.

It is much more likely that both ice cream sales and crime rates are related to the temperature outside. When the temperature is warm, there are lots of people out of their houses, interacting with each other, getting annoyed with one another, and sometimes committing crimes. Also, when it is warm outside, we are more likely to seek a cool treat like ice cream. How do we determine if there is indeed a relationship between two things? And when there is a relationship, how can we discern whether it is attributable to coincidence or causation?

Correlational Research

Correlation means that there is a relationship between two or more variables (such as ice cream consumption and crime), but this relationship does not necessarily imply cause and effect. When two variables are correlated, it simply means that as one variable changes, so does the other. We can measure correlation by calculating a statistic known as a correlation coefficient. A correlation coefficient is a number from -1 to +1 that indicates the strength and direction of the relationship between variables. The correlation coefficient is usually represented by the letter r.

The number portion of the correlation coefficient indicates the strength of the relationship. The closer the number is to 1 (be it negative or positive), the more strongly related the variables are, and the more predictable changes in one variable will be as the other variable changes. The closer the number is to zero, the weaker the relationship, and the less predictable the relationships between the variables becomes. For instance, a correlation coefficient of 0.9 indicates a far stronger relationship than a correlation coefficient of 0.3. If the variables are not related to one another at all, the correlation coefficient is 0. The example above about ice cream and crime is an example of two variables that we might expect to have no relationship to each other.

The sign—positive or negative—of the correlation coefficient indicates the direction of the relationship (Figure 1). A positive correlation means that the variables move in the same direction. Put another way, it means that as one variable increases so does the other, and conversely, when one variable decreases so does the other. A negative correlation means that the variables move in opposite directions. If two variables are negatively correlated, a decrease in one variable is associated with an increase in the other and vice versa.

The example of ice cream and crime rates is a positive correlation because both variables increase when temperatures are warmer. Other examples of positive correlations are the relationship between an individual’s height and weight or the relationship between a person’s age and number of wrinkles. One might expect a negative correlation to exist between someone’s tiredness during the day and the number of hours they slept the previous night: the amount of sleep decreases as the feelings of tiredness increase. In a real-world example of negative correlation, student researchers at the University of Minnesota found a weak negative correlation (r = -0.29) between the average number of days per week that students got fewer than 5 hours of sleep and their GPA (Lowry, Dean, & Manders, 2010). Keep in mind that a negative correlation is not the same as no correlation. For example, we would probably find no correlation between hours of sleep and shoe size.

As mentioned earlier, correlations have predictive value. Imagine that you are on the admissions committee of a major university. You are faced with a huge number of applications, but you are able to accommodate only a small percentage of the applicant pool. How might you decide who should be admitted? You might try to correlate your current students’ college GPA with their scores on standardized tests like the SAT or ACT. By observing which correlations were strongest for your current students, you could use this information to predict relative success of those students who have applied for admission into the university.

Three scatterplots are shown. Scatterplot (a) is labeled “positive correlation” and shows scattered dots forming a rough line from the bottom left to the top right; the x-axis is labeled “weight” and the y-axis is labeled “height.” Scatterplot (b) is labeled “negative correlation” and shows scattered dots forming a rough line from the top left to the bottom right; the x-axis is labeled “tiredness” and the y-axis is labeled “hours of sleep.” Scatterplot (c) is labeled “no correlation” and shows scattered dots having no pattern; the x-axis is labeled “shoe size” and the y-axis is labeled “hours of sleep.”
Figure 1. Scatterplots are a graphical view of the strength and direction of correlations. The stronger the correlation, the closer the data points are to a straight line. In these examples, we see that there is (a) a positive correlation between weight and height, (b) a negative correlation between tiredness and hours of sleep, and (c) no correlation between shoe size and hours of sleep.

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Correlation Does Not Indicate Causation

Correlational research is useful because it allows us to discover the strength and direction of relationships that exist between two variables. However, correlation is limited because establishing the existence of a relationship tells us little about cause and effect. While variables are sometimes correlated because one does cause the other, it could also be that some other factor, a confounding variable, is actually causing the systematic movement in our variables of interest. In the ice cream/crime rate example mentioned earlier, temperature is a confounding variable that could account for the relationship between the two variables.

Even when we cannot point to clear confounding variables, we should not assume that a correlation between two variables implies that one variable causes changes in another. This can be frustrating when a cause-and-effect relationship seems clear and intuitive. Think back to our discussion of the research done by the American Cancer Society and how their research projects were some of the first demonstrations of the link between smoking and cancer. It seems reasonable to assume that smoking causes cancer, but if we were limited to correlational research, we would be overstepping our bounds by making this assumption.

Unfortunately, people mistakenly make claims of causation as a function of correlations all the time. Such claims are especially common in advertisements and news stories. For example, recent research found that people who eat cereal on a regular basis achieve healthier weights than those who rarely eat cereal (Frantzen, Treviño, Echon, Garcia-Dominic, & DiMarco, 2013; Barton et al., 2005). Guess how the cereal companies report this finding. Does eating cereal really cause an individual to maintain a healthy weight, or are there other possible explanations, such as, someone at a healthy weight is more likely to regularly eat a healthy breakfast than someone who is obese or someone who avoids meals in an attempt to diet (Figure 2)? While correlational research is invaluable in identifying relationships among variables, a major limitation is the inability to establish causality. Psychologists want to make statements about cause and effect, but the only way to do that is to conduct an experiment to answer a research question. The next section describes how scientific experiments incorporate methods that eliminate, or control for, alternative explanations, which allow researchers to explore how changes in one variable cause changes in another variable.

Try It

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Watch It

Watch this clip from Freakonomics for an example of how correlation does not indicate causation.

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You can view the transcript for “Correlation vs. Causality: Freakonomics Movie” here (opens in new window).

A photograph shows a bowl of cereal.
Figure 2. Does eating cereal really cause someone to be a healthy weight? (credit: Tim Skillern)

Illusory Correlations

The temptation to make erroneous cause-and-effect statements based on correlational research is not the only way we tend to misinterpret data. We also tend to make the mistake of illusory correlations, especially with unsystematic observations. Illusory correlations, or false correlations, occur when people believe that relationships exist between two things when no such relationship exists. One well-known illusory correlation is the supposed effect that the moon’s phases have on human behavior. Many people passionately assert that human behavior is affected by the phase of the moon, and specifically, that people act strangely when the moon is full (Figure 3).

A photograph shows the moon.
Figure 3. Some people believe that a full moon makes people behave oddly. (credit: Cory Zanker)

There is no denying that the moon exerts a powerful influence on our planet. The ebb and flow of the ocean’s tides are tightly tied to the gravitational forces of the moon. Many people believe, therefore, that it is logical that we are affected by the moon as well. After all, our bodies are largely made up of water. A meta-analysis of nearly 40 studies consistently demonstrated, however, that the relationship between the moon and our behavior does not exist (Rotton & Kelly, 1985). While we may pay more attention to odd behavior during the full phase of the moon, the rates of odd behavior remain constant throughout the lunar cycle.

Why are we so apt to believe in illusory correlations like this? Often we read or hear about them and simply accept the information as valid. Or, we have a hunch about how something works and then look for evidence to support that hunch, ignoring evidence that would tell us our hunch is false; this is known as confirmation bias. Other times, we find illusory correlations based on the information that comes most easily to mind, even if that information is severely limited. And while we may feel confident that we can use these relationships to better understand and predict the world around us, illusory correlations can have significant drawbacks. For example, research suggests that illusory correlations—in which certain behaviors are inaccurately attributed to certain groups—are involved in the formation of prejudicial attitudes that can ultimately lead to discriminatory behavior (Fiedler, 2004).

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Think It Over

We all have a tendency to make illusory correlations from time to time. Try to think of an illusory correlation that is held by you, a family member, or a close friend. How do you think this illusory correlation came about and what can be done in the future to combat them?

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Experiments

57

Learning Objectives

  • Describe the experimental process, including ways to control for bias
  • Identify and differentiate between independent and dependent variables

Causality: Conducting Experiments and Using the Data

As you’ve learned, the only way to establish that there is a cause-and-effect relationship between two variables is to conduct a scientific experiment. Experiment has a different meaning in the scientific context than in everyday life. In everyday conversation, we often use it to describe trying something for the first time, such as experimenting with a new hair style or a new food. However, in the scientific context, an experiment has precise requirements for design and implementation.

Experimental Hypothesis

In order to conduct an experiment, a researcher must have a specific hypothesis to be tested. As you’ve learned, hypotheses can be formulated either through direct observation of the real world or after careful review of previous research. For example, if you think that children should not be allowed to watch violent programming on television because doing so would cause them to behave more violently, then you have basically formulated a hypothesis—namely, that watching violent television programs causes children to behave more violently. How might you have arrived at this particular hypothesis? You may have younger relatives who watch cartoons featuring characters using martial arts to save the world from evildoers, with an impressive array of punching, kicking, and defensive postures. You notice that after watching these programs for a while, your young relatives mimic the fighting behavior of the characters portrayed in the cartoon (Figure 1).

A photograph shows a child pointing a toy gun.
Figure 1. Seeing behavior like this right after a child watches violent television programming might lead you to hypothesize that viewing violent television programming leads to an increase in the display of violent behaviors. (credit: Emran Kassim)

These sorts of personal observations are what often lead us to formulate a specific hypothesis, but we cannot use limited personal observations and anecdotal evidence to rigorously test our hypothesis. Instead, to find out if real-world data supports our hypothesis, we have to conduct an experiment.

Designing an Experiment

The most basic experimental design involves two groups: the experimental group and the control group. The two groups are designed to be the same except for one difference— experimental manipulation. The experimental group gets the experimental manipulation—that is, the treatment or variable being tested (in this case, violent TV images)—and the control group does not. Since experimental manipulation is the only difference between the experimental and control groups, we can be sure that any differences between the two are due to experimental manipulation rather than chance.

In our example of how violent television programming might affect violent behavior in children, we have the experimental group view violent television programming for a specified time and then measure their violent behavior. We measure the violent behavior in our control group after they watch nonviolent television programming for the same amount of time. It is important for the control group to be treated similarly to the experimental group, with the exception that the control group does not receive the experimental manipulation. Therefore, we have the control group watch non-violent television programming for the same amount of time as the experimental group.

We also need to precisely define, or operationalize, what is considered violent and nonviolent. An operational definition is a description of how we will measure our variables, and it is important in allowing others understand exactly how and what a researcher measures in a particular experiment. In operationalizing violent behavior, we might choose to count only physical acts like kicking or punching as instances of this behavior, or we also may choose to include angry verbal exchanges. Whatever we determine, it is important that we operationalize violent behavior in such a way that anyone who hears about our study for the first time knows exactly what we mean by violence. This aids peoples’ ability to interpret our data as well as their capacity to repeat our experiment should they choose to do so.

Once we have operationalized what is considered violent television programming and what is considered violent behavior from our experiment participants, we need to establish how we will run our experiment. In this case, we might have participants watch a 30-minute television program (either violent or nonviolent, depending on their group membership) before sending them out to a playground for an hour where their behavior is observed and the number and type of violent acts is recorded.

Ideally, the people who observe and record the children’s behavior are unaware of who was assigned to the experimental or control group, in order to control for experimenter bias. Experimenter bias refers to the possibility that a researcher’s expectations might skew the results of the study. Remember, conducting an experiment requires a lot of planning, and the people involved in the research project have a vested interest in supporting their hypotheses. If the observers knew which child was in which group, it might influence how much attention they paid to each child’s behavior as well as how they interpreted that behavior. By being blind to which child is in which group, we protect against those biases. This situation is a single-blind study, meaning that one of the groups (participants) are unaware as to which group they are in (experiment or control group) while the researcher who developed the experiment knows which participants are in each group.

A photograph shows three glass bottles of pills labeled as placebos.
Figure 2. Providing the control group with a placebo treatment protects against bias caused by expectancy. (credit: Elaine and Arthur Shapiro)

In a double-blind study, both the researchers and the participants are blind to group assignments. Why would a researcher want to run a study where no one knows who is in which group? Because by doing so, we can control for both experimenter and participant expectations. If you are familiar with the phrase placebo effect, you already have some idea as to why this is an important consideration. The placebo effect occurs when people’s expectations or beliefs influence or determine their experience in a given situation. In other words, simply expecting something to happen can actually make it happen.

The placebo effect is commonly described in terms of testing the effectiveness of a new medication. Imagine that you work in a pharmaceutical company, and you think you have a new drug that is effective in treating depression. To demonstrate that your medication is effective, you run an experiment with two groups: The experimental group receives the medication, and the control group does not. But you don’t want participants to know whether they received the drug or not.

Why is that? Imagine that you are a participant in this study, and you have just taken a pill that you think will improve your mood. Because you expect the pill to have an effect, you might feel better simply because you took the pill and not because of any drug actually contained in the pill—this is the placebo effect.

To make sure that any effects on mood are due to the drug and not due to expectations, the control group receives a placebo (in this case a sugar pill). Now everyone gets a pill, and once again neither the researcher nor the experimental participants know who got the drug and who got the sugar pill. Any differences in mood between the experimental and control groups can now be attributed to the drug itself rather than to experimenter bias or participant expectations (Figure 2).

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Independent and Dependent Variables

In a research experiment, we strive to study whether changes in one thing cause changes in another. To achieve this, we must pay attention to two important variables, or things that can be changed, in any experimental study: the independent variable and the dependent variable. An independent variable is manipulated or controlled by the experimenter. In a well-designed experimental study, the independent variable is the only important difference between the experimental and control groups. In our example of how violent television programs affect children’s display of violent behavior, the independent variable is the type of program—violent or nonviolent—viewed by participants in the study (Figure 3). A dependent variable is what the researcher measures to see how much effect the independent variable had. In our example, the dependent variable is the number of violent acts displayed by the experimental participants.

A box labeled “independent variable: type of television programming viewed” contains a photograph of a person shooting an automatic weapon. An arrow labeled “influences change in the…” leads to a second box. The second box is labeled “dependent variable: violent behavior displayed” and has a photograph of a child pointing a toy gun.
Figure 3. In an experiment, manipulations of the independent variable are expected to result in changes in the dependent variable. (credit “automatic weapon”: modification of work by Daniel Oines; credit “toy gun”: modification of work by Emran Kassim)

We expect that the dependent variable will change as a function of the independent variable. In other words, the dependent variable depends on the independent variable. A good way to think about the relationship between the independent and dependent variables is with this question: What effect does the independent variable have on the dependent variable? Returning to our example, what effect does watching a half hour of violent television programming or nonviolent television programming have on the number of incidents of physical aggression displayed on the playground?

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Selecting and Assigning Experimental Participants

Now that our study is designed, we need to obtain a sample of individuals to include in our experiment. Our study involves human participants so we need to determine who to include. Participants are the subjects of psychological research, and as the name implies, individuals who are involved in psychological research actively participate in the process. Often, psychological research projects rely on college students to serve as participants. In fact, the vast majority of research in psychology subfields has historically involved students as research participants (Sears, 1986; Arnett, 2008). But are college students truly representative of the general population? College students tend to be younger, more educated, more liberal, and less diverse than the general population. Although using students as test subjects is an accepted practice, relying on such a limited pool of research participants can be problematic because it is difficult to generalize findings to the larger population.

Our hypothetical experiment involves children, and we must first generate a sample of child participants. Samples are used because populations are usually too large to reasonably involve every member in our particular experiment (Figure 4). If possible, we should use a random sample (there are other types of samples, but for the purposes of this section, we will focus on random samples). A random sample is a subset of a larger population in which every member of the population has an equal chance of being selected. Random samples are preferred because if the sample is large enough we can be reasonably sure that the participating individuals are representative of the larger population. This means that the percentages of characteristics in the sample—sex, ethnicity, socioeconomic level, and any other characteristics that might affect the results—are close to those percentages in the larger population.

In our example, let’s say we decide our population of interest is fourth graders. But all fourth graders is a very large population, so we need to be more specific; instead we might say our population of interest is all fourth graders in a particular city. We should include students from various income brackets, family situations, races, ethnicities, religions, and geographic areas of town. With this more manageable population, we can work with the local schools in selecting a random sample of around 200 fourth graders who we want to participate in our experiment.

In summary, because we cannot test all of the fourth graders in a city, we want to find a group of about 200 that reflects the composition of that city. With a representative group, we can generalize our findings to the larger population without fear of our sample being biased in some way.

(a) A photograph shows an aerial view of crowds on a street. (b) A photograph shows s small group of children.
Figure 4. Researchers may work with (a) a large population or (b) a sample group that is a subset of the larger population. (credit “crowd”: modification of work by James Cridland; credit “students”: modification of work by Laurie Sullivan)

Now that we have a sample, the next step of the experimental process is to split the participants into experimental and control groups through random assignment. With random assignment, all participants have an equal chance of being assigned to either group. There is statistical software that will randomly assign each of the fourth graders in the sample to either the experimental or the control group.

Random assignment is critical for sound experimental design. With sufficiently large samples, random assignment makes it unlikely that there are systematic differences between the groups. So, for instance, it would be very unlikely that we would get one group composed entirely of males, a given ethnic identity, or a given religious ideology. This is important because if the groups were systematically different before the experiment began, we would not know the origin of any differences we find between the groups: Were the differences preexisting, or were they caused by manipulation of the independent variable? Random assignment allows us to assume that any differences observed between experimental and control groups result from the manipulation of the independent variable.

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Issues to Consider

While experiments allow scientists to make cause-and-effect claims, they are not without problems. True experiments require the experimenter to manipulate an independent variable, and that can complicate many questions that psychologists might want to address. For instance, imagine that you want to know what effect sex (the independent variable) has on spatial memory (the dependent variable). Although you can certainly look for differences between males and females on a task that taps into spatial memory, you cannot directly control a person’s sex. We categorize this type of research approach as quasi-experimental and recognize that we cannot make cause-and-effect claims in these circumstances.

Experimenters are also limited by ethical constraints. For instance, you would not be able to conduct an experiment designed to determine if experiencing abuse as a child leads to lower levels of self-esteem among adults. To conduct such an experiment, you would need to randomly assign some experimental participants to a group that receives abuse, and that experiment would be unethical.

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Introduction to Statistical Thinking

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What you’ll learn to do: define basic elements of a statistical investigation

A normal distribution curve drawn on top of a histogram.

Once a psychologist has performed an experiment or study and gathered her results, she needs to organize the information in a way so that she can draw conclusions from the results. What does the information mean? Does it support or reject the hypothesis? Is the data valid and reliable, and is the study replicable?

Psychologists use statistics to assist them in analyzing data, and also to give more precise measurements to describe whether something is statistically significant. Analyzing data using statistics enables researchers to find patterns, make claims, and share their results with others. In this section, you’ll learn about some of the tools that psychologists use in statistical analysis.

Learning Objectives

  • Define reliability and validity
  • Describe the importance of distributional thinking and the role of p-values in statistical inference
  • Describe the role of random sampling and random assignment in drawing cause-and-effect conclusions
  • Describe the basic structure of a psychological research article

The Reliability and Validity of Research

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Learning Objectives

  • Define reliability and validity

Interpreting Experimental Findings

Once data is collected from both the experimental and the control groups, a statistical analysis is conducted to find out if there are meaningful differences between the two groups. A statistical analysis determines how likely any difference found is due to chance (and thus not meaningful). In psychology, group differences are considered meaningful, or significant, if the odds that these differences occurred by chance alone are 5 percent or less. Stated another way, if we repeated this experiment 100 times, we would expect to find the same results at least 95 times out of 100.

The greatest strength of experiments is the ability to assert that any significant differences in the findings are caused by the independent variable. This occurs because random selection, random assignment, and a design that limits the effects of both experimenter bias and participant expectancy should create groups that are similar in composition and treatment. Therefore, any difference between the groups is attributable to the independent variable, and now we can finally make a causal statement. If we find that watching a violent television program results in more violent behavior than watching a nonviolent program, we can safely say that watching violent television programs causes an increase in the display of violent behavior.

Reporting Research

When psychologists complete a research project, they generally want to share their findings with other scientists. The American Psychological Association (APA) publishes a manual detailing how to write a paper for submission to scientific journals. Unlike an article that might be published in a magazine like Psychology Today, which targets a general audience with an interest in psychology, scientific journals generally publish peer-reviewed journal articles aimed at an audience of professionals and scholars who are actively involved in research themselves.

Link to Learning

The Online Writing Lab (OWL) at Purdue University can walk you through the APA writing guidelines.

A peer-reviewed journal article is read by several other scientists (generally anonymously) with expertise in the subject matter. These peer reviewers provide feedback—to both the author and the journal editor—regarding the quality of the draft. Peer reviewers look for a strong rationale for the research being described, a clear description of how the research was conducted, and evidence that the research was conducted in an ethical manner. They also look for flaws in the study’s design, methods, and statistical analyses. They check that the conclusions drawn by the authors seem reasonable given the observations made during the research. Peer reviewers also comment on how valuable the research is in advancing the discipline’s knowledge. This helps prevent unnecessary duplication of research findings in the scientific literature and, to some extent, ensures that each research article provides new information. Ultimately, the journal editor will compile all of the peer reviewer feedback and determine whether the article will be published in its current state (a rare occurrence), published with revisions, or not accepted for publication.

Peer review provides some degree of quality control for psychological research. Poorly conceived or executed studies can be weeded out, and even well-designed research can be improved by the revisions suggested. Peer review also ensures that the research is described clearly enough to allow other scientists to replicate it, meaning they can repeat the experiment using different samples to determine reliability. Sometimes replications involve additional measures that expand on the original finding. In any case, each replication serves to provide more evidence to support the original research findings. Successful replications of published research make scientists more apt to adopt those findings, while repeated failures tend to cast doubt on the legitimacy of the original article and lead scientists to look elsewhere. For example, it would be a major advancement in the medical field if a published study indicated that taking a new drug helped individuals achieve a healthy weight without changing their diet. But if other scientists could not replicate the results, the original study’s claims would be questioned.

Dig Deeper: The Vaccine-Autism Myth and the Retraction of Published Studies

Some scientists have claimed that routine childhood vaccines cause some children to develop autism, and, in fact, several peer-reviewed publications published research making these claims. Since the initial reports, large-scale epidemiological research has suggested that vaccinations are not responsible for causing autism and that it is much safer to have your child vaccinated than not. Furthermore, several of the original studies making this claim have since been retracted.

A published piece of work can be rescinded when data is called into question because of falsification, fabrication, or serious research design problems. Once rescinded, the scientific community is informed that there are serious problems with the original publication. Retractions can be initiated by the researcher who led the study, by research collaborators, by the institution that employed the researcher, or by the editorial board of the journal in which the article was originally published. In the vaccine-autism case, the retraction was made because of a significant conflict of interest in which the leading researcher had a financial interest in establishing a link between childhood vaccines and autism (Offit, 2008). Unfortunately, the initial studies received so much media attention that many parents around the world became hesitant to have their children vaccinated (Figure 1). For more information about how the vaccine/autism story unfolded, as well as the repercussions of this story, take a look at Paul Offit’s book, Autism’s False Prophets: Bad Science, Risky Medicine, and the Search for a Cure.

A photograph shows a child being given an oral vaccine.
Figure 1. Some people still think vaccinations cause autism. (credit: modification of work by UNICEF Sverige)

Reliability and Validity

Reliability and validity are two important considerations that must be made with any type of data collection. Reliability refers to the ability to consistently produce a given result. In the context of psychological research, this would mean that any instruments or tools used to collect data do so in consistent, reproducible ways. Unfortunately, being consistent in measurement does not necessarily mean that you have measured something correctly. This is where validity comes into play. Validity refers to the extent to which a given instrument or tool accurately measures what it’s supposed to measure. While any valid measure is by necessity reliable, the reverse is not necessarily true. Researchers strive to use instruments that are both highly reliable and valid.

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Everyday Connection: How Valid Is the SAT?

Standardized tests like the SAT are supposed to measure an individual’s aptitude for a college education, but how reliable and valid are such tests? Research conducted by the College Board suggests that scores on the SAT have high predictive validity for first-year college students’ GPA (Kobrin, Patterson, Shaw, Mattern, & Barbuti, 2008). In this context, predictive validity refers to the test’s ability to effectively predict the GPA of college freshmen. Given that many institutions of higher education require the SAT for admission, this high degree of predictive validity might be comforting.

However, the emphasis placed on SAT scores in college admissions has generated some controversy on a number of fronts. For one, some researchers assert that the SAT is a biased test that places minority students at a disadvantage and unfairly reduces the likelihood of being admitted into a college (Santelices & Wilson, 2010). Additionally, some research has suggested that the predictive validity of the SAT is grossly exaggerated in how well it is able to predict the GPA of first-year college students. In fact, it has been suggested that the SAT’s predictive validity may be overestimated by as much as 150% (Rothstein, 2004). Many institutions of higher education are beginning to consider de-emphasizing the significance of SAT scores in making admission decisions (Rimer, 2008).

In 2014, College Board president David Coleman expressed his awareness of these problems, recognizing that college success is more accurately predicted by high school grades than by SAT scores. To address these concerns, he has called for significant changes to the SAT exam (Lewin, 2014).

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Statistical Significance

60

Learning Objectives

  • Describe the importance of distributional thinking and the role of p-values in statistical inference

Introduction to Statistical Thinking

Coffee cup with heart shaped cream inside.
Figure 1. People around the world differ in their preferences for drinking coffee versus drinking tea. Would the results of the coffee study be the same in Canada as in China? [Image: Duncan, https://goo.gl/vbMyTm, CC BY-NC 2.0, https://goo.gl/l8UUGY]

Does drinking coffee actually increase your life expectancy? A recent study (Freedman, Park, Abnet, Hollenbeck, & Sinha, 2012) found that men who drank at least six cups of coffee a day also had a 10% lower chance of dying (women’s chances were 15% lower) than those who drank none. Does this mean you should pick up or increase your own coffee habit? We will explore these results in more depth in the next section about drawing conclusions from statistics. Modern society has become awash in studies such as this; you can read about several such studies in the news every day.

Conducting such a study well, and interpreting the results of such studies requires understanding basic ideas of statistics, the science of gaining insight from data. Key components to a statistical investigation are:

Notice that the numerical analysis (“crunching numbers” on the computer) comprises only a small part of overall statistical investigation. In this section, you will see how we can answer some of these questions and what questions you should be asking about any statistical investigation you read about.

Distributional Thinking

When data are collected to address a particular question, an important first step is to think of meaningful ways to organize and examine the data. Let’s take a look at an example.

Example 1: Researchers investigated whether cancer pamphlets are written at an appropriate level to be read and understood by cancer patients (Short, Moriarty, & Cooley, 1995). Tests of reading ability were given to 63 patients. In addition, readability level was determined for a sample of 30 pamphlets, based on characteristics such as the lengths of words and sentences in the pamphlet. The results, reported in terms of grade levels, are displayed in Figure 2.

Table showing patients' reading levels and pahmphlet's reading levels.
Figure 2. Frequency tables of patient reading levels and pamphlet readability levels.
Testing these two variables reveal two fundamental aspects of statistical thinking:

Addressing the research question of whether the cancer pamphlets are written at appropriate levels for the cancer patients requires comparing the two distributions. A naïve comparison might focus only on the centers of the distributions. Both medians turn out to be ninth grade, but considering only medians ignores the variability and the overall distributions of these data. A more illuminating approach is to compare the entire distributions, for example with a graph, as in Figure 3.

Bar graph showing that the reading level of pamphlets is typically higher than the reading level of the patients.
Figure 3. Comparison of patient reading levels and pamphlet readability levels.

Figure 2 makes clear that the two distributions are not well aligned at all. The most glaring discrepancy is that many patients (17/63, or 27%, to be precise) have a reading level below that of the most readable pamphlet. These patients will need help to understand the information provided in the cancer pamphlets. Notice that this conclusion follows from considering the distributions as a whole, not simply measures of center or variability, and that the graph contrasts those distributions more immediately than the frequency tables.

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Finding Significance in Data

Even when we find patterns in data, often there is still uncertainty in various aspects of the data. For example, there may be potential for measurement errors (even your own body temperature can fluctuate by almost 1°F over the course of the day). Or we may only have a “snapshot” of observations from a more long-term process or only a small subset of individuals from the population of interest. In such cases, how can we determine whether patterns we see in our small set of data is convincing evidence of a systematic phenomenon in the larger process or population? Let’s take a look at another example.

Example 2: In a study reported in the November 2007 issue of Nature, researchers investigated whether pre-verbal infants take into account an individual’s actions toward others in evaluating that individual as appealing or aversive (Hamlin, Wynn, & Bloom, 2007). In one component of the study, 10-month-old infants were shown a “climber” character (a piece of wood with “googly” eyes glued onto it) that could not make it up a hill in two tries. Then the infants were shown two scenarios for the climber’s next try, one where the climber was pushed to the top of the hill by another character (“helper”), and one where the climber was pushed back down the hill by another character (“hinderer”). The infant was alternately shown these two scenarios several times. Then the infant was presented with two pieces of wood (representing the helper and the hinderer characters) and asked to pick one to play with.

The researchers found that of the 16 infants who made a clear choice, 14 chose to play with the helper toy. One possible explanation for this clear majority result is that the helping behavior of the one toy increases the infants’ likelihood of choosing that toy. But are there other possible explanations? What about the color of the toy? Well, prior to collecting the data, the researchers arranged so that each color and shape (red square and blue circle) would be seen by the same number of infants. Or maybe the infants had right-handed tendencies and so picked whichever toy was closer to their right hand?

Well, prior to collecting the data, the researchers arranged it so half the infants saw the helper toy on the right and half on the left. Or, maybe the shapes of these wooden characters (square, triangle, circle) had an effect? Perhaps, but again, the researchers controlled for this by rotating which shape was the helper toy, the hinderer toy, and the climber. When designing experiments, it is important to control for as many variables as might affect the responses as possible. It is beginning to appear that the researchers accounted for all the other plausible explanations. But there is one more important consideration that cannot be controlled—if we did the study again with these 16 infants, they might not make the same choices. In other words, there is some randomness inherent in their selection process.

P-value

Maybe each infant had no genuine preference at all, and it was simply “random luck” that led to 14 infants picking the helper toy. Although this random component cannot be controlled, we can apply a probability model to investigate the pattern of results that would occur in the long run if random chance were the only factor.

If the infants were equally likely to pick between the two toys, then each infant had a 50% chance of picking the helper toy. It’s like each infant tossed a coin, and if it landed heads, the infant picked the helper toy. So if we tossed a coin 16 times, could it land heads 14 times? Sure, it’s possible, but it turns out to be very unlikely. Getting 14 (or more) heads in 16 tosses is about as likely as tossing a coin and getting 9 heads in a row. This probability is referred to as a p-value. The p-value represents the likelihood that experimental results happened by chance. Within psychology, the most common standard for p-values is “p < .05”. What this means is that there is less than a 5% probability that the results happened just by random chance, and therefore a 95% probability that the results reflect a meaningful pattern in human psychology. We call this statistical significance.

So, in the study above, if we assume that each infant was choosing equally, then the probability that 14 or more out of 16 infants would choose the helper toy is found to be 0.0021. We have only two logical possibilities: either the infants have a genuine preference for the helper toy, or the infants have no preference (50/50) and an outcome that would occur only 2 times in 1,000 iterations happened in this study. Because this p-value of 0.0021 is quite small, we conclude that the study provides very strong evidence that these infants have a genuine preference for the helper toy.

If we compare the p-value to some cut-off value, like 0.05, we see that the p=value is smaller. Because the p-value is smaller than that cut-off value, then we reject the hypothesis that only random chance was at play here. In this case, these researchers would conclude that significantly more than half of the infants in the study chose the helper toy, giving strong evidence of a genuine preference for the toy with the helping behavior.

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Drawing Conclusions from Statistics

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Learning Objectives

  • Describe the role of random sampling and random assignment in drawing cause-and-effect conclusions

Generalizability

Photo of a diverse group of college-aged students.
Figure 1. Generalizability is an important research consideration: The results of studies with widely representative samples are more likely to generalize to the population. [Image: Barnacles Budget Accommodation]

One limitation to the study mentioned previously about the babies choosing the “helper” toy is that the conclusion only applies to the 16 infants in the study. We don’t know much about how those 16 infants were selected. Suppose we want to select a subset of individuals (a sample) from a much larger group of individuals (the population) in such a way that conclusions from the sample can be generalized to the larger population. This is the question faced by pollsters every day.

Example 1: The General Social Survey (GSS) is a survey on societal trends conducted every other year in the United States. Based on a sample of about 2,000 adult Americans, researchers make claims about what percentage of the U.S. population consider themselves to be “liberal,” what percentage consider themselves “happy,” what percentage feel “rushed” in their daily lives, and many other issues. The key to making these claims about the larger population of all American adults lies in how the sample is selected. The goal is to select a sample that is representative of the population, and a common way to achieve this goal is to select a random sample that gives every member of the population an equal chance of being selected for the sample. In its simplest form, random sampling involves numbering every member of the population and then using a computer to randomly select the subset to be surveyed. Most polls don’t operate exactly like this, but they do use probability-based sampling methods to select individuals from nationally representative panels.

In 2004, the GSS reported that 817 of 977 respondents (or 83.6%) indicated that they always or sometimes feel rushed. This is a clear majority, but we again need to consider variation due to random sampling. Fortunately, we can use the same probability model we did in the previous example to investigate the probable size of this error. (Note, we can use the coin-tossing model when the actual population size is much, much larger than the sample size, as then we can still consider the probability to be the same for every individual in the sample.) This probability model predicts that the sample result will be within 3 percentage points of the population value (roughly 1 over the square root of the sample size, the margin of error). A statistician would conclude, with 95% confidence, that between 80.6% and 86.6% of all adult Americans in 2004 would have responded that they sometimes or always feel rushed.

The key to the margin of error is that when we use a probability sampling method, we can make claims about how often (in the long run, with repeated random sampling) the sample result would fall within a certain distance from the unknown population value by chance (meaning by random sampling variation) alone. Conversely, non-random samples are often suspect to bias, meaning the sampling method systematically over-represents some segments of the population and under-represents others. We also still need to consider other sources of bias, such as individuals not responding honestly. These sources of error are not measured by the margin of error.

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Cause and Effect

In many research studies, the primary question of interest concerns differences between groups. Then the question becomes how were the groups formed (e.g., selecting people who already drink coffee vs. those who don’t). In some studies, the researchers actively form the groups themselves. But then we have a similar question—could any differences we observe in the groups be an artifact of that group-formation process? Or maybe the difference we observe in the groups is so large that we can discount a “fluke” in the group-formation process as a reasonable explanation for what we find?

Example 2: A psychology study investigated whether people tend to display more creativity when they are thinking about intrinsic (internal) or extrinsic (external) motivations (Ramsey & Schafer, 2002, based on a study by Amabile, 1985). The subjects were 47 people with extensive experience with creative writing. Subjects began by answering survey questions about either intrinsic motivations for writing (such as the pleasure of self-expression) or extrinsic motivations (such as public recognition). Then all subjects were instructed to write a haiku, and those poems were evaluated for creativity by a panel of judges. The researchers conjectured beforehand that subjects who were thinking about intrinsic motivations would display more creativity than subjects who were thinking about extrinsic motivations. The creativity scores from the 47 subjects in this study are displayed in Figure 2, where higher scores indicate more creativity.

Image showing a dot for creativity scores, which vary between 5 and 27, and the types of motivation each person was given as a motivator, either extrinsic or intrinsic.
Figure 2. Creativity scores separated by type of motivation.

In this example, the key question is whether the type of motivation affects creativity scores. In particular, do subjects who were asked about intrinsic motivations tend to have higher creativity scores than subjects who were asked about extrinsic motivations?

Figure 2 reveals that both motivation groups saw considerable variability in creativity scores, and these scores have considerable overlap between the groups. In other words, it’s certainly not always the case that those with extrinsic motivations have higher creativity than those with intrinsic motivations, but there may still be a statistical tendency in this direction. (Psychologist Keith Stanovich (2013) refers to people’s difficulties with thinking about such probabilistic tendencies as “the Achilles heel of human cognition.”)

The mean creativity score is 19.88 for the intrinsic group, compared to 15.74 for the extrinsic group, which supports the researchers’ conjecture. Yet comparing only the means of the two groups fails to consider the variability of creativity scores in the groups. We can measure variability with statistics using, for instance, the standard deviation: 5.25 for the extrinsic group and 4.40 for the intrinsic group. The standard deviations tell us that most of the creativity scores are within about 5 points of the mean score in each group. We see that the mean score for the intrinsic group lies within one standard deviation of the mean score for extrinsic group. So, although there is a tendency for the creativity scores to be higher in the intrinsic group, on average, the difference is not extremely large.

We again want to consider possible explanations for this difference. The study only involved individuals with extensive creative writing experience. Although this limits the population to which we can generalize, it does not explain why the mean creativity score was a bit larger for the intrinsic group than for the extrinsic group. Maybe women tend to receive higher creativity scores? Here is where we need to focus on how the individuals were assigned to the motivation groups. If only women were in the intrinsic motivation group and only men in the extrinsic group, then this would present a problem because we wouldn’t know if the intrinsic group did better because of the different type of motivation or because they were women. However, the researchers guarded against such a problem by randomly assigning the individuals to the motivation groups. Like flipping a coin, each individual was just as likely to be assigned to either type of motivation. Why is this helpful? Because this random assignment tends to balance out all the variables related to creativity we can think of, and even those we don’t think of in advance, between the two groups. So we should have a similar male/female split between the two groups; we should have a similar age distribution between the two groups; we should have a similar distribution of educational background between the two groups; and so on. Random assignment should produce groups that are as similar as possible except for the type of motivation, which presumably eliminates all those other variables as possible explanations for the observed tendency for higher scores in the intrinsic group.

But does this always work? No, so by “luck of the draw” the groups may be a little different prior to answering the motivation survey. So then the question is, is it possible that an unlucky random assignment is responsible for the observed difference in creativity scores between the groups? In other words, suppose each individual’s poem was going to get the same creativity score no matter which group they were assigned to, that the type of motivation in no way impacted their score. Then how often would the random-assignment process alone lead to a difference in mean creativity scores as large (or larger) than 19.88 – 15.74 = 4.14 points?

We again want to apply to a probability model to approximate a p-value, but this time the model will be a bit different. Think of writing everyone’s creativity scores on an index card, shuffling up the index cards, and then dealing out 23 to the extrinsic motivation group and 24 to the intrinsic motivation group, and finding the difference in the group means. We (better yet, the computer) can repeat this process over and over to see how often, when the scores don’t change, random assignment leads to a difference in means at least as large as 4.41. Figure 3 shows the results from 1,000 such hypothetical random assignments for these scores.

Standard distribution in a typical bell curve.
Figure 3. Differences in group means under random assignment alone.

Only 2 of the 1,000 simulated random assignments produced a difference in group means of 4.41 or larger. In other words, the approximate p-value is 2/1000 = 0.002. This small p-value indicates that it would be very surprising for the random assignment process alone to produce such a large difference in group means. Therefore, as with Example 2, we have strong evidence that focusing on intrinsic motivations tends to increase creativity scores, as compared to thinking about extrinsic motivations.

Notice that the previous statement implies a cause-and-effect relationship between motivation and creativity score; is such a strong conclusion justified? Yes, because of the random assignment used in the study. That should have balanced out any other variables between the two groups, so now that the small p-value convinces us that the higher mean in the intrinsic group wasn’t just a coincidence, the only reasonable explanation left is the difference in the type of motivation. Can we generalize this conclusion to everyone? Not necessarily—we could cautiously generalize this conclusion to individuals with extensive experience in creative writing similar the individuals in this study, but we would still want to know more about how these individuals were selected to participate.

Conclusion

Close-up photo of mathematical equations.
Figure 4. Researchers employ the scientific method that involves a great deal of statistical thinking: generate a hypothesis –> design a study to test that hypothesis –> conduct the study –> analyze the data –> report the results. [Image: widdowquinn]

Statistical thinking involves the careful design of a study to collect meaningful data to answer a focused research question, detailed analysis of patterns in the data, and drawing conclusions that go beyond the observed data. Random sampling is paramount to generalizing results from our sample to a larger population, and random assignment is key to drawing cause-and-effect conclusions. With both kinds of randomness, probability models help us assess how much random variation we can expect in our results, in order to determine whether our results could happen by chance alone and to estimate a margin of error.

So where does this leave us with regard to the coffee study mentioned previously (the Freedman, Park, Abnet, Hollenbeck, & Sinha, 2012 found that men who drank at least six cups of coffee a day had a 10% lower chance of dying (women 15% lower) than those who drank none)? We can answer many of the questions:

This study needs to be reviewed in the larger context of similar studies and consistency of results across studies, with the constant caution that this was not a randomized experiment. Whereas a statistical analysis can still “adjust” for other potential confounding variables, we are not yet convinced that researchers have identified them all or completely isolated why this decrease in death risk is evident. Researchers can now take the findings of this study and develop more focused studies that address new questions.

Learn More

Explore these outside resources to learn more about applied statistics:

Think It Over

  • Find a recent research article in your field and answer the following: What was the primary research question? How were individuals selected to participate in the study? Were summary results provided? How strong is the evidence presented in favor or against the research question? Was random assignment used? Summarize the main conclusions from the study, addressing the issues of statistical significance, statistical confidence, generalizability, and cause and effect. Do you agree with the conclusions drawn from this study, based on the study design and the results presented?
  • Is it reasonable to use a random sample of 1,000 individuals to draw conclusions about all U.S. adults? Explain why or why not.

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How to Read Research

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Learning Objectives

  • Describe the basic structure of a psychological research article

In this course and throughout your academic career, you’ll be reading journal articles (meaning they were published by experts in a peer-reviewed journal) and reports that explain psychological research. It’s important to understand the format of these articles so that you can read them strategically and understand the information presented. Scientific articles vary in content or structure, depending on the type of journal to which they will be submitted. Psychological articles and many papers in the social sciences follow the writing guidelines and format dictated by the American Psychological Association (APA). In general, the structure follows: abstract, introduction, methods, results, discussion, and references.

Watch It

Watch this video for an explanation on how to read scholarly articles. Look closely at the example article shared just before the two minute mark.

Thumbnail for the embedded element "What is a Scholarly Article?"

A Vimeo element has been excluded from this version of the text. You can view it online here: https://pressbooks.online.ucf.edu/lumenpsychology/?p=151

Practice identifying these key components in the following experiment: Food-Induced Emotional Resonance Improves Emotion Recognition.

Try It

An interactive or media element has been excluded from this version of the text. You can view it online here:
https://pressbooks.online.ucf.edu/lumenpsychology/?p=151

 

Psych in Real Life: Brain Imaging and Messy Science

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Learning Objectives

  • Describe replication and its importance to psychology

This is a little difficult for a psychologist to ask, but here goes: when you think of a “science” which one of these is more likely to come to mind: physics or psychology?

We suspect you chose “physics” (though we don’t have the data, so maybe not!).

Despite the higher “status” of physics and chemistry in the world of science over psychology, good scientific reasoning is just as important in psychology. Valid logic, careful methodology, strong results, and empirically supported conclusions should be sought after regardless of the topic area.

We would like to you to exercise your scientific reasoning using the example below. Read the passage “Watching TV is Related to Math Ability” and answer a few questions afterwards.

Watching TV is Related to Math Ability

Television is often criticized for having a negative impact on our youth. Everything from aggressive behavior to obesity in children seems to be blamed on their television viewing habits. On the other hand, TV also provides us with much of our news and entertainment, and has become a major source of education for children, with shows like Sesame Street teaching children to count and say the alphabet.

Recently, researchers Ian McAtee and Leo Geraci at Harvard University did some research to examine if TV watching might have beneficial effects on cognition. The approach was fairly simple. Children between the ages of 12-14 were either asked to watch a television sitcom or do arithmetic problems, and while they were doing these activities, images of their brains were recorded using fMRI (functional magnetic resonance imaging). This technique measures the flow of blood to specific parts of the brain during performance, allowing scientists to create images of the areas that are activated during cognition.

Two images of brain fMRI scans. The top image shows red areas of activation in three different regions on the back of the head, and he bottom scan shows activation in two similar areas. A bar showing the intensity of the activation from red (2) to yellow (10) is shown next to the brain scans.Results revealed that similar areas of the parietal lobes were active during TV watching (the red area of the brain image on the top) and during arithmetic solving (the red area of the brain image on the bottom). This area of the brain has been implicated in other research as being important for abstract thought, suggesting that both TV watching and arithmetic processing may have beneficial effects on cognition. “We were somewhat surprised that TV watching would activate brain areas involved in higher-order thought processes because TV watching is typically considered a passive activity,” said McAtee. Added Geraci, “The next step is to see what specific content on the TV show led to the pattern of activation that mimicked math performance, so we need to better understand that aspect of the data. We also need to compare TV watching to other types of cognitive skills, like reading comprehension and writing.” Although this is only the beginning to this type of research, these findings certainly question the accepted wisdom that the “idiot box” is harmful to children’s cognitive functioning.

Try It

Please rate whether you agree or disagree with the following statements about the article. There are no incorrect answers.

The article was well written.

  • strongly disagree
  • disagree
  • agree
  • strongly agree

The title, “Watching TV is Related to Math Ability” was a good description of the results.

  • strongly disagree
  • disagree
  • agree
  • strongly agree

The scientific argument in the article made sense.

  • strongly disagree
  • disagree
  • agree
  • strongly agree

It is pretty surprising to learn that watching television can improve your math ability, and the fact that we can identify the area in the brain that produces this relationship shows how far psychology has progressed as a science.

Or maybe not.

The article you just read and rated was not an account of real research. Ian McAtee and Leo Geraci are not real people and the study discussed was never conducted (as far as we know). The article was written by psychologists David McCabe and Alan Castel for a study they published in 2008.David P. McCabe & Alan D. Castel (2008). Seeing is believing: The effect of brain images on judgments of scientific reasoning. Cognition, 107, 343-352. They asked people to do exactly what you just did: read this article and two others and rate them.

McCabe and Castel wondered if people’s biases about science influence the way they judge the information they read. In other words, if what you are reading looks more scientific, do you assume it is better science?

In recent years, neuroscience has impressed a lot of people as “real science,” when compared to the “soft science” of psychology. Did you notice the pictures of the brain next to the article that you just read? Do you think that picture had any influence on your evaluation of the scientific quality of the article? The brain pictures actually added no new information that was not already in the article itself other than showing you exactly where in the brain the relevant part of the parietal lobe is located. The red marks are in the same locations in both brain pictures, but we already knew that “Results revealed that similar areas in the parietal lobes were active during TV watching…and during arithmetic solving.”

McCabe & Castel Experiment

McCabe and Castel wrote three brief (fake) scientific articles that appeared to be typical reports like those you might find in a textbook or news source, all with brain activity as part of the story. In addition to the one you read (“Watching TV is related to math ability “) others had these titles: “Meditation enhances creative thought” and “Playing video games benefits attention.”

All of the articles had flawed scientific reasoning. In the “Watching TV is Related to Math Ability” article that you read, the only “result” that is reported is that a particular brain area (a part of the parietal lobe) is active when a person is watching TV and when he or she is working on math. The highlighted part of the next sentence is where the article goes too far: “This area of the brain has been implicated in other research as being important for abstract thought, suggesting that both tv watching and arithmetic processing may have beneficial effects on cognition.”

The fact that the same area of the brain is active for two different activities does not “suggest” that either one is beneficial or that there is any interesting similarity in mental or brain activity between the processes. The final part of the article goes on and on about how this supposedly surprising finding is intriguing and deserves extensive exploration.

Try It

An interactive or media element has been excluded from this version of the text. You can view it online here:
https://pressbooks.online.ucf.edu/lumenpsychology/?p=153

The researchers asked 156 college students to read the three articles and rate them for how much they made sense scientifically, as well as rating the quality of the writing and the accuracy of the title.

Everybody read exactly the same articles, but the picture that accompanied the article differed according to create three experimental conditions. For the article in the brain image condition, subjects saw one of the following brain images to the side of the article:

3 different images. The first is the brain activation fMRI showing activity in the brain, the other shows an overhead fMRI of activation and a statement that says "meditation enhances creative thought." The last shows another brain scan saying "playing video games enhances attention."
Figure 1. Subjects in the experimental condition were shown ONE of the applicable brain images with each article they read.

Graphs are a common and effective way to display results in science and other areas, but most people are so used to seeing graphs that (according to McCabe and Castel) people should be less impressed by them than by brain images. The figures below show the graphs that accompanied the three articles for the bar graph condition. The results shown in the graphs were made up by the experimenters, but what they show is consistent with the information in the article.

3 bar graphs. The first on "watching tv is related to math ability" shows two bars of about the same height showing parietal lobe activation. The second says "meditation enhances creative thought" and shows similar types of activation in the occipital, temporal, parietal, and frontal lobes. The last on "playing video games enhances attention" shows more activation in the parietal lobe in gaming experts over novices.
Figure 2. Participants in the bar graph condition were shown ONE of the bar graphs with each article they read.

Finally, in the control condition, the article was presented without any accompanying figure or picture. The control condition tells us how the subjects rate the articles without any extraneous, but potentially biasing, illustrations.

Procedure

Each participant read all three articles: one with a brain image, one with a bar graph, and one without any illustration (the control condition). Across all the participants, each article was presented approximately the same number of times in each condition, and the order in which the articles were presented was randomized.

Ratings

Immediately after reading each article, the participants rated their agreement with three statements: (a) The article was well written, (b) The title was a good description of the results, and (c) The scientific reasoning in the article made sense. Each rating was on a 4-point scale: (score=1) strongly disagree, (score=2) disagree, (score=3) agree, and (score=4) strongly agree. Remember that the written part of the articles was exactly the same in all three conditions, so the ratings should have been the same if people were not using the illustrations to influence their conclusions.

Before going on, let’s make sure you know the basic design of this experiment. In other words, can you identify the critical variables used in the study according to their function?

Try It

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Results for (a) Accuracy of the Title and (b) Quality of the Writing

The first two questions for the participants were about (a) the accuracy of the title and (b) the quality of the writing. These questions were included to assure that the participants had read the articles closely. The experimenters expected that there would be no differences in the ratings for the three conditions for these questions. For the question about the title, their prediction was correct. Subjects gave about the same rating to the titles in all three conditions, agreeing that it was accurate.

For question (b) about the quality of the writing, the experimenters found that the two conditions with illustrations (the brain images and the bar graphs) were rated higher than the control condition. Apparently just the presence of an illustration made the writing seem better. This result was not predicted.

Results for (c) Scientific Reasoning Assessment

The main hypothesis behind this study was that subjects would rate the quality of the scientific reasoning in the article higher when it was accompanied by a brain image than when there was a bar graph or there was no illustration at all. If the ratings differed among conditions, then the illustrations—which added nothing substantial that was not in the writing—had to be the cause.

Try It

Use the graph below to show your predicted results of the experiment. Move the bars to the point where you think people generally agreed or disagreed with the statement that “the scientific reasoning in the article made sense.” Higher bars mean that the person believes the reasoning in the article is better, and a lower bar means that they judge the reasoning as worse. Click on “Show Results” when you are done to compare your prediction with the actual results.

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Show Results

RESULTS: The results supported the experimenters’ prediction. The scientific reasoning for the Brain Image condition was rated as significantly higher than for either other condition. There was no significant difference between the Bar Graph condition and the Control condition. Here is a graph of the results:Bar graph of the experiment's results. With the brain image 2.9 people agreed, with a bar graph 2.7 agreed, and 2.7 agreed in the control condition.

Conclusions

McCabe and Castel conducted two more experiments, changing the stories, the images, and the wording of the questions in each. Across the three experiments, they tested almost 400 college students and their results were consistent: participants rated the quality of scientific reasoning higher when the writing was accompanied by a brain image than in other conditions.

The implications of this study go beyond brain images. The deeper idea is that any information that symbolizes something we believe is important can influence our thinking, sometimes making us less thoughtful than we might otherwise be. This other information could be a brain image or some statistical jargon that sounds impressive or a mathematical formula that we don’t understand or a statement that the author teaches at Harvard University rather than Littletown State College.

In a study also published in 2008, Deena Weisberg and her colleagues at Yale University conducted a study similar to the one you just read.Deena Skolnick Weisberg, Frank C. Keil, Joshua Goodstein, Elizabeth Rawson, & Jeremy R. Gray (2008). The seductive allure of neuroscience explanations. Journal of Cognitive Neuroscience, 20(3), 470-477 Weisberg had people read brief descriptions of psychological phenomena (involving memory, attention, reasoning, emotion, and other similar topics). They rated the scientific quality of the explanations. Instead of images, Weisberg had some explanations that included entirely superfluous and useless brain information (e.g., “people feel strong emotion because the amygdala processes emotion”) or no such brain information. Weisberg found that a good explanation was rated as even better when it included a brain reference (which was completely irrelevant). When the explanation was flawed, students were fairly good at catching the reasoning problems UNLESS the explanation contained the irrelevant brain reference. In that case, the students rated the flawed explanations as being good. Weinstein and her colleague call the problem “the seductive allure of neuroscience explanations.”

Does it Replicate? The Messy World of Real Science

A few years after the McCabe and Castel study was published, some psychologistsRobert B. Michael, Eryn J. Newman, Matti Vuorre, Geoff Cumming, and Maryanne Garry (2013). On the (non)persuasive power of a brain image. Psychonomic Bulletin & Review, 20(4), 720-725. at the University of Victoria in New Zealand, led by Robert Michael, were intrigued by the results and they were impressed by how frequently the paper had been cited by other researchers (about 40 citations per year between 2008 and 2012—a reasonably strong citation record). They wanted to explore the brain image effect, so they started by simply replicating the original study.They actually tried to replicate Experiment 3 in the McCabe and Castel study. You read Experiment 1. These two experiments were similar and supported the same conclusions, but Dr. Michael and his colleagues preferred Experiment 3 for some technical reasons.

In their first attempt at replication, the researchers recruited and tested people using an online site called Mechanical Turk. With 197 participants, they found no hint of an effect of the brain image on people’s judgments about the validity of the conclusions of the article they read. In a second replication study, they tested students from their university and again found no statistically significant effect. In this second attempt, the results were in the predicted direction (the presence of a brain image was associated with higher ratings), but the differences were not strong enough to be persuasive. They tried slight variations on instructions and people recruited, but across 10 different replication studies, only one produced a statistically significant effect.

Try It

An interactive or media element has been excluded from this version of the text. You can view it online here:
https://pressbooks.online.ucf.edu/lumenpsychology/?p=153

So, did Dr. Michael and his colleagues accuse McCabe and Castel of doing something wrong? Did they tear apart the experiments we described earlier and show that they were poorly planned, incorrectly analyzed, or interpreted in a deceptive way?

Not at all.

It is instructive to see how professional scientists approached the problem of failing to replicate a study. Here is a quick review of the approach taken by the researchers who did not replicate the McCabe and Castel study:

Do images really directly affect people’s judgments of the quality of scientific thinking? Maybe yes. Maybe no. That’s still an open question.

The “Replication Crisis”

In recent years, there has been increased effort in the sciences (psychology, medicine, economics, etc.) to redo previous experiments to test their reliability. The findings have been disappointing at times.

The Reproducibility Project has attempted to replicate 100 studies within the field of psychology that were published with statistically significant results; they found that many of these results did not replicate well. Some did not reach statistical significance when replicated. Others reached statistical significance, but with much weaker effects than in the original study.

How could this happen?

  • Chance. Psychologist use statistics to confirm that their results did not occur simply because of chance. Within psychology, the most common standard for p-values is “p < .05”. This p-value means that there is less than a 5% probability that the results of an experiment happened just by random chance, and a 95% probability that the results were statistically significant. Even though a published study may reveal statistically significant results, there is still a possibility that those results were random.
  • Publication bias. Psychology research journals are far more likely to publish studies that find statistically significant results than they are studies that fail to find statistically significant results. What this means is that studies that yield results that are not statistically significant are very unlikely to get published. Let’s say that twenty researchers are all studying the same phenomenon. Out of the twenty, one gets statistically significant results, while the other nineteen all get non-significant results. The statistically significant result was likely just a result of randomness, but because of publication bias, that one study’s results are far more likely to be published than are the results of the other nineteen.

Note that this “replication crisis” itself does not mean that the original studies were bad, fraudulent, or even wrong. What it means, at its core, is that replication found results that were different from the results of the original studies. These results were sufficiently different that we might no longer be secure in our knowledge of what those results mean. Further replication and testing in other directions might give us a better understanding of why the results were different, but that too will require time and resources.

One Final Note

When we wrote to Dr. Alan Castel for permission to use his stimuli in this article, he not only consented, but he also sent us his data and copies of all of his stimuli. He sent copies of research by a variety of people, some research that has supported his work with David McCabe and some that has not. He even included a copy of the 10-experiment paper that you just read about, the one that failed to replicate the McCabe and Castel study.

The goal is to find the truth, not to insist that everything you publish is the last word on the topic. In fact, if it is the last word, then you are probably studying something so boring that no one else really cares.

Scientists disagree with one another all the time. But the disagreements are (usually) not personal. The evidence is not always neat and tidy, and the best interpretation of complex results is seldom obvious. At its best, it is possible for scientists to disagree passionately about theory and evidence, and later to relax over a cool drink, laugh and talk about friends or sports or life.

Putting It Together: Psychological Research

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Learning Objectives

In this module, you learned to

  • define and apply the scientific method to psychology
  • describe the strengths and weaknesses of descriptive, experimental, and correlational research
  • define the basic elements of a statistical investigation

Psychologists use the scientific method to examine human behavior and mental processes. Some of the methods you learned about include descriptive, experimental, and correlational research designs.

Watch It

Watch the CrashCourse video to review the material you learned, then read through the following examples and see if you can come up with your own design for each type of study.

An interactive or media element has been excluded from this version of the text. You can view it online here: https://pressbooks.online.ucf.edu/lumenpsychology/?p=155

You can view the transcript for “Psychological Research: Crash Course Psychology #2” here (opens in new window).

Case Study: a detailed analysis of a particular person, group, business, event, etc. This approach is commonly used to to learn more about rare examples with the goal of describing that particular thing.

Naturalistic Observation: a researcher unobtrusively collects information without the participant’s awareness.

Survey: participants are asked to provide information or responses to questions on a survey or structure assessment.

Archival research: researchers examine data that has already been collected for other purposes.
  • Anderson (1987) tried to find the relationship between uncomfortably hot temperatures and aggressive behavior, which was then looked at with two studies done on violent and nonviolent crime. Based on previous research that had been done by Anderson and Anderson (1984), it was predicted that violent crimes would be more prevalent during the hotter time of year and the years in which it was hotter weather in general. The study confirmed this prediction.

Longitudinal Study: researchers recruit a sample of participants and track them for an extended period of time.

  • In a study of a representative sample of 856 children Eron and his colleagues (1972) found that a boy’s exposure to media violence at age eight was significantly related to his aggressive behavior ten years later, after he graduated from high school.

Cross-Sectional Study: researchers gather participants from different groups (commonly different ages) and look for differences between the groups.

  • In 1996, Russell surveyed people of varying age groups and found that people in their 20s tend to report being more lonely than people in their 70s.

Correlational Design: two different variables are measured to determine whether there is a relationship between them.

  • Thornhill et al. (2003) had people rate how physically attractive they found other people to be. They then had them separately smell t-shirts those people had worn (without knowing which clothes belonged to whom) and rate how good or bad their body oder was. They found that the more attractive someone was the more pleasant their body order was rated to be.
Experiment: researchers create a controlled environment in which they can carefully manipulate at least one variable to test its effect on another. The key here is that the researchers can cause a change in one variable.
  • Clinical psychologists can test a new pharmaceutical treatment for depression by giving some patients the new pill and others an already-tested one to see which is the more effective treatment.

Discussion: Research in Psychology

65

Analyzing Research

Step 1: Visit the Public Library of Science (PLOS One) website (a peer-reviewed journal that freely publishes research articles with open licenses). Do a search for an article that interests you, then answer the following:

  1. What is the hyperlink to the study you chose?
  2. What is the title of the study, and who conducted the research?
  3. Describe the study in a few sentences in your own words.
  4. Identify and describe either the basic assumption of the researchers, or if it was an experiment, the hypothesis. Why were they conducting this research?
  5. How was the study performed? What methods were used?
  6. What were the results and conclusions of this study?
  7. What questions do you still have after reading about this study? For example, if you were to conduct another study based off of this study, what questions would you ask and what would you still want to find out?

Step 2: Respond to at least TWO other posts in responses in a paragraph with at least 75 words. Your comments should facilitate a discussion and can highlight your own thoughts about the study.

Domain 1: Biological Psychology

VI

Biopsychology

VII

Introduction to Neural Communication

66

What you’ll learn to do: identify the basic structures of a neuron, the function of each structure, and how messages travel through the neuron

Cortical neuron stained with antibody to neurofilament subunit NF-L in green. In red are neuronal stem cells stained with antibody to alpha-internexin. Image created using antibodies from EnCor Biotechnology Inc.
Figure 1. Neuron in tissue culture.

Ever wonder how your brain actually works? What exactly is going on inside of your small, wrinkly mass while you read this text? In this section, you’ll learn about the basics of neural communication in the brain, which is the brain’s way of sending messages to and from different regions in order to relay critical information about your body and its surroundings.

Glia and neurons are the two cell types that make up the nervous system. While glia generally play supporting roles, the communication between neurons is fundamental to all of the functions associated with the nervous system. Neuronal communication is made possible by the neuron’s specialized structures, like the soma, dendrites, axons, terminal buttons, and synaptic vesicles.

Neuronal communication is an electrochemical event. The dendrites contain receptors for neurotransmitters released by nearby neurons. If the signals received from other neurons are sufficiently strong, an action potential will travel down the length of the axon to the terminal buttons, resulting in the release of neurotransmitters into the synapse.

Different neurotransmitters are associated with different functions. Often, psychological disorders involve imbalances in a given neurotransmitter system. Therefore, psychotropic drugs are prescribed in an attempt to bring the neurotransmitters back into balance. Drugs can act either as agonists or as antagonists for a given neurotransmitter system.

Learning Objectives

  • Explain the role and function of the basic structures of a neuron
  • Describe how neurons communicate with each other
  • Explain how drugs act as agonists or antagonists for a given neurotransmitter system

Neurons

67

Learning Objectives

  • Explain the role and function of the basic structures of a neuron

Psychologists striving to understand the human mind may study the nervous system. Learning how the cells and organs (like the brain) function, help us understand the biological basis behind human psychology. The nervous system is composed of two basic cell types: glial cells (also known as glia) and neurons. Glial cells, which outnumber neurons ten to one, are traditionally thought to play a supportive role to neurons, both physically and metabolically. Glial cells provide scaffolding on which the nervous system is built, help neurons line up closely with each other to allow neuronal communication, provide insulation to neurons, transport nutrients and waste products, and mediate immune responses. Neurons, on the other hand, serve as interconnected information processors that are essential for all of the tasks of the nervous system. This section briefly describes the structure and function of neurons.

Neuron Structure

Neurons are the central building blocks of the nervous system, 100 billion strong at birth. Like all cells, neurons consist of several different parts, each serving a specialized function. A neuron’s outer surface is made up of a semipermeable membrane. This membrane allows smaller molecules and molecules without an electrical charge to pass through it, while stopping larger or highly charged molecules.

An illustration shows a neuron with labeled parts for the cell membrane, dendrite, cell body, axon, and terminal buttons. A myelin sheath covers part of the neuron.
Figure 1. This illustration shows a prototypical neuron, which is being myelinated.

The nucleus of the neuron is located in the soma, or cell body. The soma has branching extensions known as dendrites. The neuron is a small information processor, and dendrites serve as input sites where signals are received from other neurons. These signals are transmitted electrically across the soma and down a major extension from the soma known as the axon, which ends at multiple terminal buttons. The terminal buttons contain synaptic vesicles that house neurotransmitters, the chemical messengers of the nervous system.

Axons range in length from a fraction of an inch to several feet. In some axons, glial cells form a fatty substance known as the myelin sheath, which coats the axon and acts as an insulator, increasing the speed at which the signal travels. The myelin sheath is crucial for the normal operation of the neurons within the nervous system: the loss of the insulation it provides can be detrimental to normal function. To understand how this works, let’s consider an example. Multiple sclerosis (MS), an autoimmune disorder, involves a large-scale loss of the myelin sheath on axons throughout the nervous system. The resulting interference in the electrical signal prevents the quick transmittal of information by neurons and can lead to a number of symptoms, such as dizziness, fatigue, loss of motor control, and sexual dysfunction. While some treatments may help to modify the course of the disease and manage certain symptoms, there is currently no known cure for multiple sclerosis.

In healthy individuals, the neuronal signal moves rapidly down the axon to the terminal buttons, where synaptic vesicles release neurotransmitters into the synapse. The synapse is a very small space between two neurons and is an important site where communication between neurons occurs. Once neurotransmitters are released into the synapse, they travel across the small space and bind with corresponding receptors on the dendrite of an adjacent neuron. Receptors, proteins on the cell surface where neurotransmitters attach, vary in shape, with different shapes “matching” different neurotransmitters.

Watch It

This video shows the structure and physiology of a neuron.

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You can view the transcript for “2-Minute Neuroscience: The Neuron” here (opens in new window).

How does a neurotransmitter “know” which receptor to bind to? The neurotransmitter and the receptor have what is referred to as a lock-and-key relationship—specific neurotransmitters fit specific receptors similar to how a key fits a lock. The neurotransmitter binds to any receptor that it fits.

Image (a) shows the synaptic space between two neurons, with neurotransmitters being released into the synapse and attaching to receptors. Image (b) is a micrograph showing a spherical terminal button with part of the exterior removed, revealing a solid interior of small round parts.
Figure 2. (a) The synapse is the space between the terminal button of one neuron and the dendrite of another neuron. (b) In this pseudo-colored image from a scanning electron microscope, a terminal button (green) has been opened to reveal the synaptic vesicles (orange and blue) inside. Each vesicle contains about 10,000 neurotransmitter molecules. (credit b: modification of work by Tina Carvalho, NIH-NIGMS; scale-bar data from Matt Russell)

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How Neurons Communicate

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Learning Objectives

  • Describe how neurons communicate with each other
  • Explain how drugs act as agonists or antagonists for a given neurotransmitter system

Now that we have learned about the basic structures of the neuron and the role that these structures play in neuronal communication, let’s take a closer look at the signal itself—how it moves through the neuron and then jumps to the next neuron, where the process is repeated.

We begin at the neuronal membrane. The neuron exists in a fluid environment—it is surrounded by extracellular fluid and contains intracellular fluid (i.e., cytoplasm). The neuronal membrane keeps these two fluids separate—a critical role because the electrical signal that passes through the neuron depends on the intra- and extracellular fluids being electrically different. This difference in charge across the membrane, called the membrane potential, provides energy for the signal.

The electrical charge of the fluids is caused by charged molecules (ions) dissolved in the fluid. The semipermeable nature of the neuronal membrane somewhat restricts the movement of these charged molecules, and, as a result, some of the charged particles tend to become more concentrated either inside or outside the cell.

Between signals, the neuron membrane’s potential is held in a state of readiness, called the resting potential. Like a rubber band stretched out and waiting to spring into action, ions line up on either side of the cell membrane, ready to rush across the membrane when the neuron goes active and the membrane opens its gates (i.e., a sodium-potassium pump that allows movement of ions across the membrane). Ions in high-concentration areas are ready to move to low-concentration areas, and positive ions are ready to move to areas with a negative charge.

In the resting state, sodium (Na+) is at higher concentrations outside the cell, so it will tend to move into the cell. Potassium (K+), on the other hand, is more concentrated inside the cell, and will tend to move out of the cell (Figure 1). In addition, the inside of the cell is slightly negatively charged compared to the outside. This provides an additional force on sodium, causing it to move into the cell.

A close-up illustration depicts the difference in charges across the cell membrane, and shows how Na+ and K+ cells concentrate more closely near the membrane.
Figure 1. At resting potential, Na+ (blue pentagons) is more highly concentrated outside the cell in the extracellular fluid (shown in blue), whereas K+ (purple squares) is more highly concentrated near the membrane in the cytoplasm or intracellular fluid. Other molecules, such as chloride ions (yellow circles) and negatively charged proteins (brown squares), help contribute to a positive net charge in the extracellular fluid and a negative net charge in the intracellular fluid.

From this resting potential state, the neuron receives a signal and its state changes abruptly (Figure 2). When a neuron receives signals at the dendrites—due to neurotransmitters from an adjacent neuron binding to its receptors—small pores, or gates, open on the neuronal membrane, allowing Na+ ions, propelled by both charge and concentration differences, to move into the cell. With this influx of positive ions, the internal charge of the cell becomes more positive. If that charge reaches a certain level, called the threshold of excitation, the neuron becomes active and the action potential begins. This process of when the cell’s charge becomes positive, or less negative, is called depolarization.

Many additional pores open, causing a massive influx of Na+ ions and a huge positive spike in the membrane potential, the peak action potential. At the peak of the spike, the sodium gates close and the potassium gates open. As positively charged potassium ions leave, the cell quickly begins repolarization. At first, it hyperpolarizes, becoming slightly more negative than the resting potential, and then it levels off, returning to the resting potential.

A graph shows the increase, peak, and decrease in membrane potential. The millivolts through the phases are approximately -70mV at resting potential, -55mV at threshold of excitation, 30mV at peak action potential, 5mV at repolarization, and -80mV at hyperpolarization.
Figure 2. During the action potential, the electrical charge across the membrane changes dramatically.

This positive spike constitutes the action potential: the electrical signal that typically moves from the cell body down the axon to the axon terminals. The electrical signal moves down the axon like a wave; at each point, some of the sodium ions that enter the cell diffuse to the next section of the axon, raising the charge past the threshold of excitation and triggering a new influx of sodium ions. The action potential moves all the way down the axon to the terminal buttons.

Watch It

The process of neural communication is explained in the following video.

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The action potential is an all-or-none phenomenon. In simple terms, this means that an incoming signal from another neuron is either sufficient or insufficient to reach the threshold of excitation. There is no in-between, and there is no turning off an action potential once it starts. Think of it like sending an email or a text message. You can think about sending it all you want, but the message is not sent until you hit the send button. Furthermore, once you send the message, there is no stopping it.

Because it is all or none, the action potential is recreated, or propagated, at its full strength at every point along the axon. Much like the lit fuse of a firecracker, it does not fade away as it travels down the axon. It is this all-or-none property that explains the fact that your brain perceives an injury to a distant body part like your toe as equally painful as one to your nose.

As noted earlier, when the action potential arrives at the terminal button, the synaptic vesicles release their neurotransmitters into the synapse. The neurotransmitters travel across the synapse and bind to receptors on the dendrites of the adjacent neuron, and the process repeats itself in the new neuron (assuming the signal is sufficiently strong to trigger an action potential). Once the signal is delivered, excess neurotransmitters in the synapse drift away, are broken down into inactive fragments, or are reabsorbed in a process known as reuptake. Reuptake involves the neurotransmitter being pumped back into the neuron that released it, in order to clear the synapse (Figure 3). Clearing the synapse serves both to provide a clear “on” and “off” state between signals and to regulate the production of neurotransmitter (full synaptic vesicles provide signals that no additional neurotransmitters need to be produced).

The synaptic space between two neurons is shown. Some neurotransmitters that have been released into the synapse are attaching to receptors while others undergo reuptake into the axon terminal.
Figure 3. Reuptake involves moving a neurotransmitter from the synapse back into the axon terminal from which it was released.

Neuronal communication is often referred to as an electrochemical event. The movement of the action potential down the length of the axon is an electrical event, and movement of the neurotransmitter across the synaptic space represents the chemical portion of the process.

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Watch It

Watch the following video to see how neurons communicate within the body.

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Neurotransmitters and Drugs

There are several different types of neurotransmitters released by different neurons, and we can speak in broad terms about the kinds of functions associated with different neurotransmitters (Table 1). Much of what psychologists know about the functions of neurotransmitters comes from research on the effects of drugs in psychological disorders. Psychologists who take a biological perspective and focus on the physiological causes of behavior assert that psychological disorders like depression and schizophrenia are associated with imbalances in one or more neurotransmitter systems. In this perspective, psychotropic medications can help improve the symptoms associated with these disorders. Psychotropic medications are drugs that treat psychiatric symptoms by restoring neurotransmitter balance.

Table 1. Major Neurotransmitters and How They Affect Behavior
Neurotransmitter Involved in Potential Effect on Behavior
Acetylcholine Muscle action, memory Increased arousal, enhanced cognition
Beta-endorphin Pain, pleasure Decreased anxiety, decreased tension
Dopamine Mood, sleep, learning Increased pleasure, suppressed appetite
Gamma-aminobutyric acid (GABA) Brain function, sleep Decreased anxiety, decreased tension
Glutamate Memory, learning Increased learning, enhanced memory
Norepinephrine Heart, intestines, alertness Increased arousal, suppressed appetite
Serotonin Mood, sleep Modulated mood, suppressed appetite

Psychoactive drugs can act as agonists or antagonists for a given neurotransmitter system. Agonists are chemicals that mimic a neurotransmitter at the receptor site and, thus, strengthen its effects. An antagonist, on the other hand, blocks or impedes the normal activity of a neurotransmitter at the receptor. Agonist and antagonist drugs are prescribed to correct the specific neurotransmitter imbalances underlying a person’s condition. For example, Parkinson’s disease, a progressive nervous system disorder, is associated with low levels of dopamine. Therefore dopamine agonists, which mimic the effects of dopamine by binding to dopamine receptors, are one treatment strategy.

Certain symptoms of schizophrenia are associated with overactive dopamine neurotransmission. The antipsychotics used to treat these symptoms are antagonists for dopamine—they block dopamine’s effects by binding its receptors without activating them. Thus, they prevent dopamine released by one neuron from signaling information to adjacent neurons.

In contrast to agonists and antagonists, which both operate by binding to receptor sites, reuptake inhibitors prevent unused neurotransmitters from being transported back to the neuron. This leaves more neurotransmitters in the synapse for a longer time, increasing its effects. Depression, which has been consistently linked with reduced serotonin levels, is commonly treated with selective serotonin reuptake inhibitors (SSRIs). By preventing reuptake, SSRIs strengthen the effect of serotonin, giving it more time to interact with serotonin receptors on dendrites. Common SSRIs on the market today include Prozac, Paxil, and Zoloft. The drug LSD is structurally very similar to serotonin, and it affects the same neurons and receptors as serotonin. Psychotropic drugs are not instant solutions for people suffering from psychological disorders. Often, an individual must take a drug for several weeks before seeing improvement, and many psychoactive drugs have significant negative side effects. Furthermore, individuals vary dramatically in how they respond to the drugs. To improve chances for success, it is not uncommon for people receiving pharmacotherapy to undergo psychological and/or behavioral therapies as well. Some research suggests that combining drug therapy with other forms of therapy tends to be more effective than any one treatment alone (for one such example, see March et al., 2007).

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Watch It

Review the process of neural communication in the following CrashCourse psychology video:

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Introduction to The Nervous System and the Endocrine System

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What you’ll learn to do: describe the role of the nervous system and endocrine systems

blausen_0822_spinalcord

In this section, you’ll learn about the basics of the central nervous system, which consists of the brain and spinal cord, as well as the peripheral nervous system. The peripheral nervous system is comprised of the somatic and autonomic nervous systems. The somatic nervous system transmits sensory and motor signals to and from the central nervous system. The autonomic nervous system controls the function of our organs and glands, and can be divided into the sympathetic and parasympathetic divisions. Sympathetic activation prepares us for fight or flight, while parasympathetic activation is associated with normal functioning under relaxed conditions. The endocrine system consists of a series of glands that produce chemical substances known as hormones, which produce widespread effects on the body. Got all that? We’ll review each of these systems in the coming pages.

Learning Objectives

  • Describe the difference between the central and peripheral nervous systems and the somatic and autonomic nervous systems
  • Differentiate between the sympathetic and parasympathetic divisions of the autonomic nervous system
  • Describe the endocrine system and explain its primary responsibilities within the body

Parts of the Nervous System

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Learning Objectives

  • Describe the difference between the central and peripheral nervous systems and the somatic and autonomic nervous systems
  • Differentiate between the sympathetic and parasympathetic divisions of the autonomic nervous system

The nervous system can be divided into two major subdivisions: the central nervous system (CNS) and the peripheral nervous system (PNS), shown in Figure 1. The CNS is comprised of the brain and spinal cord; the PNS connects the CNS to the rest of the body. In this section, we focus on the peripheral nervous system; later, we look at the brain and spinal cord.

Image (a) shows an outline of a human body with the brain and spinal cord illustrated. Image (b) shows an outline of a human body with a network of nerves depicted.
Figure 1. The nervous system is divided into two major parts: (a) the Central Nervous System and (b) the Peripheral Nervous System.

Peripheral Nervous System

The peripheral nervous system is made up of thick bundles of axons, called nerves, carrying messages back and forth between the CNS and the muscles, organs, and senses in the periphery of the body (i.e., everything outside the CNS). The PNS has two major subdivisions: the somatic nervous system and the autonomic nervous system.

The somatic nervous system is associated with activities traditionally thought of as conscious or voluntary. It is involved in the relay of sensory and motor information to and from the CNS; therefore, it consists of motor neurons and sensory neurons. Motor neurons, carrying instructions from the CNS to the muscles, are efferent fibers (efferent means “moving away from”). Sensory neurons, carrying sensory information to the CNS, are afferent fibers (afferent means “moving toward”). Each nerve is basically a two-way superhighway, containing thousands of axons, both efferent and afferent.

The autonomic nervous system controls our internal organs and glands and is generally considered to be outside the realm of voluntary control. It can be further subdivided into the sympathetic and parasympathetic divisions (Figure 2). The sympathetic nervous system is involved in preparing the body for stress-related activities; the parasympathetic nervous system is associated with returning the body to routine, day-to-day operations. The two systems have complementary functions, operating in tandem to maintain the body’s homeostasis. Homeostasis is a state of equilibrium, in which biological conditions (such as body temperature) are maintained at optimal levels.

A diagram of a human body lists the different functions of the sympathetic and parasympathetic nervous system. The parasympathetic system can constrict pupils, stimulate salivation, slow heart rate, constrict bronchi, stimulate digestion, stimulate bile secretion, and cause the bladder to contract. The sympathetic nervous system can dilate pupils, inhibit salivation, increase heart rate, dilate bronchi, inhibit digestion, stimulate the breakdown of glycogen, stimulate secretion of adrenaline and noradrenaline, and inhibit contraction of the bladder.
Figure 2. The sympathetic and parasympathetic divisions of the autonomic nervous system have the opposite effects on various systems.

The sympathetic nervous system is activated when we are faced with stressful or high-arousal situations. The activity of this system was adaptive for our ancestors, increasing their chances of survival. Imagine, for example, that one of our early ancestors, out hunting small game, suddenly disturbs a large bear with her cubs. At that moment, his body undergoes a series of changes—a direct function of sympathetic activation—preparing him to face the threat. His pupils dilate, his heart rate and blood pressure increase, his bladder relaxes, his liver releases glucose, and adrenaline surges into his bloodstream. This constellation of physiological changes, known as the fight or flight response, allows the body access to energy reserves and heightened sensory capacity so that it might fight off a threat or run away to safety.

While it is clear that such a response would be critical for survival for our ancestors, who lived in a world full of real physical threats, many of the high-arousal situations we face in the modern world are more psychological in nature. For example, think about how you feel when you have to stand up and give a presentation in front of a roomful of people, or right before taking a big test. You are in no real physical danger in those situations, and yet you have evolved to respond to any perceived threat with the fight or flight response. This kind of response is not nearly as adaptive in the modern world; in fact, we suffer negative health consequences when faced constantly with psychological threats that we can neither fight nor flee. Recent research suggests that an increase in susceptibility to heart disease (Chandola, Brunner, & Marmot, 2006) and impaired function of the immune system (Glaser & Kiecolt-Glaser, 2005) are among the many negative consequences of persistent and repeated exposure to stressful situations.

Once the threat has been resolved, the parasympathetic nervous system takes over and returns bodily functions to a relaxed state. Our hunter’s heart rate and blood pressure return to normal, his pupils constrict, he regains control of his bladder, and the liver begins to store glucose in the form of glycogen for future use. These processes are associated with activation of the parasympathetic nervous system.

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Think It Over

Hopefully, you do not face real physical threats from potential predators on a daily basis. However, you probably have your fair share of stress. What situations are your most common sources of stress? What can you do to try to minimize the negative consequences of these particular stressors in your life?

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The Endocrine System

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Learning Objectives

  • Describe the endocrine system and explain its primary responsibilities within the body

The endocrine system consists of a series of glands that produce chemical substances known as hormones (Figure 1). Like neurotransmitters, hormones are chemical messengers that must bind to a receptor in order to send their signal. However, unlike neurotransmitters, which are released in close proximity to cells with their receptors, hormones are secreted into the bloodstream and travel throughout the body, affecting any cells that contain receptors for them. Thus, whereas neurotransmitters’ effects are localized, the effects of hormones are widespread. Also, hormones are slower to take effect, and tend to be longer lasting.

A diagram of the human body illustrates the locations of the thymus, several parts within the brain (pineal gland, hypothalamus, thalamus, pituitary gland), several parts within the thyroid (cartilage, thyroid gland, parathyroid glands, trachea), the adrenal glands, pancreas, uterus, ovaries, and testes.
Figure 1. The major glands of the endocrine system are shown.

The study of psychology and the endocrine system is called behavioral endocrinology, which is the scientific study of the interaction between hormones and behavior. This interaction is bidirectional: hormones can influence behavior, and behavior can sometimes influence hormone concentrations. Hormones regulate behaviors such as aggression, mating, and parenting of individuals. Hormones are involved in regulating all sorts of bodily functions, and they are ultimately controlled through interactions between the hypothalamus (in the central nervous system) and the pituitary gland (in the endocrine system). Imbalances in hormones are related to a number of disorders. This section explores some of the major glands that make up the endocrine system and the hormones secreted by these glands.

Major Glands

The pituitary gland descends from the hypothalamus at the base of the brain, and acts in close association with it. The pituitary is often referred to as the “master gland” because its messenger hormones control all the other glands in the endocrine system, although it mostly carries out instructions from the hypothalamus. In addition to messenger hormones, the pituitary also secretes growth hormone, endorphins for pain relief, and a number of key hormones that regulate fluid levels in the body.

Located in the neck, the thyroid gland releases hormones that regulate growth, metabolism, and appetite. In hyperthyroidism, or Grave’s disease, the thyroid secretes too much of the hormone thyroxine, causing agitation, bulging eyes, and weight loss. In hypothyroidism, reduced hormone levels cause sufferers to experience tiredness, and they often complain of feeling cold. Fortunately, thyroid disorders are often treatable with medications that help reestablish a balance in the hormones secreted by the thyroid.

The adrenal glands sit atop our kidneys and secrete hormones involved in the stress response, such as epinephrine (adrenaline) and norepinephrine (noradrenaline). The pancreas is an internal organ that secretes hormones that regulate blood sugar levels: insulin and glucagon. These pancreatic hormones are essential for maintaining stable levels of blood sugar throughout the day by lowering blood glucose levels (insulin) or raising them (glucagon). People who suffer from diabetes do not produce enough insulin; therefore, they must take medications that stimulate or replace insulin production, and they must closely control the amount of sugars and carbohydrates they consume.

The gonads secrete sexual hormones, which are important in reproduction, and mediate both sexual motivation and behavior. The female gonads are the ovaries; the male gonads are the testis. Ovaries secrete estrogens and progesterone, and the testes secrete androgens, such as testosterone.

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Dig Deeper: Athletes and Anabolic Steroids

Although it is against most laws to do so, many professional athletes and body builders use anabolic steroid drugs to improve their athletic performance and physique. Anabolic steroid drugs mimic the effects of the body’s own steroid hormones, like testosterone and its derivatives. These drugs have the potential to provide a competitive edge by increasing muscle mass, strength, and endurance, although not all users may experience these results. Moreover, the use of performance-enhancing drugs (PEDs) does not come without risks. Anabolic steroid use has been linked with a wide variety of potentially negative outcomes, ranging in severity from largely cosmetic (acne) to life-threatening (heart attack). Furthermore, the use of these substances can result in profound changes in mood and can increase aggressive behavior (National Institute on Drug Abuse, 2001).

Baseball player Alex Rodriguez (A-Rod) has been at the center of a media storm regarding his use of illegal PEDs. Rodriguez’s performance on the field was unparalleled while using the drugs; his success played a large role in negotiating a contract that made him the highest-paid player in professional baseball. Although Rodriguez maintains that he had not used PEDs, he was suspended for the entire 2014 regular season and postseason, costing him more than 20 million dollars in earnings (Gaines, 2013). What are your thoughts on athletes and doping? Do you believe the use of PEDs should be banned? Why or why not? What advice would you give an athlete who was considering using PEDs?

Hormones and Behavior

How might behaviors affect hormones? Extensive studies on male zebra finches and their singing (only males finches sing) demonstrate that the hormones testosterone and estradiol affect their singing, but the reciprocal relation also occurs; that is, behavior can affect hormone concentrations. For example, the sight of a territorial intruder may elevate blood testosterone concentrations in resident male birds and thereby stimulate singing or fighting behavior. Similarly, male mice or rhesus monkeys that lose a fight decrease circulating testosterone concentrations for several days or even weeks afterward. Comparable results have also been reported in humans. Testosterone concentrations are affected not only in humans involved in physical combat, but also in those involved in simulated battles. For example, testosterone concentrations were elevated in winners and reduced in losers of regional chess tournaments.

People do not have to be directly involved in a contest to have their hormones affected by the outcome of the contest. Male fans of both the Brazilian and Italian teams were recruited to provide saliva samples to be assayed for testosterone before and after the final game of the World Cup soccer match in 1994. Brazil and Italy were tied going into the final game, but Brazil won on a penalty kick at the last possible moment. The Brazilian fans were elated and the Italian fans were crestfallen. When the samples were assayed, 11 of 12 Brazilian fans who were sampled had increased testosterone concentrations, and 9 of 9 Italian fans had decreased testosterone concentrations, compared with pre-game baseline values (Dabbs, 2000).

In some cases, hormones can be affected by anticipation of behavior. For example, testosterone concentrations also influence sexual motivation and behavior in women. In one study, the interaction between sexual intercourse and testosterone was compared with other activities (cuddling or exercise) in women (van Anders, Hamilton, Schmidt, & Watson, 2007). On three separate occasions, women provided a pre-activity, post-activity, and next-morning saliva sample. After analysis, the women’s testosterone was determined to be elevated prior to intercourse as compared to other times. Thus, an anticipatory relationship exists between sexual behavior and testosterone. Testosterone values were higher post-intercourse compared to exercise, suggesting that engaging in sexual behavior may also influence hormone concentrations in women.

Link to Learning

Learn more about endocrinology from The Noba Psychology article, “Hormones and Behavior.”

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Think It Over

Given the negative health consequences associated with the use of anabolic steroids, what kinds of considerations might be involved in a person’s decision to use them?

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Introduction to the Parts of the Brain

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What you’ll learn to do: identify and describe the parts of the brain

Principal fissures and lobes of the cerebrum viewed laterally.

In this section, you’ll learn about the specific parts of the brain and their roles and functions. While this is not an anatomy class, you’ll see how important it is to understand the parts of the brain and what they do so that we can understand mental processes and behavior.

Watch It

Watch this CrashCourse Psychology video for an overview on the brain and the interesting topics we’ll cover:

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You can view the transcript for “Meet Your Master – Getting to Know Your Brain: Crash Course Psychology #4” here (opens in new window).

Learning Objectives

  • Explain the two hemispheres of the brain, lateralization and plasticity
  • Identify the location and function of the lobes of the brain
  • Identify and describe the role of the parts of the limbic system, the midbrain, and hindbrain
  • Describe the types of techniques available to clinicians and researchers to image or scan the brain

Brain Hemispheres

73

Learning Objectives

  • Explain the two hemispheres of the brain, lateralization and plasticity

The central nervous system (CNS), consists of the brain and the spinal cord.

Brain

The brain is a remarkably complex organ comprised of billions of interconnected neurons and glia. It is a bilateral, or two-sided, structure that can be separated into distinct lobes. Each lobe is associated with certain types of functions, but, ultimately, all of the areas of the brain interact with one another to provide the foundation for our thoughts and behaviors.

Spinal Cord

It can be said that the spinal cord is what connects the brain to the outside world. Because of it, the brain can act. The spinal cord is like a relay station, but a very smart one. It not only routes messages to and from the brain, but it also has its own system of automatic processes, called reflexes.

The top of the spinal cord merges with the brain stem, where the basic processes of life are controlled, such as breathing and digestion. In the opposite direction, the spinal cord ends just below the ribs—contrary to what we might expect, it does not extend all the way to the base of the spine.

The spinal cord is functionally organized in 30 segments, corresponding with the vertebrae. Each segment is connected to a specific part of the body through the peripheral nervous system. Nerves branch out from the spine at each vertebra. Sensory nerves bring messages in; motor nerves send messages out to the muscles and organs. Messages travel to and from the brain through every segment.

Some sensory messages are immediately acted on by the spinal cord, without any input from the brain. Withdrawal from heat and knee jerk are two examples. When a sensory message meets certain parameters, the spinal cord initiates an automatic reflex. The signal passes from the sensory nerve to a simple processing center, which initiates a motor command. Seconds are saved, because messages don’t have to go the brain, be processed, and get sent back. In matters of survival, the spinal reflexes allow the body to react extraordinarily fast.

The spinal cord is protected by bony vertebrae and cushioned in cerebrospinal fluid, but injuries still occur. When the spinal cord is damaged in a particular segment, all lower segments are cut off from the brain, causing paralysis. Therefore, the lower on the spine damage is, the fewer functions an injured individual loses.

Two Hemispheres

The surface of the brain, known as the cerebral cortex, is very uneven, characterized by a distinctive pattern of folds or bumps, known as gyri (singular: gyrus), and grooves, known as sulci (singular: sulcus), shown in Figure 1. These gyri and sulci form important landmarks that allow us to separate the brain into functional centers. The most prominent sulcus, known as the longitudinal fissure, is the deep groove that separates the brain into two halves or hemispheres: the left hemisphere and the right hemisphere.

An illustration of the brain’s exterior surface shows the ridges and depressions, and the deep fissure that runs through the center.
Figure 1. The surface of the brain is covered with gyri and sulci. A deep sulcus is called a fissure, such as the longitudinal fissure that divides the brain into left and right hemispheres. (credit: modification of work by Bruce Blaus)

There is evidence of some specialization of function—referred to as lateralization—in each hemisphere, mainly regarding differences in language ability. Beyond that, however, the differences that have been found have been minor (this means that it is a myth that a person is either left-brained dominant or right-brained dominant).Nielsen JA, Zielinski BA, Ferguson MA, Lainhart JE, Anderson JS (2013) An Evaluation of the Left-Brain vs. Right-Brain Hypothesis with Resting State Functional Connectivity Magnetic Resonance Imaging. PLoS ONE 8(8): e71275. https://doi.org/10.1371/journal.pone.0071275 What we do know is that the left hemisphere controls the right half of the body, and the right hemisphere controls the left half of the body.

The two hemispheres are connected by a thick band of neural fibers known as the corpus callosum, consisting of about 200 million axons. The corpus callosum allows the two hemispheres to communicate with each other and allows for information being processed on one side of the brain to be shared with the other side.

Normally, we are not aware of the different roles that our two hemispheres play in day-to-day functions, but there are people who come to know the capabilities and functions of their two hemispheres quite well. In some cases of severe epilepsy, doctors elect to sever the corpus callosum as a means of controlling the spread of seizures (Figure 2). While this is an effective treatment option, it results in individuals who have split brains. After surgery, these split-brain patients show a variety of interesting behaviors. For instance, a split-brain patient is unable to name a picture that is shown in the patient’s left visual field because the information is only available in the largely nonverbal right hemisphere. However, they are able to recreate the picture with their left hand, which is also controlled by the right hemisphere. When the more verbal left hemisphere sees the picture that the hand drew, the patient is able to name it (assuming the left hemisphere can interpret what was drawn by the left hand).

Illustrations (a) and (b) show the corpus callosum’s location in the brain in front and side views. Photograph (c) shows the corpus callosum in a dissected brain.
Figure 2. (a, b) The corpus callosum connects the left and right hemispheres of the brain. (c) A scientist spreads this dissected sheep brain apart to show the corpus callosum between the hemispheres. (credit c: modification of work by Aaron Bornstein)

Much of what we know about the functions of different areas of the brain comes from studying changes in the behavior and ability of individuals who have suffered damage to the brain. For example, researchers study the behavioral changes caused by strokes to learn about the functions of specific brain areas. A stroke, caused by an interruption of blood flow to a region in the brain, causes a loss of brain function in the affected region. The damage can be in a small area, and, if it is, this gives researchers the opportunity to link any resulting behavioral changes to a specific area. The types of deficits displayed after a stroke will be largely dependent on where in the brain the damage occurred.

Consider Theona, an intelligent, self-sufficient woman, who is 62 years old. Recently, she suffered a stroke in the front portion of her right hemisphere. As a result, she has great difficulty moving her left leg. (As you learned earlier, the right hemisphere controls the left side of the body; also, the brain’s main motor centers are located at the front of the head, in the frontal lobe.) Theona has also experienced behavioral changes. For example, while in the produce section of the grocery store, she sometimes eats grapes, strawberries, and apples directly from their bins before paying for them. This behavior—which would have been very embarrassing to her before the stroke—is consistent with damage in another region in the frontal lobe—the prefrontal cortex, which is associated with judgment, reasoning, and impulse control.

Watch It

Watch this video to see an incredible example of the challenges facing a split-brain patient shortly following the surgery to sever her corpus callosum.

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You can view the transcript for “Split Brain mpeg1video” here (opens in new window).

Watch this second video about another patient who underwent a dramatic surgery to prevent her seizures. You’ll learn more about the brain’s ability to change, adapt, and reorganize itself, also known as brain plasticity.

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You can view the transcript for “Brain Plasticity – the story of Jody” here (opens in new window).

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Lobes of the Brain

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Learning Objectives

  • Identify the location and function of the lobes of the brain

Forebrain Structures

The two hemispheres of the cerebral cortex are part of the forebrain (Figure 1), which is the largest part of the brain. The forebrain contains the cerebral cortex and a number of other structures that lie beneath the cortex (called subcortical structures): thalamus, hypothalamus, pituitary gland, and the limbic system (collection of structures). The cerebral cortex, which is the outer surface of the brain, is associated with higher level processes such as consciousness, thought, emotion, reasoning, language, and memory. Each cerebral hemisphere can be subdivided into four lobes, each associated with different functions.
An illustration shows the position and size of the forebrain (the largest portion), midbrain (a small central portion), and hindbrain (a portion in the lower back part of the brain).
Figure 1. The brain and its parts can be divided into three main categories: the forebrain, midbrain, and hindbrain.

Lobes of the Brain

The four lobes of the brain are the frontal, parietal, temporal, and occipital lobes (Figure 2). The frontal lobe is located in the forward part of the brain, extending back to a fissure known as the central sulcus. The frontal lobe is involved in reasoning, motor control, emotion, and language. It contains the motor cortex, which is involved in planning and coordinating movement; the prefrontal cortex, which is responsible for higher-level cognitive functioning; and Broca’s area, which is essential for language production.

An illustration shows the four lobes of the brain.
Figure 2. The lobes of the brain are shown.

People who suffer damage to Broca’s area have great difficulty producing language of any form. For example, Padma was an electrical engineer who was socially active and a caring, involved mother. About twenty years ago, she was in a car accident and suffered damage to her Broca’s area. She completely lost the ability to speak and form any kind of meaningful language. There is nothing wrong with her mouth or her vocal cords, but she is unable to produce words. She can follow directions but can’t respond verbally, and she can read but no longer write. She can do routine tasks like running to the market to buy milk, but she could not communicate verbally if a situation called for it.

Image (a) is a photograph of Phineas Gage holding a metal rod. Image (b) is an illustration of a skull with a metal rod passing through it from the cheek area to the top of the skull.
Figure 3. (a) Phineas Gage holds the iron rod that penetrated his skull in an 1848 railroad construction accident. (b) Gage’s prefrontal cortex was severely damaged in the left hemisphere. The rod entered Gage’s face on the left side, passed behind his eye, and exited through the top of his skull, before landing about 80 feet away. (credit a: modification of work by Jack and Beverly Wilgus

Probably the most famous case of frontal lobe damage is that of a man by the name of Phineas Gage. On September 13, 1848, Gage (age 25) was working as a railroad foreman in Vermont. He and his crew were using an iron rod to tamp explosives down into a blasting hole to remove rock along the railway’s path. Unfortunately, the iron rod created a spark and caused the rod to explode out of the blasting hole, into Gage’s face, and through his skull (Figure 3). Although lying in a pool of his own blood with brain matter emerging from his head, Gage was conscious and able to get up, walk, and speak. But in the months following his accident, people noticed that his personality had changed. Many of his friends described him as no longer being himself. Before the accident, it was said that Gage was a well-mannered, soft-spoken man, but he began to behave in odd and inappropriate ways after the accident. Such changes in personality would be consistent with loss of impulse control—a frontal lobe function.

Beyond the damage to the frontal lobe itself, subsequent investigations into the rod’s path also identified probable damage to pathways between the frontal lobe and other brain structures, including the limbic system. With connections between the planning functions of the frontal lobe and the emotional processes of the limbic system severed, Gage had difficulty controlling his emotional impulses.

However, there is some evidence suggesting that the dramatic changes in Gage’s personality were exaggerated and embellished. Gage’s case occurred in the midst of a 19th century debate over localization—regarding whether certain areas of the brain are associated with particular functions. On the basis of extremely limited information about Gage, the extent of his injury, and his life before and after the accident, scientists tended to find support for their own views, on whichever side of the debate they fell (Macmillan, 1999).

Link to learning

Watch this clip about Phineas Gage to learn more about his accident and injury.

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You can view the transcript for “Phineas Gage (LEGO Stop-Motion Video)” (opens in new window).

Image of the motor cortex, detailing how specific areas correlate to distinct body parts, like the throat, tongue, jaw, lips, face, hands, and other body parts.
Figure 4. Specific body parts like the tongue or fingers are mapped onto certain areas of the brain including the primary motor cortex.

One particularly fascinating area in the frontal lobe is called the “primary motor cortex”. This strip running along the side of the brain is in charge of voluntary movements like waving goodbye, wiggling your eyebrows, and kissing. It is an excellent example of the way that the various regions of the brain are highly specialized. Interestingly, each of our various body parts has a unique portion of the primary motor cortex devoted to it. Each individual finger has about as much dedicated brain space as your entire leg. Your lips, in turn, require about as much dedicated brain processing as all of your fingers and your hand combined!

A diagram shows the organization in the somatosensory cortex, with functions for these parts in this proximal sequential order: toes, ankles, knees, hips, trunk, shoulders, elbows, wrists, hands, fingers, thumbs, neck, eyebrows and eyelids, eyeballs, face, lips, jaw, tongue, salivation, chewing, and swallowing.
Figure 5. Spatial relationships in the body are mirrored in the organization of the somatosensory cortex.

Because the cerebral cortex in general, and the frontal lobe in particular, are associated with such sophisticated functions as planning and being self-aware they are often thought of as a higher, less primal portion of the brain. Indeed, other animals such as rats and kangaroos while they do have frontal regions of their brain do not have the same level of development in the cerebral cortices. The closer an animal is to humans on the evolutionary tree—think chimpanzees and gorillas, the more developed is this portion of their brain.

The brain’s parietal lobe is located immediately behind the frontal lobe, and is involved in processing information from the body’s senses. It contains the somatosensory cortex, which is essential for processing sensory information from across the body, such as touch, temperature, and pain. The somatosensory cortex is organized topographically, which means that spatial relationships that exist in the body are maintained on the surface of the somatosensory cortex. For example, the portion of the cortex that processes sensory information from the hand is adjacent to the portion that processes information from the wrist.

An illustration shows the locations of Broca’s and Wernicke’s areas.
Figure 6. Damage to either Broca’s area or Wernicke’s area can result in language deficits. The types of deficits are very different, however, depending on which area is affected.

The temporal lobe is located on the side of the head (temporal means “near the temples”), and is associated with hearing, memory, emotion, and some aspects of language. The auditory cortex, the main area responsible for processing auditory information, is located within the temporal lobe. Wernicke’s area, important for speech comprehension, is also located here. Whereas individuals with damage to Broca’s area have difficulty producing language, those with damage to Wernicke’s area can produce sensible language, but they are unable to understand it.

The occipital lobe is located at the very back of the brain, and contains the primary visual cortex, which is responsible for interpreting incoming visual information. The occipital cortex is organized retinotopically, which means there is a close relationship between the position of an object in a person’s visual field and the position of that object’s representation on the cortex. You will learn much more about how visual information is processed in the occipital lobe when you study sensation and perception.

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Food for Thought

Consider the following advice from Joseph LeDoux, a professor of neuroscience and psychology at New York University, as you learn about the specific parts of the brain:

Be suspicious of any statement that says a brain area is a center responsible for some function. The notion of functions being products of brain areas or centers is left over from the days when most evidence about brain function was based on the effects of brain lesions localized to specific areas. Today, we think of functions as products of systems rather than of areas. Neurons in areas contribute because they are part of a system. The amygdala, for example, contributes to threat detection because it is part of a threat detection system. And just because the amygdala contributes to threat detection does not mean that threat detection is the only function to which it contributes. Amygdala neurons, for example, are also components of systems that process the significance of stimuli related to eating, drinking, sex, and addictive drugs.

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The Limbic System and Other Brain Areas

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Learning Objectives

  • Identify and describe the role of the parts of the limbic system, the midbrain, and hindbrain

Areas of the Forebrain

Other areas of the forebrain (which includes the lobes that you learned about previously), are the parts located beneath the cerebral cortex, including the thalamus and the limbic system. The thalamus is a sensory relay for the brain. All of our senses, with the exception of smell, are routed through the thalamus before being directed to other areas of the brain for processing (Figure 1).
An illustration shows the location of the thalamus in the brain.
Figure 1. The thalamus serves as the relay center of the brain where most senses are routed for processing.

The limbic system is involved in processing both emotion and memory. Interestingly, the sense of smell projects directly to the limbic system; therefore, not surprisingly, smell can evoke emotional responses in ways that other sensory modalities cannot. The limbic system is made up of a number of different structures, but three of the most important are the hippocampus, the amygdala, and the hypothalamus (Figure 2). The hippocampus is an essential structure for learning and memory. The amygdala is involved in our experience of emotion and in tying emotional meaning to our memories. The hypothalamus regulates a number of homeostatic processes, including the regulation of body temperature, appetite, and blood pressure. The hypothalamus also serves as an interface between the nervous system and the endocrine system and in the regulation of sexual motivation and behavior.

An illustration shows the locations of parts of the brain involved in the limbic system: the hypothalamus, amygdala, and hippocampus.
Figure 2. The limbic system is involved in mediating emotional response and memory.

The Case of Henry Molaison (H.M.)

In 1953, Henry Gustav Molaison (H. M.) was a 27-year-old man who experienced severe seizures. In an attempt to control his seizures, H. M. underwent brain surgery to remove his hippocampus and amygdala. Following the surgery, H.M’s seizures became much less severe, but he also suffered some unexpected—and devastating—consequences of the surgery: he lost his ability to form many types of new memories. For example, he was unable to learn new facts, such as who was president of the United States. He was able to learn new skills, but afterward he had no recollection of learning them. For example, while he might learn to use a computer, he would have no conscious memory of ever having used one. He could not remember new faces, and he was unable to remember events, even immediately after they occurred. Researchers were fascinated by his experience, and he is considered one of the most studied cases in medical and psychological history (Hardt, Einarsson, & Nader, 2010; Squire, 2009). Indeed, his case has provided tremendous insight into the role that the hippocampus plays in the consolidation of new learning into explicit memory.

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Link to Learning

Clive Wearing, an accomplished musician, lost the ability to form new memories when his hippocampus was damaged through illness. Check out the first few minutes of this documentary video for an introduction to this man and his condition.

Midbrain and Hindbrain Structures

The midbrain is comprised of structures located deep within the brain, between the forebrain and the hindbrain. The reticular formation is centered in the midbrain, but it actually extends up into the forebrain and down into the hindbrain. The reticular formation is important in regulating the sleep/wake cycle, arousal, alertness, and motor activity.

The substantia nigra (Latin for “black substance”) and the ventral tegmental area (VTA) are also located in the midbrain (Figure 3). Both regions contain cell bodies that produce the neurotransmitter dopamine, and both are critical for movement. Degeneration of the substantia nigra and VTA is involved in Parkinson’s disease. In addition, these structures are involved in mood, reward, and addiction (Berridge & Robinson, 1998; Gardner, 2011; George, Le Moal, & Koob, 2012).

An illustration shows the location of the substantia negra and VTA in the brain.
Figure 3. The substantia nigra and ventral tegmental area (VTA) are located in the midbrain.

The hindbrain is located at the back of the head and looks like an extension of the spinal cord. It contains the medulla, pons, and cerebellum (Figure 4). The medulla controls the automatic processes of the autonomic nervous system, such as breathing, blood pressure, and heart rate. The word pons literally means “bridge,” and as the name suggests, the pons serves to connect the brain and spinal cord. It also is involved in regulating brain activity during sleep. The medulla, pons, and midbrain together are known as the brainstem.

An illustration shows the location of the pons, medulla, and cerebellum.
Figure 4. The pons, medulla, and cerebellum make up the hindbrain.

The cerebellum (Latin for “little brain”) receives messages from muscles, tendons, joints, and structures in our ear to control balance, coordination, movement, and motor skills. The cerebellum is also thought to be an important area for processing some types of memories. In particular, procedural memory, or memory involved in learning and remembering how to perform tasks, is thought to be associated with the cerebellum. Recall that H. M. was unable to form new explicit memories, but he could learn new tasks. This is likely due to the fact that H. M.’s cerebellum remained intact.

Link to Learning

For a fun recap of the parts of the brain, watch the following short clip from the old cartoon, Pinky and the Brain:

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What Do You Think?: Brain Dead and on Life Support

What would you do if your spouse or loved one was declared brain dead but his or her body was being kept alive by medical equipment? Whose decision should it be to remove a feeding tube? Should medical care costs be a factor?

On February 25, 1990, a Florida woman named Terri Schiavo went into cardiac arrest, apparently triggered by a bulimic episode. She was eventually revived, but her brain had been deprived of oxygen for a long time. Brain scans indicated that there was no activity in her cerebral cortex, and she suffered from severe and permanent cerebral atrophy. Basically, Schiavo was in a vegetative state. Medical professionals determined that she would never again be able to move, talk, or respond in any way. To remain alive, she required a feeding tube, and there was no chance that her situation would ever improve.

On occasion, Schiavo’s eyes would move, and sometimes she would groan. Despite the doctors’ insistence to the contrary, her parents believed that these were signs that she was trying to communicate with them.

After 12 years, Schiavo’s husband argued that his wife would not have wanted to be kept alive with no feelings, sensations, or brain activity. Her parents, however, were very much against removing her feeding tube. Eventually, the case made its way to the courts, both in the state of Florida and at the federal level. By 2005, the courts found in favor of Schiavo’s husband, and the feeding tube was removed on March 18, 2005. Schiavo died 13 days later.

Why did Schiavo’s eyes sometimes move, and why did she groan? Although the parts of her brain that control thought, voluntary movement, and feeling were completely damaged, her brainstem was still intact. Her medulla and pons maintained her breathing and caused involuntary movements of her eyes and the occasional groans. Over the 15-year period that she was on a feeding tube, Schiavo’s medical costs may have topped $7 million (Arnst, 2003).

These questions were brought to popular conscience 25 years ago in the case of Terri Schiavo, and they persist today. In 2013, a 13-year-old girl who suffered complications after tonsil surgery was declared brain dead. There was a battle between her family, who wanted her to remain on life support, and the hospital’s policies regarding persons declared brain dead. In another complicated 2013–14 case in Texas, a pregnant EMT professional declared brain dead was kept alive for weeks, despite her spouse’s directives, which were based on her wishes should this situation arise. In this case, state laws designed to protect an unborn fetus came into consideration until doctors determined the fetus unviable.

Decisions surrounding the medical response to patients declared brain dead are complex. What do you think about these issues?

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Think It Over

You read about H. M.’s memory deficits following the bilateral removal of his hippocampus and amygdala. Have you encountered a character in a book, television program, or movie that suffered memory deficits? How was that character similar to and different from H. M.?

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Brain Imaging

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Learning Objectives

  • Describe the types of techniques available to clinicians and researchers to image or scan the brain
You have learned how brain injury can provide information about the functions of different parts of the brain. Increasingly, however, we are able to obtain that information using brain imaging techniques on individuals who have not suffered brain injury. In this section, we take a more in-depth look at some of the techniques that are available for imaging the brain, including techniques that rely on radiation, magnetic fields, or electrical activity within the brain.

Techniques Involving Radiation

Image (a) shows a brain scan where the brain matter’s appearance is fairly uniform. Image (b) shows a section of the brain that looks different from the surrounding tissue and is labeled “tumor.”
Figure 1. A CT scan can be used to show brain tumors. (a) The image on the left shows a healthy brain, whereas (b) the image on the right indicates a brain tumor in the left frontal lobe. (credit a: modification of work by “Aceofhearts1968″/Wikimedia Commons; credit b: modification of work by Roland Schmitt et al)

A computerized tomography (CT) scan involves taking a number of x-rays of a particular section of a person’s body or brain (Figure 1). The x-rays pass through tissues of different densities at different rates, allowing a computer to construct an overall image of the area of the body being scanned. A CT scan is often used to determine whether someone has a tumor, or significant brain atrophy.

A brain scan shows different parts of the brain in different colors.
Figure 2. A PET scan is helpful for showing activity in different parts of the brain. (credit: Health and Human Services Department, National Institutes of Health)

Positron emission tomography (PET) scans create pictures of the living, active brain (Figure 2). An individual receiving a PET scan drinks or is injected with a mildly radioactive substance, called a tracer. Once in the bloodstream, the amount of tracer in any given region of the brain can be monitored. As brain areas become more active, more blood flows to that area. A computer monitors the movement of the tracer and creates a rough map of active and inactive areas of the brain during a given behavior. PET scans show little detail, are unable to pinpoint events precisely in time, and require that the brain be exposed to radiation; therefore, this technique has been replaced by the fMRI as an alternative diagnostic tool. However, combined with CT, PET technology is still being used in certain contexts. For example, CT/PET scans allow better imaging of the activity of neurotransmitter receptors and open new avenues in schizophrenia research. In this hybrid CT/PET technology, CT contributes clear images of brain structures, while PET shows the brain’s activity.

A brain scan shows brain tissue in gray with some small areas highlighted red.
Figure 3. An fMRI shows activity in the brain over time. This image represents a single frame from an fMRI. (credit: modification of work by Kim J, Matthews NL, Park S.)

Techniques Involving Magnetic Fields

In magnetic resonance imaging (MRI), a person is placed inside a machine that generates a strong magnetic field. The magnetic field causes the hydrogen atoms in the body’s cells to move. When the magnetic field is turned off, the hydrogen atoms emit electromagnetic signals as they return to their original positions. Tissues of different densities give off different signals, which a computer interprets and displays on a monitor.

Functional magnetic resonance imaging (fMRI) operates on the same principles, but it shows changes in brain activity over time by tracking blood flow and oxygen levels. The fMRI provides more detailed images of the brain’s structure, as well as better accuracy in time, than is possible in PET scans (Figure 3). With their high level of detail, MRI and fMRI are often used to compare the brains of healthy individuals to the brains of individuals diagnosed with psychological disorders. This comparison helps determine what structural and functional differences exist between these populations.

Link to Learning

Visit this virtual lab to learn more about MRI and fMRI.

Techniques Involving Electrical Activity

In some situations, it is helpful to gain an understanding of the overall activity of a person’s brain, without needing information on the actual location of the activity. Electroencephalography (EEG) serves this purpose by providing a measure of a brain’s electrical activity. An array of electrodes is placed around a person’s head (Figure 4). The signals received by the electrodes result in a printout of the electrical activity of his or her brain, or brainwaves, showing both the frequency (number of waves per second) and amplitude (height) of the recorded brainwaves, with an accuracy within milliseconds. Such information is especially helpful to researchers studying sleep patterns among individuals with sleep disorders.

A photograph depicts a person looking at a computer screen and using the keyboard and mouse. The person wears a white cap covered in electrodes and wires.
Figure 4. Using caps with electrodes, modern EEG research can study the precise timing of overall brain activities. (credit: SMI Eye Tracking)

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Introduction to Nature and Nurture

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What you’ll learn to do: explain how nature, nurture, and epigenetics influence personality and behavior

This image shows a DNA molecule that is methylated on both strands on the center cytosine. DNA methylation plays an important role for epigenetic gene regulation in development and cancer.

How do we become who we are? Traditionally, people’s answers have placed them in one of two camps: nature or nurture. The one says genes determine an individual while the other claims the environment is the linchpin for development. Since the 16th century, when the terms “nature” and “nurture” first came into use, many people have spent ample time debating which is more important, but these discussions have more often led to ideological cul-de-sacs rather than pinnacles of insight.

New research into epigenetics—the science of how the environment influences genetic expression—is changing the conversation. As psychologist David S. Moore explains in his newest book, The Developing Genome, this burgeoning field reveals that what counts is not what genes you have so much as what your genes are doing. And what your genes are doing is influenced by the ever-changing environment they’re in. Factors like stress, nutrition, and exposure to toxins all play a role in how genes are expressed—essentially which genes are turned on or off. Unlike the static conception of nature or nurture, epigenetic research demonstrates how genes and environments continuously interact to produce characteristics throughout a lifetime.

Learning Objectives

  • Investigate the historic nature vs. nurture debate and describe techniques psychologists use to learn about the origin of traits
  • Explain the basic principles of the theory of evolution by natural selection, genetic variation, and mutation
  • Describe epigenetics and examine how gene-environment interactions are critical for expression of physical and psychological characteristics

The Nature-Nurture Question

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Learning Objectives

  • Investigate the historic nature vs. nurture debate and describe techniques psychologists use to learn about the origin of traits

Nature vs. Nurture Debate

Are you the way you are because you were born that way, or because of the way you were raised? Do your genetics and biology dictate your personality and behavior, or is it your environment and how you were raised? These questions are central to the age-old nature-nurture debate. In the history of psychology, no other question has caused so much controversy and offense: We are so concerned with nature–nurture because our very sense of moral character seems to depend on it. While we may admire the athletic skills of a great basketball player, we think of his height as simply a gift, a payoff in the “genetic lottery.” For the same reason, no one blames a short person for his height or someone’s congenital disability on poor decisions: To state the obvious, it’s “not their fault.” But we do praise the concert violinist (and perhaps her parents and teachers as well) for her dedication, just as we condemn cheaters, slackers, and bullies for their bad behavior.The problem is, most human characteristics aren’t usually as clear-cut as height or instrument-mastery, affirming our nature–nurture expectations strongly one way or the other. In fact, even the great violinist might have some inborn qualities—perfect pitch, or long, nimble fingers—that support and reward her hard work. And the basketball player might have eaten a diet while growing up that promoted his genetic tendency for being tall. When we think about our own qualities, they seem under our control in some respects, yet beyond our control in others. And often the traits that don’t seem to have an obvious cause are the ones that concern us the most and are far more personally significant. What about how much we drink or worry? What about our honesty, or religiosity, or sexual orientation? They all come from that uncertain zone, neither fixed by nature nor totally under our own control.

Two similar-looking puppies.
Figure 1. Researchers have learned a great deal about the nature-nurture dynamic by working with animals. But of course many of the techniques used to study animals cannot be applied to people. Separating these two influences in human subjects is a greater research challenge. [Photo: mharrsch]

One major problem with answering nature-nurture questions about people is, how do you set up an experiment? In nonhuman animals, there are relatively straightforward experiments for tackling nature–nurture questions. Say, for example, you are interested in aggressiveness in dogs. You want to test for the more important determinant of aggression: being born to aggressive dogs or being raised by them. You could mate two aggressive dogs—angry Chihuahuas—together, and mate two nonaggressive dogs—happy beagles—together, then switch half the puppies from each litter between the different sets of parents to raise. You would then have puppies born to aggressive parents (the Chihuahuas) but being raised by nonaggressive parents (the Beagles), and vice versa, in litters that mirror each other in puppy distribution. The big questions are: Would the Chihuahua parents raise aggressive beagle puppies? Would the beagle parents raise nonaggressive Chihuahua puppies? Would the puppies’ nature win out, regardless of who raised them? Or… would the result be a combination of nature and nurture? Much of the most significant nature–nurture research has been done in this way (Scott & Fuller, 1998), and animal breeders have been doing it successfully for thousands of years. In fact, it is fairly easy to breed animals for behavioral traits.

With people, however, we can’t assign babies to parents at random, or select parents with certain behavioral characteristics to mate, merely in the interest of science (though history does include horrific examples of such practices, in misguided attempts at “eugenics,” the shaping of human characteristics through intentional breeding). In typical human families, children’s biological parents raise them, so it is very difficult to know whether children act like their parents due to genetic (nature) or environmental (nurture) reasons. Nevertheless, despite our restrictions on setting up human-based experiments, we do see real-world examples of nature-nurture at work in the human sphere—though they only provide partial answers to our many questions. The science of how genes and environments work together to influence behavior is called behavioral genetics. The easiest opportunity we have to observe this is the adoption study. When children are put up for adoption, the parents who give birth to them are no longer the parents who raise them. This setup isn’t quite the same as the experiments with dogs (children aren’t assigned to random adoptive parents in order to suit the particular interests of a scientist) but adoption still tells us some interesting things, or at least confirms some basic expectations. For instance, if the biological child of tall parents were adopted into a family of short people, do you suppose the child’s growth would be affected? What about the biological child of a Spanish-speaking family adopted at birth into an English-speaking family? What language would you expect the child to speak? And what might these outcomes tell you about the difference between height and language in terms of nature-nurture?

Identical twin boys look at each other, one with a straight face and the other with an open-mouth laugh.
Figure 2. Studies focused on twins have lead to important insights about the biological origins of many personality characteristics. [Photo: ethermoon]

Another option for observing nature-nurture in humans involves twin studies. There are two types of twins: monozygotic (MZ) and dizygotic (DZ). Monozygotic twins, also called “identical” twins, result from a single zygote (fertilized egg) and have the same DNA. They are essentially clones. Dizygotic twins, also known as “fraternal” twins, develop from two zygotes and share 50% of their DNA. Fraternal twins are ordinary siblings who happen to have been born at the same time. To analyze nature–nurture using twins, we compare the similarity of MZ and DZ pairs. Sticking with the features of height and spoken language, let’s take a look at how nature and nurture apply: Identical twins, unsurprisingly, are almost perfectly similar for height. The heights of fraternal twins, however, are like any other sibling pairs: more similar to each other than to people from other families, but hardly identical. This contrast between twin types gives us a clue about the role genetics plays in determining height.

Now consider spoken language. If one identical twin speaks Spanish at home, the co-twin with whom she is raised almost certainly does too. But the same would be true for a pair of fraternal twins raised together. In terms of spoken language, fraternal twins are just as similar as identical twins, so it appears that the genetic match of identical twins doesn’t make much difference. Twin and adoption studies are two instances of a much broader class of methods for observing nature-nurture called quantitative genetics, the scientific discipline in which similarities among individuals are analyzed based on how biologically related they are. We can do these studies with siblings and half-siblings, cousins, twins who have been separated at birth and raised separately (Bouchard, Lykken, McGue, & Segal, 1990; such twins are very rare and play a smaller role than is commonly believed in the science of nature–nurture), or with entire extended families (see Plomin, DeFries, Knopik, & Neiderhiser, 2012, for a complete introduction to research methods relevant to nature–nurture).

For better or for worse, contentions about nature–nurture have intensified because quantitative genetics produces a number called a heritability coefficient, varying from 0 to 1, that is meant to provide a single measure of genetics’ influence of a trait. In a general way, a heritability coefficient measures how strongly differences among individuals are related to differences among their genes. But beware: Heritability coefficients, although simple to compute, are deceptively difficult to interpret. Nevertheless, numbers that provide simple answers to complicated questions tend to have a strong influence on the human imagination, and a great deal of time has been spent discussing whether the heritability of intelligence or personality or depression is equal to one number or another.

Microscopic image of DNA
Figure 3. Quantitative genetics uses statistical methods to study the effects that both heredity and environment have on test subjects. These methods have provided us with the heritability coefficient which measures how strongly differences among individuals for a trait are related to differences among their genes. [Image: EMSL]

One reason nature–nurture continues to fascinate us so much is that we live in an era of great scientific discovery in genetics, comparable to the times of Copernicus, Galileo, and Newton, with regard to astronomy and physics. Every day, it seems, new discoveries are made, new possibilities proposed. When Francis Galton first started thinking about nature–nurture in the late-19th century he was very influenced by his cousin, Charles Darwin, but genetics per se was unknown. Mendel’s famous work with peas, conducted at about the same time, went undiscovered for 20 years; quantitative genetics was developed in the 1920s; DNA was discovered by Watson and Crick in the 1950s; the human genome was completely sequenced at the turn of the 21st century; and we are now on the verge of being able to obtain the specific DNA sequence of anyone at a relatively low cost. No one knows what this new genetic knowledge will mean for the study of nature–nurture, but as we will see in the next section, answers to nature–nurture questions have turned out to be far more difficult and mysterious than anyone imagined.

What Have We Learned About Nature–Nurture?

It would be satisfying to be able to say that nature–nurture studies have given us conclusive and complete evidence about where traits come from, with some traits clearly resulting from genetics and others almost entirely from environmental factors, such as childrearing practices and personal will; but that is not the case. Instead, everything has turned out to have some footing in genetics. The more genetically-related people are, the more similar they are—for everything: height, weight, intelligence, personality, mental illness, etc. Sure, it seems like common sense that some traits have a genetic bias. For example, adopted children resemble their biological parents even if they have never met them, and identical twins are more similar to each other than are fraternal twins. And while certain psychological traits, such as personality or mental illness (e.g., schizophrenia), seem reasonably influenced by genetics, it turns out that the same is true for political attitudes, how much television people watch (Plomin, Corley, DeFries, & Fulker, 1990), and whether or not they get divorced (McGue & Lykken, 1992).
Mother splashing with daughter in a fountain.
Figure 4. Research over the last half century has revealed how central genetics are to behavior. The more genetically related people are the more similar they are not just physically but also in terms of personality and behavior. [Photo: 藍川芥 aikawake]

It may seem surprising, but genetic influence on behavior is a relatively recent discovery. In the middle of the 20th century, psychology was dominated by the doctrine of behaviorism, which held that behavior could only be explained in terms of environmental factors. Psychiatry concentrated on psychoanalysis, which probed for roots of behavior in individuals’ early life-histories. The truth is, neither behaviorism nor psychoanalysis is incompatible with genetic influences on behavior, and neither Freud nor Skinner was naive about the importance of organic processes in behavior. Nevertheless, in their day it was widely thought that children’s personalities were shaped entirely by imitating their parents’ behavior, and that schizophrenia was caused by certain kinds of “pathological mothering.”

Whatever the outcome of our broader discussion of nature–nurture, the basic fact that the best predictors of an adopted child’s personality or mental health are found in the biological parents he or she has never met, rather than in the adoptive parents who raised him or her, presents a significant challenge to purely environmental explanations of personality or psychopathology. The message is clear: You can’t leave genes out of the equation. But keep in mind, no behavioral traits are completely inherited, so you can’t leave the environment out altogether, either. Trying to untangle the various ways nature-nurture influences human behavior can be messy, and often common-sense notions can get in the way of good science. One very significant contribution of behavioral genetics that has changed psychology for good can be very helpful to keep in mind: When your subjects are biologically-related, no matter how clearly a situation may seem to point to environmental influence, it is never safe to interpret a behavior as wholly the result of nurture without further evidence. For example, when presented with data showing that children whose mothers read to them often are likely to have better reading scores in third grade, it is tempting to conclude that reading to your kids out loud is important to success in school; this may well be true, but the study as described is inconclusive, because there are genetic as well as environmental pathways between the parenting practices of mothers and the abilities of their children. This is a case where “correlation does not imply causation,” as they say. To establish that reading aloud causes success, a scientist can either study the problem in adoptive families (in which the genetic pathway is absent) or by finding a way to randomly assign children to oral reading conditions.

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Think It Over

  • Is your personality more like one of your parents than the other? If you have a sibling, is his or her personality like yours? In your family, how did these similarities and differences develop? What do you think caused them?
  • Can you think of a human characteristic for which genetic differences would play almost no role? Defend your choice.
  • Do you think the time will come when we will be able to predict almost everything about someone by examining their DNA on the day they are born?
  • Identical twins are more similar than fraternal twins for the trait of aggressiveness, as well as for criminal behavior. Do these facts have implications for the courtroom? If it can be shown that a violent criminal had violent parents, should it make a difference in culpability or sentencing?

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Human Genetics

79

Learning Objectives

  • Explain the basic principles of the theory of evolution by natural selection, genetic variation, and mutation

Psychological researchers study genetics in order to better understand the biological basis that contributes to certain behaviors. While all humans share certain biological mechanisms, we are each unique. And while our bodies have many of the same parts—brains and hormones and cells with genetic codes—these are expressed in a wide variety of behaviors, thoughts, and reactions.

Why do two people infected by the same disease have different outcomes: one surviving and one succumbing to the ailment? How are genetic diseases passed through family lines? Are there genetic components to psychological disorders, such as depression or schizophrenia? To what extent might there be a psychological basis to health conditions such as childhood obesity?

To explore these questions, let’s start by focusing on a specific disease, sickle-cell anemia, and how it might affect two infected sisters. Sickle-cell anemia is a genetic condition in which red blood cells, which are normally round, take on a crescent-like shape (Figure 1). The changed shape of these cells affects how they function: sickle-shaped cells can clog blood vessels and block blood flow, leading to high fever, severe pain, swelling, and tissue damage.

An illustration shows round and sickle-shaped blood cells.
Figure 1. Normal blood cells travel freely through the blood vessels, while sickle-shaped cells form blockages preventing blood flow.

Many people with sickle-cell anemia—and the particular genetic mutation that causes it—die at an early age. While the notion of “survival of the fittest” may suggest that people suffering from this disease have a low survival rate and therefore the disease will become less common, this is not the case. Despite the negative evolutionary effects associated with this genetic mutation, the sickle-cell gene remains relatively common among people of African descent. Why is this? The explanation is illustrated with the following scenario.

Imagine two young women—Luwi and Sena—sisters in rural Zambia, Africa. Luwi carries the gene for sickle-cell anemia; Sena does not carry the gene. Sickle-cell carriers have one copy of the sickle-cell gene but do not have full-blown sickle-cell anemia. They experience symptoms only if they are severely dehydrated or are deprived of oxygen (as in mountain climbing). Carriers are thought to be immune from malaria (an often deadly disease that is widespread in tropical climates) because changes in their blood chemistry and immune functioning prevent the malaria parasite from having its effects (Gong, Parikh, Rosenthal, & Greenhouse, 2013). However, full-blown sickle-cell anemia, with two copies of the sickle-cell gene, does not provide immunity to malaria.

While walking home from school, both sisters are bitten by mosquitos carrying the malaria parasite. Luwi does not get malaria because she carries the sickle-cell mutation. Sena, on the other hand, develops malaria and dies just two weeks later. Luwi survives and eventually has children, to whom she may pass on the sickle-cell mutation.

Link to Learning

Visit this DNA Learning Center website to learn more about how a mutation in DNA leads to sickle-cell anemia.

Malaria is rare in the United States, so the sickle-cell gene benefits nobody: the gene manifests primarily in health problems—minor in carriers, severe in the full-blown disease—with no health benefits for carriers. However, the situation is quite different in other parts of the world. In parts of Africa where malaria is prevalent, having the sickle-cell mutation does provide health benefits for carriers (protection from malaria).

This is precisely the situation that Charles Darwin describes in the theory of evolution by natural selection (Figure 2). In simple terms, the theory states that organisms that are better suited for their environment will survive and reproduce, while those that are poorly suited for their environment will die off. In our example, we can see that as a carrier, Luwi’s mutation is highly adaptive in her African homeland; however, if she resided in the United States (where malaria is much less common), her mutation could prove costly—with a high probability of the disease in her descendants and minor health problems of her own.

Image (a) is a painted portrait of Darwin. Image (b) is a sketch of lines that split apart into branched structures.
Figure 2. (a) In 1859, Charles Darwin proposed his theory of evolution by natural selection in his book, On the Origin of Species. (b) The book contains just one illustration: this diagram that shows how species evolve over time through natural selection.

Dig Deeper: Two Perspectives on Genetics and Behavior

It’s easy to get confused about two fields that study the interaction of genes and the environment, such as the fields of evolutionary psychology and behavioral genetics. How can we tell them apart?

In both fields, it is understood that genes not only code for particular traits, but also contribute to certain patterns of cognition and behavior. Evolutionary psychology focuses on how universal patterns of behavior and cognitive processes have evolved over time. Therefore, variations in cognition and behavior would make individuals more or less successful in reproducing and passing those genes to their offspring. Evolutionary psychologists study a variety of psychological phenomena that may have evolved as adaptations, including fear response, food preferences, mate selection, and cooperative behaviors (Confer et al., 2010).

Whereas evolutionary psychologists focus on universal patterns that evolved over millions of years, behavioral geneticists study how individual differences arise, in the present, through the interaction of genes and the environment. When studying human behavior, behavioral geneticists often employ twin and adoption studies to research questions of interest. Twin studies compare the rates that a given behavioral trait is shared among identical and fraternal twins; adoption studies compare those rates among biologically related relatives and adopted relatives. Both approaches provide some insight into the relative importance of genes and environment for the expression of a given trait.

Link to Learning

Watch this video with renowned evolutionary psychologist Davis Buss for an explanation of how a psychologist approaches evolution and how this approach fits within the field of social science.

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Genetic Variation

Genetic variation, the genetic difference between individuals, is what contributes to a species’ adaptation to its environment. In humans, genetic variation begins with an egg, about 100 million sperm, and fertilization. Fertile women ovulate roughly once per month, releasing an egg from follicles in the ovary. The egg travels, via the fallopian tube, from the ovary to the uterus, where it may be fertilized by a sperm.

The egg and the sperm each contain 23 chromosomes. Chromosomes are long strings of genetic material known as deoxyribonucleic acid (DNA). DNA is a helix-shaped molecule made up of nucleotide base pairs. In each chromosome, sequences of DNA make up genes that control or partially control a number of visible characteristics, known as traits, such as eye color, hair color, and so on. A single gene may have multiple possible variations, or alleles. An allele is a specific version of a gene. So, a given gene may code for the trait of hair color, and the different alleles of that gene affect which hair color an individual has.

When a sperm and egg fuse, their 23 chromosomes pair up and create a zygote with 23 pairs of chromosomes. Therefore, each parent contributes half the genetic information carried by the offspring; the resulting physical characteristics of the offspring (called the phenotype) are determined by the interaction of genetic material supplied by the parents (called the genotype). A person’s genotype is the genetic makeup of that individual. Phenotype, on the other hand, refers to the individual’s inherited physical characteristics (Figure 3).

Image (a) shows the helical structure of DNA. Image (b) shows a person’s face.
Figure 3. (a) Genotype refers to the genetic makeup of an individual based on the genetic material (DNA) inherited from one’s parents. (b) Phenotype describes an individual’s observable characteristics, such as hair color, skin color, height, and build. (credit a: modification of work by Caroline Davis; credit b: modification of work by Cory Zanker)

Most traits are controlled by multiple genes, but some traits are controlled by one gene. A characteristic like cleft chin, for example, is influenced by a single gene from each parent. In this example, we will call the gene for cleft chin “B,” and the gene for smooth chin “b.” Cleft chin is a dominant trait, which means that having the dominant allele either from one parent (Bb) or both parents (BB) will always result in the phenotype associated with the dominant allele. When someone has two copies of the same allele, they are said to be homozygous for that allele. When someone has a combination of alleles for a given gene, they are said to be heterozygous. For example, smooth chin is a recessive trait, which means that an individual will only display the smooth chin phenotype if they are homozygous for that recessive allele (bb).

Imagine that a woman with a cleft chin has a child with a man with a smooth chin. What type of chin will their child have? The answer to that depends on which alleles each parent carries. If the woman is homozygous for cleft chin (BB), her offspring will always have cleft chin. It gets a little more complicated, however, if the mother is heterozygous for this gene (Bb). Since the father has a smooth chin—therefore homozygous for the recessive allele (bb)—we can expect the offspring to have a 50% chance of having a cleft chin and a 50% chance of having a smooth chin (Figure 4).

Image (a) is a Punnett square showing the four possible combinations (Bb, bb, Bb, bb) resulting from the pairing of a bb father and a Bb mother. Image (b) is a close-up photograph showing a cleft chin.
Figure 4. (a) A Punnett square is a tool used to predict how genes will interact in the production of offspring. The capital B represents the dominant allele, and the lowercase b represents the recessive allele. In the example of the cleft chin, where B is cleft chin (dominant allele), wherever a pair contains the dominant allele, B, you can expect a cleft chin phenotype. You can expect a smooth chin phenotype only when there are two copies of the recessive allele, bb. (b) A cleft chin, shown here, is an inherited trait.

Sickle-cell anemia is just one of many genetic disorders caused by the pairing of two recessive genes. For example, phenylketonuria (PKU) is a condition in which individuals lack an enzyme that normally converts harmful amino acids into harmless byproducts. If someone with this condition goes untreated, he or she will experience significant deficits in cognitive function, seizures, and increased risk of various psychiatric disorders. Because PKU is a recessive trait, each parent must have at least one copy of the recessive allele in order to produce a child with the condition (Figure 5).

A Punnett square shows the four possible combinations (NN, Np, Np, pp) resulting from the pairing of two Np parents.
Figure 5. In this Punnett square, N represents the normal allele, and p represents the recessive allele that is associated with PKU. If two individuals mate who are both heterozygous for the allele associated with PKU, their offspring have a 25% chance of expressing the PKU phenotype.

So far, we have discussed traits that involve just one gene, but few human characteristics are controlled by a single gene. Most traits are polygenic: controlled by more than one gene. Height is one example of a polygenic trait, as are skin color and weight.

Where do harmful genes that contribute to diseases like PKU come from? Gene mutations provide one source of harmful genes. A mutation is a sudden, permanent change in a gene. While many mutations can be harmful or lethal, once in a while, a mutation benefits an individual by giving that person an advantage over those who do not have the mutation. Recall that the theory of evolution asserts that individuals best adapted to their particular environments are more likely to reproduce and pass on their genes to future generations. In order for this process to occur, there must be competition—more technically, there must be variability in genes (and resultant traits) that allow for variation in adaptability to the environment. If a population consisted of identical individuals, then any dramatic changes in the environment would affect everyone in the same way, and there would be no variation in selection. In contrast, diversity in genes and associated traits allows some individuals to perform slightly better than others when faced with environmental change. This creates a distinct advantage for individuals best suited for their environments in terms of successful reproduction and genetic transmission.

 

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Gene-Environment Interactions

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Learning Objectives

  • Describe epigenetics and examine how gene-environment interactions are critical for expression of physical and psychological characteristics

Genes do not exist in a vacuum. Although we are all biological organisms, we also exist in an environment that is incredibly important in determining not only when and how our genes express themselves, but also in what combination. Each of us represents a unique interaction between our genetic makeup and our environment; range of reaction is one way to describe this interaction. Range of reaction asserts that our genes set the boundaries within which we can operate, and our environment interacts with the genes to determine where in that range we will fall. For example, if an individual’s genetic makeup predisposes her to high levels of intellectual potential and she is reared in a rich, stimulating environment, then she will be more likely to achieve her full potential than if she were raised under conditions of significant deprivation. According to the concept of range of reaction, genes set definite limits on potential, and environment determines how much of that potential is achieved.

Another perspective on the interaction between genes and the environment is the concept of genetic environmental correlation. Stated simply, our genes influence our environment, and our environment influences the expression of our genes (Figure 1). Not only do our genes and environment interact, as in range of reaction, but they also influence one another bidirectionally. For example, the child of an NBA player would probably be exposed to basketball from an early age. Such exposure might allow the child to realize his or her full genetic, athletic potential. Thus, the parents’ genes, which the child shares, influence the child’s environment, and that environment, in turn, is well suited to support the child’s genetic potential.

Two jigsaw puzzle pieces are shown; one depicts images of houses, and the other depicts a helical DNA strand.
Figure 1. Nature and nurture work together like complex pieces of a human puzzle. The interaction of our environment and genes makes us the individuals we are. (credit “puzzle”: modification of work by Cory Zanker; credit “houses”: modification of work by Ben Salter; credit “DNA”: modification of work by NHGRI)

In another approach to gene-environment interactions, the field of epigenetics looks beyond the genotype itself and studies how the same genotype can be expressed in different ways. In other words, researchers study how the same genotype can lead to very different phenotypes. As mentioned earlier, gene expression is often influenced by environmental context in ways that are not entirely obvious. For instance, identical twins share the same genetic information (identical twins develop from a single fertilized egg that split, so the genetic material is exactly the same in each; in contrast, fraternal twins develop from two different eggs fertilized by different sperm, so the genetic material varies as with non-twin siblings). But even with identical genes, there remains an incredible amount of variability in how gene expression can unfold over the course of each twin’s life. Sometimes, one twin will develop a disease and the other will not. In one example, Tiffany, an identical twin, died from cancer at age 7, but her twin, now 19 years old, has never had cancer. Although these individuals share an identical genotype, their phenotypes differ as a result of how that genetic information is expressed over time. The epigenetic perspective is very different from range of reaction, because here the genotype is not fixed and limited.

Watch It

An interactive or media element has been excluded from this version of the text. You can view it online here: https://pressbooks.online.ucf.edu/lumenpsychology/?p=191

You can view the transcript for “Introducing Epigenetics – Intro to Psychology” here (opens in new window).

Visit this website on genetics for an engaging video primer on the epigenetics of twin studies.

Identical twin toddler girls laying in the snow, wearing pick snowsuits.
Figure 2. Identical twins are the perfect example of epigenetics. Although they share exactly the same DNA, their unique experiences in life will cause some genes (and not others) to express themselves. This is why, over time, identical twins come to look and behave differently. [Image: Inese Dunajeva]

Genes affect more than our physical characteristics. Indeed, scientists have found genetic linkages to a number of behavioral characteristics, ranging from basic personality traits to sexual orientation to spirituality (for examples, see Mustanski et al., 2005; Comings, Gonzales, Saucier, Johnson, & MacMurray, 2000). Genes are also associated with temperament and a number of psychological disorders, such as depression and schizophrenia. So while it is true that genes provide the biological blueprints for our cells, tissues, organs, and body, they also have significant impact on our experiences and our behaviors.

Let’s look at the following findings regarding schizophrenia in light of our three views of gene-environment interactions. Which view do you think best explains this evidence?

In a study of people who were given up for adoption, adoptees whose biological mothers had schizophrenia and who had been raised in a disturbed family environment were much more likely to develop schizophrenia or another psychotic disorder than were any of the other groups in the study:

The study shows that adoptees with high genetic risk were especially likely to develop schizophrenia only if they were raised in disturbed home environments. This research lends credibility to the notion that both genetic vulnerability and environmental stress are necessary for schizophrenia to develop, and that genes alone do not tell the full tale.

DiG Deeper: Parental Investment and programming of stress responses in Offspring

The most comprehensive study to date of variations in parental investment and epigenetic inheritance in mammals is that of the maternally transmitted responses to stress in rats. In rat pups, maternal nurturing (licking and grooming) during the first week of life is associated with long-term programming of individual differences in stress responsiveness, emotionality, cognitive performance, and reproductive behavior (Caldji et al., 1998; Francis, Diorio, Liu, & Meaney, 1999; Liu et al., 1997; Myers, Brunelli, Shair, Squire, & Hofer, 1989; Stern, 1997). In adulthood, the offspring of mothers that exhibit increased levels of pup licking and grooming over the first week of life show increased expression of the glucocorticoid receptor in the hippocampus (a brain structure associated with stress responsivity as well as learning and memory) and a lower hormonal response to stress compared with adult animals reared by low licking and grooming mothers (Francis et al., 1999; Liu et al., 1997). Moreover, rat pups that received low levels of maternal licking and grooming during the first week of life showed decreased histone acetylation and increased DNA methylation of a neuron-specific promoter of the glucocorticoid receptor gene (Weaver et al., 2004). The expression of this gene is then reduced, the number of glucocorticoid receptors in the brain is decreased, and the animals show a higher hormonal response to stress throughout their life.

The effects of maternal care on stress hormone responses and behavior in the offspring can be eliminated in adulthood by pharmacological treatment (HDAC inhibitor trichostatin A, TSA) or dietary amino acid supplementation (methyl donor L-methionine), treatments that influence histone acetylation, DNA methylation, and expression of the glucocorticoid receptor gene (Weaver et al., 2004;Weaver et al., 2005). This series of experiments shows that histone acetylation and DNA methylation of the glucocorticoid receptor gene promoter is a necessary link in the process leading to the long-term physiological and behavioral sequelae of poor maternal care. This points to a possible molecular target for treatments that may reverse or ameliorate the traces of childhood maltreatment.

Several studies have attempted to determine to what extent the findings from model animals are transferable to humans. Examination of post-mortem brain tissue from healthy human subjects found that the human equivalent of the glucocorticoid receptor gene promoter (NR3C1 exon 1F promoter) is also unique to the individual (Turner, Pelascini, Macedo, & Muller, 2008). A similar study examining newborns showed that methylation of the glucocorticoid receptor gene promoter maybe an early epigenetic marker of maternal mood and risk of increased hormonal responses to stress in infants 3 months of age (Oberlander et al., 2008).

Although further studies are required to examine the functional consequence of this DNA methylation, these findings are consistent with our studies in the neonate and adult offspring of low licking and grooming mothers that show increased DNA methylation of the promoter of the glucocorticoid receptor gene, decreased glucocorticoid receptor gene expression, and increased hormonal responses to stress (Weaver et al., 2004).

Examination of brain tissue from suicide victims found that the human glucocorticoid receptor gene promoter is also more methylated in the brains of individuals who had experienced maltreatment during childhood (McGowan et al., 2009). Examination of blood samples from adult patients with bipolar disorder, who also retrospectively reported on their experiences of childhood abuse and neglect, found that the degree of DNA methylation of the human glucocorticoid receptor gene promoter was strongly positively related to the reported experience of childhood maltreatment decades earlier.

Watch this video to see another example of how diet can alter the phenotype of genetically identical mice.

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Putting It Together: Biopsychology

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Learning Objectives

In this module, you learned to

  • identify the basic structures of a neuron, the function of each structure, and how messages travel through the neuron
  • describe the role of the nervous system and endocrine systems
  • identify and describe the parts of the brain
  • explain how nature, nurture, and epigenetics influence personality and behavior

Read the following abstract from Lane Beckes, James A. Coan, and Karen Hasselmo’s 2012 study, “Familiarity promotes the blurring of self and other in the neural representation of threat.”

Neurobiological investigations of empathy often support an embodied simulation account. Using functional magnetic resonance imaging (fMRI), we monitored statistical associations between brain activations indicating self-focused threat to those indicating threats to a familiar friend or an unfamiliar stranger. Results in regions such as the anterior insula, putamen and supramarginal gyrus indicate that self-focused threat activations are robustly correlated with friend-focused threat activations but not stranger-focused threat activations. These results suggest that one of the defining features of human social bonding may be increasing levels of overlap between neural representations of self and other. This article presents a novel and important methodological approach to fMRI empathy studies, which informs how differences in brain activation can be detected in such studies and how covariate approaches can provide novel and important information regarding the brain and empathy.

Did you recognize any of the concepts discussed in this module? This study used fMRI to examine the brain activation of people as they looked at cues and received, or were threatened with receiving, mild electric shocks while holding hands with either a friend or a stranger. The results showed the expected response—brain activation in the anterior insula, putamen, and supramarginal gyrus when a person was threatened with a shock. What was remarkable, however, was that people showed nearly the same brain activation when a friend was threatened with the shock, but not a stranger. This provides insight into studies on empathy, and the idea that the concept of “self” can expand to include others as well.

As you can see, there is a limitless amount of information that could be studied on the brain. Neuroscience is a relatively new field, but the more research that is done, the more it appears that much of human behavior and mental processes—the key interests for psychological study—are intimately intertwined with activity in the brain. Understanding the brain is important no matter what type of psychology you will be involved with, because its effects permeate all human behavior.

Watch IT

The more we learn about the brain and its functioning, the better able we are to work towards repairing the brain or mimicking its capabilities. These advances in research lead to medical discoveries and breakthroughs, such as the one explained in the following video:

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You can view the transcript for “The nerve bypass: how to move a paralysed hand” here (opens in new window).

Discussion: Biopsychology

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Using Your Brain

Step 1: Write a discussion post of at least 150 words based on the following prompt (answer both questions):

Step 2: In a productive post that facilitates discussion, comment on at least TWO other posts with at least 75 words each. Add your own thoughts about the parts of the brain and methods used to study it.

States of Consciousness

VIII

Why It Matters: States of Consciousness

83

A painting shows two children sleeping.
Figure 1. Sleep, which we all experience, is a quiet and mysterious pause in our daily lives. Two sleeping children are depicted in this 1895 oil painting titled Zwei schlafende Mädchen auf der Ofenbank, which translates as “two sleeping girls on the stove,” by Swiss painter Albert Anker.

Our lives involve regular, dramatic changes in the degree to which we are aware of our surroundings and our internal states. While awake, we feel alert and aware of the many important things going on around us. Our experiences change dramatically while we are in deep sleep and once again when we are dreaming. Sometimes, we seek to alter our awareness and experience by using psychoactive drugs; that is, drugs that alter the central nervous system and produce a change of consciousness or a deep meditative state. Consciousness is an awareness of external and internal stimuli. As discussed in the module on the biology of psychology, the brain activity during different phases of consciousness produces characteristic brain waves, which can be observed by electroencephalography (EEG) and other types of analysis.

This module will discuss states of consciousness with a particular emphasis on sleep. You’ll learn about the different stages of sleep, sleep disorders as well as the altered states of consciousness produced by psychoactive drugs, hypnosis, and meditation.

 

Module References

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Introduction to Consciousness and Rhythms

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What you’ll learn to do: describe consciousness and biological rhythms

consciousnessimage

Are you tired? Have you ever pulled an all-nighter? How did you feel the next day? Do you think your lack of sleep impacted your behavior? Chances are, you could answer that question with a resounding, “yes!”. Because psychologists are interested in mental processes and behavior, it’s essential to study consciousness, or our awareness, as humans. States of consciousness vary over the course of the day and throughout our lives, and sleep plays a major role in alertness levels. Important factors in daily changes in consciousness are biological rhythms, and, more specifically, the circadian rhythms generated by the suprachiasmatic nucleus. Typically, our biological clocks are aligned with our external environment, and light tends to be an important cue in setting this clock. When people travel across multiple time zones or work rotating shifts, they can experience disruptions of their circadian cycles that can lead to insomnia, sleepiness, and decreased alertness. If people go extended periods of time without sleep, they will accrue a sleep debt and potentially experience a number of adverse psychological and physiological consequences.

Learning Objectives

  • Describe consciousness and circadian rhythms
  • Explain disruptions in biological rhythms, including sleep debt

Consciousness and Biological Rhythms

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Learning Objectives

  • Describe consciousness and circadian rhythms

Consciousness describes our awareness of internal and external stimuli. Awareness of internal stimuli includes feeling pain, hunger, thirst, sleepiness, and being aware of our thoughts and emotions. Awareness of external stimuli includes seeing the light from the sun, feeling the warmth of a room, and hearing the voice of a friend.

We experience different states of consciousness and different levels of awareness on a regular basis. We might even describe consciousness as a continuum that ranges from full awareness to a deep sleep. Sleep is a state marked by relatively low levels of physical activity and reduced sensory awareness that is distinct from periods of rest that occur during wakefulness. Wakefulness is characterized by high levels of sensory awareness, thought, and behavior. In between these extremes are states of consciousness related to daydreaming, intoxication as a result of alcohol or other drug use, meditative states, hypnotic states, and altered states of consciousness following sleep deprivation. We might also experience unconscious states of being via drug-induced anesthesia for medical purposes. Often, we are not completely aware of our surroundings, even when we are fully awake. For instance, have you ever daydreamed while driving home from work or school without really thinking about the drive itself? You were capable of engaging in the all of the complex tasks involved with operating a motor vehicle even though you were not aware of doing so. Many of these processes, like much of psychological behavior, are rooted in our biology.

Biological Rhythms

Biological rhythms are internal rhythms of biological activity. A woman’s menstrual cycle is an example of a biological rhythm—a recurring, cyclical pattern of bodily changes. One complete menstrual cycle takes about 28 days—a lunar month—but many biological cycles are much shorter. Biological rhythms such as the menstrual cycle are called infradian rhythms because they last longer than 24 hours, and others that last less than 24 hours are called ultradian rhythms. Changes in body temperature and alertness that fluctuate cyclically over a 24-hour period (Figure 1) are examples of a circadian rhythm. A circadian rhythm is a biological rhythm that takes place over a period of about 24 hours. Alertness is associated with higher body temperatures, and sleepiness with lower body temperatures.

A line graph is titled “Circadian Change in Body Temperature (Source: Waterhouse et al., 2012).” The y-axis, is labeled “temperature (degrees Fahrenheit),” ranges from 97.2 to 99.3. The x-axis, which is labeled “time,” begins at 12:00 A.M. and ends at 4:00 A.M. the following day. The subjects slept from 12:00 A.M. until 8:00 A.M. during which time their average body temperatures dropped from around 98.8 degrees at midnight to 97.6 degrees at 4:00 A.M. and then gradually rose back to nearly the same starting temperature by 8:00 A.M. The average body temperature fluctuated slightly throughout the day with an upward tilt, until the next sleep cycle where the temperature again dropped.
Figure 1. This chart illustrates the circadian change in body temperature over 28 hours in a group of eight young men. Body temperature rises throughout the waking day, peaking in the afternoon, and falls during sleep with the lowest point occurring during the very early morning hours.

Our sleep-wake cycle, which is linked to our environment’s natural light-dark cycle, is perhaps the most obvious example of a circadian rhythm, but we also have daily fluctuations in heart rate, blood pressure, blood sugar, and body temperature. Some circadian rhythms play a role in changes in our state of consciousness.

Research indicates that humans (as well as other animals and plants) have a biological clock, or an innate timing device, comprised of specific molecules (proteins) that interact in cells throughout the body. Biological clocks are found in nearly every tissue and organ. Researchers have identified similar genes in people, fruit flies, mice, fungi, and several other organisms that are responsible for making the clock’s components. In the brain, the hypothalamus, which lies above the pituitary gland, is a main center of homeostasis. Homeostasis is the tendency to maintain a balance, or optimal level, within a biological system. In people, the brain’s clock mechanism is located in an area of the hypothalamus known as the suprachiasmatic nucleus (SCN). The SCN is comprised of about 20,000 nerve cells. The axons of light-sensitive neurons in the retina provide information to the SCN based on the amount of light present, allowing this internal clock to be synchronized with the outside world (Klein, Moore, & Reppert, 1991; Welsh, Takahashi, & Kay, 2010) (Figure 2).

In this graphic, the outline of a person’s head facing left is situated to the right of a picture of the sun, which is labeled ”light” with an arrow pointing to a location in the brain where light input is processed. Inside the head is an illustration of a brain with the following parts’ locations identified: Suprachiasmatic nucleus (SCN), Hypothalamus, Pituitary gland, Pineal gland, and Output rhythms: Physiology and Behavior.
Figure 2. The suprachiasmatic nucleus (SCN) serves as the brain’s clock mechanism. The clock sets itself with light information received through projections from the retina.

Problems with Circadian Rhythms

Generally, and for most people, our circadian cycles are aligned with the outside world. For example, most people sleep during the night and are awake during the day. One important regulator of sleep-wake cycles is the hormone melatonin. The pineal gland, an endocrine structure located inside the brain that releases melatonin, is thought to be involved in the regulation of various biological rhythms and of the immune system during sleep (Hardeland, Pandi-Perumal, & Cardinali, 2006). Melatonin release is stimulated by darkness and inhibited by light. People rely on zeitgebers, or external cues, such as light, atmospheric conditions, temperature, and social interactions, to set the appropriate biological clock.

There are individual differences with regards to our sleep-wake cycle. For instance, some people would say they are morning people, while others would consider themselves to be night owls. These individual differences in circadian patterns of activity are known as a person’s chronotype. A person’s individual chronotype may show that a person has a greater propensity to sleep earlier and wake up earlier (a morning lark), or to stay up late and sleep in (a night owl). Morning larks and night owls differ with regard to sleep regulation (Taillard, Philip, Coste, Sagaspe, & Bioulac, 2003). Sleep regulation refers to the brain’s control of switching between sleep and wakefulness as well as coordinating this cycle with the outside world.

Link to Learning

Watch this brief video describing circadian rhythms and how they affect sleep.

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You can view the transcript for “Reprogramming Our Circadian Rhythms for the Modern World” here (opens in new window).

Try It

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Think It Over

We experience shifts in our circadian clocks in the fall and spring of each year with time changes associated with daylight saving time. Is springing ahead or falling back easier for you to adjust to, and why do you think that is?

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Psych in Real Life: Consciousness and Blindsight

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Learning Objectives

  • Explain blindsight and what it reveals about consciousness

If you have already studied about the brain (in the Biopsychology module) then the picture below of the four major lobes of the cerebral cortex should look familiar. Click on the part of the brain that is most heavily involved in vision.

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Blindsight

What do you think would happen if your occipital lobes were damaged? Back in the 1970s, most scientists and physicians would have said, “you would become blind.” It turns out that the answer is more complicated than that.

When he was 8-years old, Graham Young from Oxford, England, was injured in a bicycle accident. Afterwards, he reported that parts of his vision were gone. He told his doctors that he could no longer see anything to the right of his center of vision with either his left or right eye. The left side of his visual world in both eyes was normal. Although he says that he would sometimes walk into objects to his right because he couldn’t see them, when tested fifteen years later, an optician discovered that Mr. Young seemed to respond to visual movements in his “blind” area.

Overhead image of the brain showing how the visual field of both eyes is split and the information cross in the brain so that the left visual field is interpreted in the right hemisphere of the brain, and vice versa.
Figure 1. The illustration shows a top-down view of the neural pathway from the eyes (shown at the top) to the occipital lobes (shown at the bottom). The blue and red lines show the main pathways of information that run from the eyes through the thalamus to the occipital lobes. Because of Graham Young’s damage to his left visual cortex, he cannot see in his right visual field, which affects both eyes.

Graham Young was put into contact with Psychologists Larry Weiskrantz and Elizabeth Warrington, who had worked previously with a person (known as DB) who seemed to have a similar ability to see despite blindness. DB could report shapes and colors, movement and the orientation of objects despite claiming that he could see nothing. He said that he was guessing, but he was usually right about colors and shapes and other characteristics of the objects.

Before we go on, please take a moment to theorize about what might be going on with Graham Young and DB.

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People with blindsight have been tested for their ability to detect color differences, brightness changes, the ability to discriminate between various shapes, as well as tracking movement. Critically, people with blindsight have the conscious experience of blindness, often feeling like they are guessing despite their high level of accuracy.

Blindsight in Action

Here is a brief video of the man who experiences complete blindness because his visual cortex in both hemispheres has been damaged. The researchers (including Dr. Weiskrantz, mentioned above) set up an obstacle course for the man (whose face is blurred to protect his privacy). Watch how well he moves through the objects without help. The man behind him is just there as a safety precaution.

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How can blindsight happen?

Your conscious experience of the world around you, of the choices and decisions you make, and of the emotions and attitudes that motivate you are not the totality of your mental activity or of your brain’s processing of information. Many, perhaps most, psychologists believe that consciousness is only a small part of your total cognitive activity.Source: http://marketingland.com/wp-content/ml-loads/2014/09/iceberg-ss-1920.jpg

A person is considered to be blind if he or she has no conscious experience of the visual world. This conscious experience is based on the flow of information from the eyes through the thalamus in the middle of the brain to the primary visual cortex in the occipital lobe at the back of the brain. If the primary visual cortex is damaged or fails to receive input due to disruption of visual pathway, then the person will not “see” the objects and events that we normally associate with vision.

Overhead image of the brain showing the eyes at the front and demonstrating how messages from the eyes go to the thalamus and then out into other regions of the brain and not just the primary visual cortex in the back.
Figure 2. The green and purple lines represent the primary visual pathway that produces our conscious experience of vision. The red lines roughly represent the secondary pathways that produce visual information with reduced conscious experience, or none at all. (These secondary pathways are not shown precisely).

Blindsight occurs because the visual system has a primary pathway (retina to thalamus to primary visual cortex), but it also has secondary pathways (retina to thalamus to other brain areas). These “other brain areas” include parts of the frontal lobe that guide eye movements, parts of the midbrain that help guide visual attention, and parts of the occipital lobe that process features of the visual perception, including shape, movement, and color.A recent literature review of evidence for the existence of the pathways to the cerebral cortex: Rabbo, F. A., Koch, G., Lefevre, C., & Seizeur, R. (2015). Direct geniculo-extrastriate pathways: A review of the literature. Surgical and Radiologic Anatomy, 37(8), 891-899.

The existence of visual processing areas for isolated features of vision and the fact that these areas get some direct visual information (i.e, input that does not first go to the primary visual cortex) means that it is possible for a person to respond accurately to questions about color or motion or shape without consciously “seeing” the objects that have color or shape or are moving.

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Examining Blindsight

You can see Graham Young as he is tested in the lab in this video that shows him along with psychologist Larry Weizkrantz. The video clip (watch just the first 3 minutes), from a program hosted by neurologist V. S. Ramachandran, goes on to explain a theory as to why blindsight occurs.

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You can view the transcript for “Part 3 – Phantoms In The Brain (Episode 1)” here (opens in new window).

It is important to remember that YOU have these same “unconscious” pathways in your visual system. That means your conscious experience of the visual world may not include all of the visual information you are processing. In other words, you may “know” more than you “see”.

Blindsight is not the only condition that involves unconscious or low-consciousness processing. Other neurological syndromes that have an unconscious element include amnesia, hemispatial neglect, dyslexia, aphasia, and various agnosias.See Consciousness Lost and Found: A Neuropsychological Exploration by Larry Weiskrantz (1997, Oxford University Press). Dr. Weiskrantz is one of the scientists who first described blindsight and studied people with the condition.

Creating Blindsight in the Laboratory

Wouldn’t it be great if we could produce blindsight in the laboratory, in order to better understand visual processing and conscious experience? Maybe with college student volunteers as our subjects? Crazy idea?

Young college student wearing headphones and looking at a notebook, with other books stacked in front of her as she sits on the grass.
Figure 3. Perhaps an unsuspecting student volunteer for transcranial magnetic stimulation.

It turns out, researchers have already done it. Using precisely aimed magnetic pulses, researchers can temporarily disrupt specific areas of the primary visual cortex—the area responsible for conscious vision—without injury. This “blindness” lasts only a fraction of a second, after which vision returns to normal. Would you volunteer to be a participant?

Let’s look at how this works.

TMS: Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) is a procedure used to stimulate neurons in the brain. A device referred to as a “wand” contains an electric coil that generates a magnetic field that in turn creates a small electric current in the brain.The physics of electromagnetism is fascinating, but we will spare you the details here. You may have studied it in some other class, and there are many readable online sources (e.g., Wikipedia). TMS is a great example of the convergence of technology and psychology that is the basis of modern neuroscience. The electric current induces neurons (brain cells) to produce neural signals called action potentials. When action potentials are produced in normal brain processes, they allow neurons to communicate with one another. However, when action potentials are induced by an outside force—here by the TMS wand—they are meaningless and temporarily interfere with communication between neurons. If only a single pulse of electromagnetic energy is produced, then the disruption of the neurons in the targeted region lasts only a fraction of a second. Multiple pulses, called repetitive TMS (rTMS), can produce longer lasting effects. In fact, rTMS is now used by therapists as a treatment for depression and neuropathic pain.

The TMS pulse can be aimed very precisely at a small area of the brain. When the target is the primary visual cortex in the occipital lobe, the TMS pulse can be focused to interfere with neural communication in a tiny region of the of the visual field—so small and occurring for such a short time that you would not even notice. However brief the duration or tiny the affected area, the person receiving the TMS pulse is temporary blind in a small part of the visual field.

Laboratory Research on Unconscious Visual Processing

Dr. Tony Ro is a professor of psychology at the City University of New York. He started studying the connection between consciousness and brain processing more than 20 years ago, and he was one of the earliest researchers to apply TMS technology to the study of visual perception.

In one study, Dr. Ro and graduate students Jennifer Boyer and Stephenie Harrison used TMS technology to see if normal people could process features of visual stimuli without conscious awareness of those stimuli. In other words, they wanted to know if they could they create temporary blindsight in normal subjects in a laboratory.

Remember that blindsight involves unconscious awareness of “features” of objects and events, such as the shape of an object or the direction of its movement. This study focused on two visual features: orientation and color. You and I see orientation (horizontal or vertical) or color (red or green) as part of the experience of some object. A line is horizontal. A box is red. For a person with blindsight, “horizontal” is experienced without any shape associated with it. “Red” is experienced without awareness of the thing that is red. This is the blindsight condition that Dr. Ro and his colleagues wanted to reproduce in the laboratory with the help of volunteer subjects.

Let’s walk through the experiment to understand how it was designed and conducted.

Experiment 1: Unconscious Detection of Orientation

SETUP: The TMS wand was precisely adjusted so the TMS pulse was aimed at the back of the brain (primary visual cortex in the occipital lobes) affecting a very small area of the visual field. For example, imagine the gray box below as a computer screen. The plus sign in the middle is a fixation point. You (the participant in the study) fixate your eyes on this plus sign and hold them there during each trial. The TMS pulse is adjusted to your individual brain so that the area shown as a blue circle (used here only for explanation purposes) is momentarily “blind” when the pulse is active. This is a painstaking process that involves fine calibration of the wand based on feedback from the participant about what he or she can see when different targets are shown on the screen.

Image of a person with a TMS wand held over the head. To the right of that, there is a cross and a white circle with a blue outline. This represents how that circle would temporarily disappear for someone during the TMS stimulation.
Figure 4. Researchers adjusted the TMS wand until the circle would temporarily disappear from a person’s visual field.

TESTING: In one of Dr. Ro’s experiments, participants had to guess the orientation of a line, sometimes when they were temporarily blinded (in a tiny area of the visual cortex) by a TMS pulse. The study consisted of a series of trials. On each trial, either a horizontal or a vertical line was flashed for a fraction of a second on the computer screen in front of the participant. On some of these trials, a TMS pulse disrupted the neurons in the visual cortex. On other trials, there was no TMS pulse. The no-pulse trials served as a kind of control condition.

Click on the slideshow below to see the steps in the vertical line condition. You can use the arrows at the bottom to navigate through the slides.

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An interactive or media element has been excluded from this version of the text. You can view it online here:
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RESULTS:  By chance, if you have to choose between two equally likely options (horizontal or vertical), you would be correct about 50% of the time. On the trials when the subjects reported that they did not “see” anything at all, they correctly guessed the orientation of the line 75% of the time, performance that is significantly better than chance. There was also a strong positive correlation (r = +0.93) between accuracy and confidence: the more confident the subject in his or her guess, the more likely it was that the guess was correct. Keep in mind that, in all of these cases, the subjects started by saying that they saw nothing. That was about 60% of the trials. On the other 40% of trials, the subjects reported seeing something, even if it was a slight blur, and these trials did not count. Not surprisingly, accuracy was near perfect when subjects were conscious of seeing the bar and its orientation.

Variations of the Experiment

A second study using the color of a circle rather than the orientation of a bar was reported in the same paper. Otherwise, the procedures were the same as in the first experiment and the results consistent with the results for the bar orientation experiment.

Testing Blindsight with TMS

Here is a video about a similar experiment conducted by Dr. Ro and his colleagues. The experiment in the video involves detecting yet another feature of objects: their shape. The basic procedures and results are similar to the ones you have just read.

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You can view the transcript for “Seeing Beyond the Visual Cortex – Science Nation” here (opens in new window).

Conclusions from the Research

The experimenters succeeded in producing the experience of blindness using the TMS apparatus, and they also succeeded in producing evidence for unconscious processing of features of the visual experience in normal (college student) volunteers. These results, when put together with the experiences of people with neurological damage, strengthen the case for the theory that some of our visual perception of the world takes place outside of our awareness. The college students have shown that this unconscious processing is not the result of brain damage, but rather is part of our normal perception of the world.

Some Final Words

This module has been about consciousness. It is common to assume that everything we know about the world around us and about our own thoughts and internal experiences must go through the doorway of our conscious mind. Evidence from blindsight is just one of several lines of research that shows that we process more information than we are aware of. Learning just how much this unconscious information can influence our thoughts and actions, our preferences and beliefs, is an important challenge for the rising generation of scientists.

When Biological Clocks Get Disrupted

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Learning Objectives

  • Explain disruptions in biological rhythms, including sleep debt

Disruptions of Normal Sleep

Whether lark, owl, or somewhere in between, there are situations in which a person’s circadian clock gets out of synchrony with the external environment. One way that this happens involves traveling across multiple time zones. When we do this, we often experience jet lag. Jet lag is a collection of symptoms that results from the mismatch between our internal circadian cycles and our environment. These symptoms include fatigue, sluggishness, irritability, and insomnia (i.e., a consistent difficulty in falling or staying asleep for at least three nights a week over a month’s time) (Roth, 2007).

Individuals who do rotating shift work are also likely to experience disruptions in circadian cycles. Rotating shift work refers to a work schedule that changes from early to late on a daily or weekly basis. For example, a person may work from 7:00 a.m. to 3:00 p.m. on Monday, 3:00 a.m. to 11:00 a.m. on Tuesday, and 11:00 a.m. to 7:00 p.m. on Wednesday. In such instances, the individual’s schedule changes so frequently that it becomes difficult for a normal circadian rhythm to be maintained. This often results in sleeping problems, and it can lead to signs of depression and anxiety. These kinds of schedules are common for individuals working in health care professions and service industries, and they are associated with persistent feelings of exhaustion and agitation that can make someone more prone to making mistakes on the job (Gold et al., 1992; Presser, 1995).

Rotating shift work has pervasive effects on the lives and experiences of individuals engaged in that kind of work, which is clearly illustrated in stories reported in a qualitative study that researched the experiences of middle-aged nurses who worked rotating shifts (West, Boughton & Byrnes, 2009). Several of the nurses interviewed commented that their work schedules affected their relationships with their family. One of the nurses said,

If you’ve had a partner who does work regular job 9 to 5 office hours . . . the ability to spend time, good time with them when you’re not feeling absolutely exhausted . . . that would be one of the problems that I’ve encountered. (West et al., 2009, p. 114)

While disruptions in circadian rhythms can have negative consequences, there are things we can do to help us realign our biological clocks with the external environment. Some of these approaches, such as using a bright light as shown in Figure 1, have been shown to alleviate some of the problems experienced by individuals suffering from jet lag or from the consequences of rotating shift work. Because the biological clock is driven by light, exposure to bright light during working shifts and dark exposure when not working can help combat insomnia and symptoms of anxiety and depression (Huang, Tsai, Chen, & Hsu, 2013).

A photograph shows a bright lamp.
Figure 1. Devices like this are designed to provide exposure to bright light to help people maintain a regular circadian cycle. They can be helpful for people working night shifts or for people affected by seasonal variations in light.

Insufficient Sleep

When people have difficulty getting sleep due to their work or the demands of day-to-day life, they accumulate a sleep debt. A person with a sleep debt does not get sufficient sleep on a chronic basis. The consequences of sleep debt include decreased levels of alertness and mental efficiency. Interestingly, since the advent of electric light, the amount of sleep that people get has declined. While we certainly welcome the convenience of having the darkness lit up, we also suffer the consequences of reduced amounts of sleep because we are more active during the nighttime hours than our ancestors were. As a result, many of us sleep less than 7–8 hours a night and accrue a sleep debt. While there is tremendous variation in any given individual’s sleep needs, the National Sleep Foundation (n.d.) cites research to estimate that newborns require the most sleep (between 12 and 18 hours a night) and that this amount declines to just 7–9 hours by the time we are adults.

If you lie down to take a nap and fall asleep very easily, chances are you may have sleep debt. Given that college students are notorious for suffering from significant sleep debt (Hicks, Fernandez, & Pelligrini, 2001; Hicks, Johnson, & Pelligrini, 1992; Miller, Shattuck, & Matsangas, 2010), chances are you and your classmates deal with sleep debt-related issues on a regular basis. The table below shows recommended amounts of sleep at different ages.

Sleep Needs at Different Ages
Age Nightly Sleep Needs
0–3 months 12–18 hours
3 months–1 year 14–15 hours
1–3 years 12–14 hours
3–5 years 11–13 hours
5–10 years 10–11 hours
10–18 years 8–10 hours
18 and older 7–9 hours

Sleep debt and sleep deprivation have significant negative psychological and physiological consequences. As mentioned earlier, lack of sleep can result in decreased mental alertness and cognitive function. In addition, sleep deprivation often results in depression-like symptoms. These effects can occur as a function of accumulated sleep debt or in response to more acute periods of sleep deprivation. It may surprise you to know that sleep deprivation is associated with obesity, increased blood pressure, increased levels of stress hormones, and reduced immune functioning (Banks & Dinges, 2007). Furthermore, individuals suffering from sleep deprivation can also put themselves and others at risk when they put themselves behind the wheel of a car or work with dangerous machinery. Some research suggests that sleep deprivation affects cognitive and motor function as much as, if not more than, alcohol intoxication (Williamson & Feyer, 2000).

An illustration of the top half of a human body identifies the locations in the body that correspond with various adverse affects of sleep deprivation. The brain is labeled with Irritability,” “Cognitive impairment,” “Memory lapses or loss,” “Impaired moral judgement,” “Severe yawning,” “Hallucinations,” and “Symptoms similar to ADHD.” The heart is labeled with Increased heart rate variability and Risk of heart disease. The muscles are labeled with Increased reaction time, Decreased accuracy, Tremors, and Aches. There is an organ near the stomach labeled Risk of diabetes Type 2. Other risks include Growth suppression, Risk of obesity, Decreased temperature, and Impaired immune system.
Figure 2. This figure illustrates some of the negative consequences of sleep deprivation. While cognitive deficits may be the most obvious, many body systems are negatively impacted by lack of sleep. (credit: modification of work by Mikael Häggström)

The amount of sleep we get varies across the lifespan. When we are very young, we spend up to 16 hours a day sleeping. As we grow older, we sleep less. In fact, a meta-analysis, which is a study that combines the results of many related studies, conducted within the last decade indicates that by the time we are 65 years old, we average fewer than 7 hours of sleep per day (Ohayon, Carskadon, Guilleminault, & Vitiello, 2004). As the amount of time we sleep varies over our lifespan, presumably the sleep debt would adjust accordingly.

Try It

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Think It Over

What do you do to adjust to the differences in your daily schedule throughout the week? Are you running a sleep debt when daylight saving time begins or ends?

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Introduction to Sleep and Dreams

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What you’ll learn to do: describe what happens to the brain and body during sleep

A college students falls asleep on her books while studying.

We devote a very large portion of time to sleep, and our brains have complex systems that control various aspects of sleep. Several hormones important for physical growth and maturation are secreted during sleep. While the reason we sleep remains something of a mystery, there is some evidence to suggest that sleep is very important to learning and memory.

You may not feel particularly busy while you sleep, but you’ll learn in this section that your brain and body are quite active. You pass through four different stages of sleep. In this section, you’ll learn more about these sleep stages, dreaming, and sleep disorders.

Learning Objectives

  • Describe areas of the brain and hormone secretions involved in sleep
  • Describe several theories (adaptive and cognitive) aimed at explaining the function of sleep
  • Differentiate between REM and non-REM sleep
  • Describe the stages of sleep
  • Describe and differentiate between theories on why we dream
  • Describe the symptoms and treatments for insomnia, sleep apnea, and narcolepsy

Sleep and Why We Sleep

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Learning Objectives

  • Describe areas of the brain and hormone secretions involved in sleep
  • Describe several theories (adaptive and cognitive) aimed at explaining the function of sleep

We spend approximately one-third of our lives sleeping. Given the average life expectancy for U.S. citizens falls between 73 and 79 years old (Singh & Siahpush, 2006), we can expect to spend approximately 25 years of our lives sleeping. Some animals never sleep (e.g., several fish and amphibian species); other animals can go extended periods of time without sleep and without apparent negative consequences (e.g., dolphins); yet some animals (e.g., rats) die after two weeks of sleep deprivation (Siegel, 2008). Why do we devote so much time to sleeping? Is it absolutely essential that we sleep? This section will consider these questions and explore various explanations for why we sleep.

What is Sleep?

You have read that sleep is distinguished by low levels of physical activity and reduced sensory awareness. As discussed by Siegel (2008), a definition of sleep must also include mention of the interplay of the circadian and homeostatic mechanisms that regulate sleep. Homeostatic regulation of sleep is evidenced by sleep rebound following sleep deprivation. Sleep rebound refers to the fact that a sleep-deprived individual will tend to take longer falling asleep during subsequent opportunities for sleep. Sleep is characterized by certain patterns of activity of the brain that can be visualized using electroencephalography (EEG), and different phases of sleep can be differentiated using EEG as well (Figure 1).

A polysonograph shows 14 rows of waves with some rows appearing visually similar. Rows 1–2, rows 4–7, and rows 9–11 show similar patterns. Rows 4–7 are outlined in read to emphasize the similarity in wave patterns.
Figure 1. This is a segment of a polysonograph (PSG), a recording of several physical variables during sleep. The x-axis shows passage of time in seconds; this record includes 30 seconds of data. The location of the sets of electrode that produced each signal is labeled on the y-axis. The red box encompasses EEG output, and the waveforms are characteristic of a specific stage of sleep. Other curves show other sleep-related data, such as body temperature, muscle activity, and heartbeat.

Sleep-wake cycles seem to be controlled by multiple brain areas acting in conjunction with one another. Some of these areas include the thalamus, the hypothalamus, and the pons. As already mentioned, the hypothalamus contains the SCN—the biological clock of the body—in addition to other nuclei that, in conjunction with the thalamus, regulate slow-wave sleep. The pons is important for regulating rapid eye movement (REM) sleep (National Institutes of Health, n.d.).

Sleep is also associated with the secretion and regulation of a number of hormones from several endocrine glands including: melatonin, follicle stimulating hormone (FSH), luteinizing hormone (LH), and growth hormone (National Institutes of Health, n.d.). You have read that the pineal gland releases melatonin during sleep (Figure 2). Melatonin is thought to be involved in the regulation of various biological rhythms and the immune system (Hardeland et al., 2006). During sleep, the pituitary gland secretes both FSH and LH which are important in regulating the reproductive system (Christensen et al., 2012; Sofikitis et al., 2008). The pituitary gland also secretes growth hormone, during sleep, which plays a role in physical growth and maturation as well as other metabolic processes (Bartke, Sun, & Longo, 2013).

An illustration of a brain shows the locations of the hypothalamus, thalamus, pons, suprachiasmatic nucleus, pituitary gland, and pineal gland.
Figure 2. The pineal and pituitary glands secrete a number of hormones during sleep.

Why Do We Sleep?

Given the central role that sleep plays in our lives and the number of adverse consequences that have been associated with sleep deprivation, one would think that we would have a clear understanding of why it is that we sleep. Unfortunately, this is not the case; however, several hypotheses have been proposed to explain the function of sleep.

Adaptive Function of Sleep

One popular hypothesis of sleep incorporates the perspective of evolutionary psychology. Evolutionary psychology is a discipline that studies how universal patterns of behavior and cognitive processes have evolved over time as a result of natural selection. Variations and adaptations in cognition and behavior make individuals more or less successful in reproducing and passing their genes to their offspring. One hypothesis from this perspective might argue that sleep is essential to restore resources that are expended during the day. Just as bears hibernate in the winter when resources are scarce, perhaps people sleep at night to reduce their energy expenditures. While this is an intuitive explanation of sleep, there is little research that supports this explanation. In fact, it has been suggested that there is no reason to think that energetic demands could not be addressed with periods of rest and inactivity (Frank, 2006; Rial et al., 2007), and some research has actually found a negative correlation between energetic demands and the amount of time spent sleeping (Capellini, Barton, McNamara, Preston, & Nunn, 2008).

Another evolutionary hypothesis of sleep holds that our sleep patterns evolved as an adaptive response to predatory risks, which increase in darkness. Thus we sleep in safe areas to reduce the chance of harm. Again, this is an intuitive and appealing explanation for why we sleep. Perhaps our ancestors spent extended periods of time asleep to reduce attention to themselves from potential predators. Comparative research indicates, however, that the relationship that exists between predatory risk and sleep is very complex and equivocal. Some research suggests that species that face higher predatory risks sleep fewer hours than other species (Capellini et al., 2008), while other researchers suggest there is no relationship between the amount of time a given species spends in deep sleep and its predation risk (Lesku, Roth, Amlaner, & Lima, 2006).

It is quite possible that sleep serves no single universally adaptive function, and different species have evolved different patterns of sleep in response to their unique evolutionary pressures. While we have discussed the negative outcomes associated with sleep deprivation, it should be pointed out that there are many benefits that are associated with adequate amounts of sleep. A few such benefits listed by the National Sleep Foundation (n.d.) include maintaining healthy weight, lowering stress levels, improving mood, and increasing motor coordination, as well as a number of benefits related to cognition and memory formation.

Cognitive Function of Sleep

Another theory regarding why we sleep involves sleep’s importance for cognitive function and memory formation (Rattenborg, Lesku, Martinez-Gonzalez, & Lima, 2007). Indeed, we know sleep deprivation results in disruptions in cognition and memory deficits (Brown, 2012), leading to impairments in our abilities to maintain attention, make decisions, and recall long-term memories. Moreover, these impairments become more severe as the amount of sleep deprivation increases (Alhola & Polo-Kantola, 2007). Furthermore, slow-wave sleep after learning a new task can improve resultant performance on that task (Huber, Ghilardi, Massimini, & Tononi, 2004) and seems essential for effective memory formation (Stickgold, 2005). Understanding the impact of sleep on cognitive function should help you understand that cramming all night for a test may be not effective and can even prove counterproductive.

Watch IT

Watch this video to learn more about the function of sleep and the harmful effects of sleep deprivation.

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Sleep has also been associated with other cognitive benefits. Research indicates that included among these possible benefits are increased capacities for creative thinking (Cai, Mednick, Harrison, Kanady, & Mednick, 2009; Wagner, Gais, Haider, Verleger, & Born, 2004), language learning (Fenn, Nusbaum, & Margoliash, 2003; Gómez, Bootzin, & Nadel, 2006), and inferential judgments (Ellenbogen, Hu, Payne, Titone, & Walker, 2007). It is possible that even the processing of emotional information is influenced by certain aspects of sleep (Walker, 2009).

Watch It

Learn about the connection between memory and sleep in the following clip:

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Try It

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Think It Over

Have you (or someone you know) ever experienced significant periods of sleep deprivation because of simple insomnia, high levels of stress, or as a side effect from a medication? What were the consequences of missing out on sleep?

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Stages of Sleep

90

Learning Objectives

  • Differentiate between REM and non-REM sleep
  • Describe the stages of sleep

Sleep is not a uniform state of being. Instead, sleep is composed of several different stages that can be differentiated from one another by the patterns of brain wave activity that occur during each stage. These changes in brain wave activity can be visualized using EEG and are distinguished from one another by both the frequency and amplitude of brain waves. Sleep can be divided into two different general phases: REM sleep and non-REM (NREM) sleep. Rapid eye movement (REM) sleep is characterized by darting movements of the eyes under closed eyelids. Brain waves during REM sleep appear very similar to brain waves during wakefulness. In contrast, non-REM (NREM) sleep is subdivided into three stages distinguished from each other and from wakefulness by characteristic patterns of brain waves. The first three stages of sleep are NREM sleep, while the fourth and final stage of sleep is REM sleep. In this section, we will discuss each of these stages of sleep and their associated patterns of brain wave activity.

[Note that psychologists originally identified four stages of non-REM sleep, but these were revised in 2008, resulting in just three distinct phases of NREM sleep. You will see that stage 3 of NREM sleep is sometimes presented as both stage 3 and stage 4 in various texts.]

NREM Stages of Sleep

The first stage of NREM sleep is known as stage 1 sleep. Stage 1 sleep is a transitional phase that occurs between wakefulness and sleep, the period during which we drift off to sleep. During this time, there is a slowdown in both the rates of respiration and heartbeat. In addition, stage 1 sleep involves a marked decrease in both overall muscle tension and core body temperature.

In terms of brain wave activity, stage 1 sleep is associated with both alpha and theta waves. The early portion of stage 1 sleep produces alpha waves, which are relatively low frequency (8–13Hz), high amplitude patterns of electrical activity (waves) that become synchronized. This pattern of brain wave activity resembles that of someone who is very relaxed, yet awake. As an individual continues through stage 1 sleep, there is an increase in theta wave activity. Theta waves are even lower frequency (4–7 Hz), higher amplitude brain waves than alpha waves. It is relatively easy to wake someone from stage 1 sleep; in fact, people often report that they have not been asleep if they are awoken during stage 1 sleep.

A graph has a y-axis labeled “EEG” and an x-axis labeled “time (seconds.) Plotted along the y-axis and moving upward are the stages of sleep. First is REM, followed by Stage 3 and 4 NREM Delta, Stage 2 NREM Theta (sleep spindles; K-complexes), Stage 1 NREM Alpha, and Awake. Charted on the x axis is Time in seconds from 2–20 in 2 second intervals. Each sleep stage has associated wavelengths of varying amplitude and frequency. Relative to the others, “awake” has a very close wavelength and a medium amplitude. Stage 1 is characterized by a generally uniform wavelength and a relatively low amplitude which doubles and quickly reverts to normal every 2 seconds. Stage 2 is comprised of a similar wavelength as stage 1. It introduces the K-complex from seconds 10 through 12 which is a short burst of doubled or tripled amplitude and decreased wavelength. Stages 3 shows a more uniform wave with gradually increasing amplitude. Finally, REM sleep looks much like stage 2 without the K-complex.
Figure 1. Brainwave activity changes dramatically across the different stages of sleep.

As we move into stage 2 sleep, the body goes into a state of deep relaxation. Theta waves still dominate the activity of the brain, but they are interrupted by brief bursts of activity known as sleep spindles (Figure 3). A sleep spindle is a rapid burst of higher frequency brain waves that may be important for learning and memory (Fogel & Smith, 2011; Poe, Walsh, & Bjorness, 2010). In addition, the appearance of K-complexes is often associated with stage 2 sleep. A K-complex is a very high amplitude pattern of brain activity that may in some cases occur in response to environmental stimuli. Thus, K-complexes might serve as a bridge to higher levels of arousal in response to what is going on in our environments (Halász, 1993; Steriade & Amzica, 1998).

A graph has an x-axis labeled “time” and a y-axis labeled “voltage. A line illustrates brainwaves, with two areas labeled “sleep spindle” and “k-complex”. The area labeled “sleep spindle” has decreased wavelength and moderately increased amplitude, while the area labeled “k-complex” has significantly high amplitude and longer wavelength.
Figure 3. Stage 2 sleep is characterized by the appearance of both sleep spindles and K-complexes.

Stage 3 of sleep is often referred to as deep sleep or slow-wave sleep because these stages are characterized by low frequency (up to 4 Hz), high amplitude delta waves (Figure 4). During this time, an individual’s heart rate and respiration slow dramatically. It is much more difficult to awaken someone from sleep during stage 3 than during earlier stages. Interestingly, individuals who have increased levels of alpha brain wave activity (more often associated with wakefulness and transition into stage 1 sleep) during stage 3 often report that they do not feel refreshed upon waking, regardless of how long they slept (Stone, Taylor, McCrae, Kalsekar, & Lichstein, 2008).

Polysonograph a shows the pattern of delta waves, which are low frequency and high amplitude. Delta waves are found mostly in stage 4 of sleep.
Figure 4. Delta waves, which are low frequency and high amplitude, characterize slow-wave stage 3 sleep.

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REM Sleep

As mentioned earlier, REM sleep is marked by rapid movements of the eyes. The brain waves associated with this stage of sleep are very similar to those observed when a person is awake, as shown in Figure 5, and this is the period of sleep in which dreaming occurs. It is also associated with paralysis of muscle systems in the body with the exception of those that make circulation and respiration possible. Therefore, no movement of voluntary muscles occurs during REM sleep in a normal individual; REM sleep is often referred to as paradoxical sleep because of this combination of high brain activity and lack of muscle tone. Like NREM sleep, REM has been implicated in various aspects of learning and memory (Wagner, Gais, & Born, 2001), although there is disagreement within the scientific community about how important both NREM and REM sleep are for normal learning and memory (Siegel, 2001).

Chart A is a polysonograph with the period of rapid eye movement (REM) highlighted.
Figure 5. A period of rapid eye movement is marked by the short red line segment. The brain waves associated with REM sleep, outlined in the red box, look very similar to those seen during wakefulness.

If people are deprived of REM sleep and then allowed to sleep without disturbance, they will spend more time in REM sleep in what would appear to be an effort to recoup the lost time in REM. This is known as the REM rebound, and it suggests that REM sleep is also homeostatically regulated. Aside from the role that REM sleep may play in processes related to learning and memory, REM sleep may also be involved in emotional processing and regulation. In such instances, REM rebound may actually represent an adaptive response to stress in nondepressed individuals by suppressing the emotional salience of aversive events that occurred in wakefulness (Suchecki, Tiba, & Machado, 2012).

While sleep deprivation in general is associated with a number of negative consequences (Brown, 2012), the consequences of REM deprivation appear to be less profound (as discussed in Siegel, 2001). In fact, some have suggested that REM deprivation can actually be beneficial in some circumstances. For instance, REM sleep deprivation has been demonstrated to improve symptoms of people suffering from major depression, and many effective antidepressant medications suppress REM sleep (Riemann, Berger, & Volderholzer, 2001; Vogel, 1975).

It should be pointed out that some reviews of the literature challenge this finding, suggesting that sleep deprivation that is not limited to REM sleep is just as effective or more effective at alleviating depressive symptoms among some patients suffering from depression. In either case, why sleep deprivation improves the mood of some patients is not entirely understood (Giedke & Schwärzler, 2002). Recently, however, some have suggested that sleep deprivation might change emotional processing so that various stimuli are more likely to be perceived as positive in nature (Gujar, Yoo, Hu, & Walker, 2011). The hypnogram below (Figure 6) shows a person’s passage through the stages of sleep.

This is a hypnogram showing the transitions of the sleep cycle during a typical seven hour period of sleep. During the first hour, the person goes through stages 1,2, and 3. In the second hour, sleep oscillates between Stages 2 and 3 before attaining a 30-minute period of REM sleep. The third hour follows the same pattern as the second, but ends with a brief awake period. The fourth hour follows a similar pattern as the third, with a slightly longer REM stage. In the fifth hour, stage 3 is no longer reached. The sleep stages are fluctuating from 2, to 1, to REM, to awake, and then they repeat with shortening intervals until the end of the seventh hour when the person awakens.
Figure 6. This hypnogram illustrates how an individual moves through the various stages of sleep. Deeper NREM sleep occurs early on in the night, while the duration of REM sleep increases as the night progresses.

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Think It Over

Researchers believe that one important function of sleep is to facilitate learning and memory. How does knowing this help you in your college studies? What changes could you make to your study and sleep habits to maximize your mastery of the material covered in class?

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Dreams and Dreaming

91

Learning Objectives

  • Describe and differentiate between theories on why we dream

Dreams

The meaning of dreams varies across different cultures and periods of time. By the late 19th century, German psychiatrist Sigmund Freud had become convinced that dreams represented an opportunity to gain access to the unconscious. By analyzing dreams, Freud thought people could increase self-awareness and gain valuable insight to help them deal with the problems they faced in their lives. Freud made distinctions between the manifest content and the latent content of dreams.

Manifest content is the actual content, or storyline, of a dream. Latent content, on the other hand, refers to the hidden meaning of a dream. For instance, if a woman dreams about being chased by a snake, Freud might have argued that this represents the woman’s fear of sexual intimacy, with the snake serving as a symbol of a man’s penis.

Freud was not the only theorist to focus on the content of dreams. The 20th century Swiss psychiatrist Carl Jung believed that dreams allowed us to tap into the collective unconscious. The collective unconscious, as described by Jung, is a theoretical repository of information he believed to be shared by everyone. According to Jung, certain symbols in dreams reflected universal archetypes with meanings that are similar for all people regardless of culture or location.

The sleep and dreaming researcher Rosalind Cartwright, however, believes that dreams simply reflect life events that are important to the dreamer. Unlike Freud and Jung, Cartwright’s ideas about dreaming have found empirical support. For example, she and her colleagues published a study in which women going through divorce were asked several times over a five month period to report the degree to which their former spouses were on their minds. These same women were awakened during REM sleep in order to provide a detailed account of their dream content. There was a significant positive correlation between the degree to which women thought about their former spouses during waking hours and the number of times their former spouses appeared as characters in their dreams (Cartwright, Agargun, Kirkby, & Friedman, 2006). Recent research (Horikawa, Tamaki, Miyawaki, & Kamitani, 2013) has uncovered new techniques by which researchers may effectively detect and classify the visual images that occur during dreaming by using fMRI for neural measurement of brain activity patterns, opening the way for additional research in this area.

Woman sleeping.
Figure 1. There are many theories about why we dream: the threat-simulation theory sees dreaming as an evolutionary “practice ground” for dealing with threats; the expectation-fulfillment theory says that we use up emotional energy during the night; the activation-synthesis theory claims that dreams are meaningless interpretations of random firings of the brain; the continual-activation theory says that dreams help transfer memories to our long-term memory.

Recently, neuroscientists have also become interested in understanding why we dream. For example, Hobson (2009) suggests that dreaming may represent a state of protoconsciousness. In other words, dreaming involves constructing a virtual reality in our heads that we might use to help us during wakefulness. Among a variety of neurobiological evidence, John Hobson cites research on lucid dreams as an opportunity to better understand dreaming in general. Lucid dreams are dreams in which certain aspects of wakefulness are maintained during a dream state. In a lucid dream, a person becomes aware of the fact that they are dreaming, and as such, they can control the dream’s content (LaBerge, 1990).

Theories on Dreaming

While the Freudian theory of dreaming may be the most well known, and Cartwright’s suggestions on dreaming the most plausible, there are several other theories about the purpose of dreaming. The threat-simulation theory suggests that dreaming should be seen as an ancient biological defense mechanism. Dreams are thought to provide an evolutionary advantage because of their capacity to repeatedly simulate potential threatening events. This process enhances the neurocognitive mechanisms required for efficient threat perception and avoidance.

The expectation-fulfillment theory posits that dreaming serves to discharge emotional arousals (however minor) that haven’t been expressed during the day. This practice frees up space in the brain to deal with the emotional arousals of the next day and allows instinctive urges to stay intact. In effect, the expectation is fulfilled (the action is “completed”) in a metaphorical form so that a false memory is not created. This theory explains why dreams are usually forgotten immediately afterwards.

One prominent neurobiological theory of dreaming is the activation-synthesis theory, which states that dreams don’t actually mean anything. They are merely electrical brain impulses that pull random thoughts and imagery from our memories. The theory posits that humans construct dream stories after they wake up, in a natural attempt to make sense of the nonsensical. However, given the vast documentation of the realistic aspects of human dreaming, as well as indirect experimental evidence that other mammals such as cats also dream, evolutionary psychologists have theorized that dreaming does indeed serve a purpose.

The continual-activation theory proposes that dreaming is a result of brain activation and synthesis. Dreaming and REM sleep are simultaneously controlled by different brain mechanisms. The hypothesis states that the function of sleep is to process, encode, and transfer data from short-term memory to long-term memory through a process called consolidation. However, there is not much evidence to back this up. NREM sleep processes the conscious-related memory (declarative memory), and REM sleep processes the unconscious related memory (procedural memory).

The underlying assumption of continual-activation theory is that, during REM sleep, the unconscious part of the brain is busy processing procedural memory. Meanwhile, the level of activation in the conscious part of the brain descends to a very low level as the inputs from the senses are basically disconnected. This triggers the “continual-activation” mechanism to generate a data stream from the memory stores to flow through to the conscious part of the brain.

Link to Learning

Review the purpose and stages of sleep as well as the reasons why we dream in the following CrashCourse video:

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Sleep Problems and Disorders

92

Learning Objectives

  • Describe the symptoms and treatments for insomnia, sleep apnea, and narcolepsy

Many people experience disturbances in their sleep at some point in their lives. Depending on the population and sleep disorder being studied, between 30% and 50% of the population suffers from a sleep disorder at some point in their lives (Bixler, Kales, Soldatos, Kaels, & Healey, 1979; Hossain & Shapiro, 2002; Ohayon, 1997, 2002; Ohayon & Roth, 2002). This section will describe several sleep disorders as well as some of their treatment options.

Parasomnias

A parasomnia is one of a group of sleep disorders in which unwanted, disruptive motor activity and/or experiences during sleep play a role. Parasomnias can occur in either REM or NREM phases of sleep. Sleepwalking, restless leg syndrome, and night terrors are all examples of parasomnias (Mahowald & Schenck, 2000).

Sleepwalking

In sleepwalking, or somnambulism, the sleeper engages in relatively complex behaviors ranging from wandering about to driving an automobile. During periods of sleepwalking, sleepers often have their eyes open, but they are not responsive to attempts to communicate with them. Sleepwalking most often occurs during slow-wave sleep, but it can occur at any time during a sleep period in some affected individuals (Mahowald & Schenck, 2000).

Historically, somnambulism has been treated with a variety of pharmacotherapies ranging from benzodiazepines to antidepressants. However, the success rate of such treatments is questionable. Guilleminault et al. (2005) found that sleepwalking was not alleviated with the use of benzodiazepines. However, all of their somnambulistic patients who also suffered from sleep-related breathing problems showed a marked decrease in sleepwalking when their breathing problems were effectively treated.

Dig Deeper: A Sleepwalking Defense?

On January 16, 1997, Scott Falater sat down to dinner with his wife and children and told them about difficulties he was experiencing on a project at work. After dinner, he prepared some materials to use in leading a church youth group the following morning, and then he attempted repair the family’s swimming pool pump before retiring to bed. The following morning, he awoke to barking dogs and unfamiliar voices from downstairs. As he went to investigate what was going on, he was met by a group of police officers who arrested him for the murder of his wife (Cartwright, 2004; CNN, 1999).

Yarmila Falater’s body was found in the family’s pool with 44 stab wounds. A neighbor called the police after witnessing Falater standing over his wife’s body before dragging her into the pool. Upon a search of the premises, police found blood-stained clothes and a bloody knife in the trunk of Falater’s car, and he had blood stains on his neck.

Remarkably, Falater insisted that he had no recollection of hurting his wife in any way. His children and his wife’s parents all agreed that Falater had an excellent relationship with his wife and they couldn’t think of a reason that would provide any sort of motive to murder her (Cartwright, 2004).

Scott Falater had a history of regular episodes of sleepwalking as a child, and he had even behaved violently toward his sister once when she tried to prevent him from leaving their home in his pajamas during a sleepwalking episode. He suffered from no apparent anatomical brain anomalies or psychological disorders. It appeared that Scott Falater had killed his wife in his sleep, or at least, that is the defense he used when he was tried for his wife’s murder (Cartwright, 2004; CNN, 1999). In Falater’s case, a jury found him guilty of first degree murder in June of 1999 (CNN, 1999); however, there are other murder cases where the sleepwalking defense has been used successfully. As scary as it sounds, many sleep researchers believe that homicidal sleepwalking is possible in individuals suffering from the types of sleep disorders described below (Broughton et al., 1994; Cartwright, 2004; Mahowald, Schenck, & Cramer Bornemann, 2005; Pressman, 2007).

REM Sleep Behavior Disorder (RBD)

REM sleep behavior disorder (RBD) occurs when the muscle paralysis associated with the REM sleep phase does not occur. Individuals who suffer from RBD have high levels of physical activity during REM sleep, especially during disturbing dreams. These behaviors vary widely, but they can include kicking, punching, scratching, yelling, and behaving like an animal that has been frightened or attacked. People who suffer from this disorder can injure themselves or their sleeping partners when engaging in these behaviors. Furthermore, these types of behaviors ultimately disrupt sleep, although affected individuals have no memories that these behaviors have occurred (Arnulf, 2012).

This disorder is associated with a number of neurodegenerative diseases such as Parkinson’s disease. In fact, this relationship is so robust that some view the presence of RBD as a potential aid in the diagnosis and treatment of a number of neurodegenerative diseases (Ferini-Strambi, 2011). Clonazepam, an anti-anxiety medication with sedative properties, is most often used to treat RBD. It is administered alone or in conjunction with doses of melatonin (the hormone secreted by the pineal gland). As part of treatment, the sleeping environment is often modified to make it a safer place for those suffering from RBD (Zangini, Calandra-Buonaura, Grimaldi, & Cortelli, 2011).

Other Parasomnias

A person with restless leg syndrome has uncomfortable sensations in the legs during periods of inactivity or when trying to fall asleep. This discomfort is relieved by deliberately moving the legs, which, not surprisingly, contributes to difficulty in falling or staying asleep. Restless leg syndrome is quite common and has been associated with a number of other medical diagnoses, such as chronic kidney disease and diabetes (Mahowald & Schenck, 2000). There are a variety of drugs that treat restless leg syndrome: benzodiazepines, opiates, and anticonvulsants (Restless Legs Syndrome Foundation, n.d.).

Night terrors result in a sense of panic in the sufferer and are often accompanied by screams and attempts to escape from the immediate environment (Mahowald & Schenck, 2000). Although individuals suffering from night terrors appear to be awake, they generally have no memories of the events that occurred, and attempts to console them are ineffective. Typically, individuals suffering from night terrors will fall back asleep again within a short time. Night terrors apparently occur during the NREM phase of sleep (Provini, Tinuper, Bisulli, & Lagaresi, 2011). Generally, treatment for night terrors is unnecessary unless there is some underlying medical or psychological condition that is contributing to the night terrors (Mayo Clinic, n.d.).

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Insomnia

While parasomnias are disorders related to the various stages of sleep, other sleep disorders, such as insomnia, are related to sleep in general. Insomnia is a consistent difficulty in falling or staying asleep, and is the most common of the sleep disorders. Individuals with insomnia often experience long delays between the times that they go to bed and actually fall asleep. In addition, these individuals may wake up several times during the night only to find that they have difficulty getting back to sleep. As mentioned earlier, one of the criteria for insomnia involves experiencing these symptoms for at least three nights a week for at least one month’s time (Roth, 2007).

It is not uncommon for people suffering from insomnia to experience increased levels of anxiety about their inability to fall asleep. This becomes a self-perpetuating cycle because increased anxiety leads to increased arousal, and higher levels of arousal make the prospect of falling asleep even more unlikely. Chronic insomnia is almost always associated with feeling overtired and may be associated with symptoms of depression.

There may be many factors that contribute to insomnia, including age, drug use, exercise, mental status, and bedtime routines. Not surprisingly, insomnia treatment may take one of several different approaches. People who suffer from insomnia might limit their use of stimulant drugs (such as caffeine) or increase their amount of physical exercise during the day. Some people might turn to over-the-counter (OTC) or prescribed sleep medications to help them sleep, but this should be done sparingly because many sleep medications result in dependence and alter the nature of the sleep cycle, and they can increase insomnia over time. Those who continue to have insomnia, particularly if it affects their quality of life, should seek professional treatment.

Some forms of psychotherapy, such as cognitive-behavioral therapy, can help sufferers of insomnia. Cognitive-behavioral therapy is a type of psychotherapy that focuses on cognitive processes and problem behaviors. The treatment of insomnia likely would include stress management techniques and changes in problematic behaviors that could contribute to insomnia (e.g., spending more waking time in bed). Cognitive-behavioral therapy has been demonstrated to be quite effective in treating insomnia (Savard, Simard, Ivers, & Morin, 2005; Williams, Roth, Vatthauer, & McCrae, 2013).

Sleep Apnea

Sleep apnea is defined by episodes during which a sleeper’s breathing stops. These episodes can last 10–20 seconds or longer and often are associated with brief periods of arousal. While individuals suffering from sleep apnea may not be aware of these repeated disruptions in sleep, they do experience increased levels of fatigue. Many individuals diagnosed with sleep apnea first seek treatment because their sleeping partners indicate that they snore loudly and/or stop breathing for extended periods of time while sleeping (Henry & Rosenthal, 2013). Sleep apnea is much more common in overweight people and is often associated with loud snoring. Surprisingly, sleep apnea may exacerbate cardiovascular disease (Sánchez-de-la-Torre, Campos-Rodriguez, & Barbé, 2012). While sleep apnea is less common in thin people, anyone, regardless of their weight, who snores loudly or gasps for air while sleeping, should be checked for sleep apnea.

While people are often unaware of their sleep apnea, they are keenly aware of some of the adverse consequences of insufficient sleep. Consider a patient who believed that as a result of his sleep apnea he “had three car accidents in six weeks. They were ALL my fault. Two of them I didn’t even know I was involved in until afterwards” (Henry & Rosenthal, 2013, p. 52). It is not uncommon for people suffering from undiagnosed or untreated sleep apnea to fear that their careers will be affected by the lack of sleep, illustrated by this statement from another patient, “I’m in a job where there’s a premium on being mentally alert. I was really sleepy… and having trouble concentrating…. It was getting to the point where it was kind of scary” (Henry & Rosenthal, 2013, p. 52).

There are two types of sleep apnea: obstructive sleep apnea and central sleep apnea. Obstructive sleep apnea occurs when an individual’s airway becomes blocked during sleep, and air is prevented from entering the lungs. In central sleep apnea, disruption in signals sent from the brain that regulate breathing cause periods of interrupted breathing (White, 2005).

One of the most common treatments for sleep apnea involves the use of a special device during sleep. A continuous positive airway pressure (CPAP) device includes a mask that fits over the sleeper’s nose and mouth, which is connected to a pump that pumps air into the person’s airways, forcing them to remain open, as shown in Figure 1. Some newer CPAP masks are smaller and cover only the nose. This treatment option has proven to be effective for people suffering from mild to severe cases of sleep apnea (McDaid et al., 2009). However, alternative treatment options are being explored because consistent compliance by users of CPAP devices is a problem. Recently, a new EPAP (excitatory positive air pressure) device has shown promise in double-blind trials as one such alternative (Berry, Kryger, & Massie, 2011).

Photograph A shows a CPAP device. Photograph B shows a clear full face CPAP mask attached to a mannequin's head with straps.
Figure 1. (a) A typical CPAP device used in the treatment of sleep apnea is (b) affixed to the head with straps, and a mask that covers the nose and mouth.

SIDS

The “Safe to Sleep” campaign logo shows a baby sleeping and the words “safe to sleep.”
Figure 2. The Safe to Sleep campaign educates the public about how to minimize risk factors associated with SIDS. This campaign is sponsored in part by the National Institute of Child Health and Human Development.

In sudden infant death syndrome (SIDS) an infant stops breathing during sleep and dies. Infants younger than 12 months appear to be at the highest risk for SIDS, and boys have a greater risk than girls. A number of risk factors have been associated with SIDS including premature birth, smoking within the home, and hyperthermia. There may also be differences in both brain structure and function in infants that die from SIDS (Berkowitz, 2012; Mage & Donner, 2006; Thach, 2005).

The substantial amount of research on SIDS has led to a number of recommendations to parents to protect their children (Figure 2). For one, research suggests that infants should be placed on their backs when put down to sleep, and their cribs should not contain any items which pose suffocation threats, such as blankets, pillows or padded crib bumpers (cushions that cover the bars of a crib). Infants should not have caps placed on their heads when put down to sleep in order to prevent overheating, and people in the child’s household should abstain from smoking in the home. Recommendations like these have helped to decrease the number of infant deaths from SIDS in recent years (Mitchell, 2009; Task Force on Sudden Infant Death Syndrome, 2011).

Narcolepsy

Unlike the other sleep disorders described in this section, a person with narcolepsy cannot resist falling asleep at inopportune times. These sleep episodes are often associated with cataplexy, which is a lack of muscle tone or muscle weakness, and in some cases involves complete paralysis of the voluntary muscles. This is similar to the kind of paralysis experienced by healthy individuals during REM sleep (Burgess & Scammell, 2012; Hishikawa & Shimizu, 1995; Luppi et al., 2011). Narcoleptic episodes take on other features of REM sleep. For example, around one third of individuals diagnosed with narcolepsy experience vivid, dream-like hallucinations during narcoleptic attacks (Chokroverty, 2010).

Surprisingly, narcoleptic episodes are often triggered by states of heightened arousal or stress. The typical episode can last from a minute or two to half an hour. Once awakened from a narcoleptic attack, people report that they feel refreshed (Chokroverty, 2010). Obviously, regular narcoleptic episodes could interfere with the ability to perform one’s job or complete schoolwork, and in some situations, narcolepsy can result in significant harm and injury (e.g., driving a car or operating machinery or other potentially dangerous equipment).

Generally, narcolepsy is treated using psychomotor stimulant drugs, such as amphetamines (Mignot, 2012). These drugs promote increased levels of neural activity. Narcolepsy is associated with reduced levels of the signaling molecule hypocretin in some areas of the brain (De la Herrán-Arita & Drucker-Colín, 2012; Han, 2012), and the traditional stimulant drugs do not have direct effects on this system. Therefore, it is quite likely that new medications that are developed to treat narcolepsy will be designed to target the hypocretin system.

There is a tremendous amount of variability among sufferers, both in terms of how symptoms of narcolepsy manifest and the effectiveness of currently available treatment options. This is illustrated by McCarty’s (2010) case study of a 50-year-old woman who sought help for the excessive sleepiness during normal waking hours that she had experienced for several years. She indicated that she had fallen asleep at inappropriate or dangerous times, including while eating, while socializing with friends, and while driving her car. During periods of emotional arousal, the woman complained that she felt some weakness in the right side of her body. Although she did not experience any dream-like hallucinations, she was diagnosed with narcolepsy as a result of sleep testing. In her case, the fact that her cataplexy was confined to the right side of her body was quite unusual. Early attempts to treat her condition with a stimulant drug alone were unsuccessful. However, when a stimulant drug was used in conjunction with a popular antidepressant, her condition improved dramatically.

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Think It Over

What factors might contribute to your own experiences with insomnia?

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Introduction to Drugs and Other States of Consciousness

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What you’ll learn to do: explain how drugs affect consciousness

Psychadelic image from Mandelbrot Set.

While we all experience altered states of consciousness in the form of sleep on a regular basis, some people use drugs and other substances that result in altered states of consciousness as well. This section will present information relating to the use of various psychoactive drugs and problems associated with such use. You’ll also learned about other altered states of consciousness like hypnosis and meditation.

Watch It

This CrashCourse video gives an excellent overview of these altered states:

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You can view the transcript “Altered States: Crash Course Psychology #10” here (opens in new window).

Learning Objectives

  • Describe how substance abuse disorders are diagnosed
  • Explain how depressants impact nervous system activity
  • Identify stimulants and describe how they affect the brain and body
  • Identify opioids and describe how they impact the brain and behavior
  • Describe hallucinogens and how they affect the brain and behavior
  • Compare and contrast between depressants, stimulants, opioids, and hallucinogens
  • Describe hypnosis and meditation

Psychoactive Drugs and Addiction

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Learning Objectives

  • Describe how substance abuse disorders are diagnosed

Substance Abuse Disorders

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) is used by clinicians to diagnose individuals suffering from various psychological disorders. Drug use disorders are addictive disorders, and the criteria for specific substance (drug) use disorders are described in DSM-5. A person who has a substance use disorder often uses more of the substance than they originally intended to and continues to use that substance despite experiencing significant adverse consequences. In individuals diagnosed with a substance use disorder, there is a compulsive pattern of drug use that is often associated with both physical and psychological dependence.

Physical dependence involves changes in normal bodily functions—the user will experience withdrawal from the drug upon cessation of use. In contrast, a person who has psychological dependence has an emotional, rather than physical, need for the drug and may use the drug to relieve psychological distress. Tolerance is linked to physiological dependence, and it occurs when a person requires more and more drug to achieve effects previously experienced at lower doses. Tolerance can cause the user to increase the amount of drug used to a dangerous level—even to the point of overdose and death.

Drug withdrawal includes a variety of negative symptoms experienced when drug use is discontinued. These symptoms usually are opposite of the effects of the drug. For example, withdrawal from sedative drugs often produces unpleasant arousal and agitation. In addition to withdrawal, many individuals who are diagnosed with substance use disorders will also develop tolerance to these substances. Psychological dependence, or drug craving, is a recent addition to the diagnostic criteria for substance use disorder in DSM-5. This is an important factor because we can develop tolerance and experience withdrawal from any number of drugs that we do not abuse. In other words, physical dependence in and of itself is of limited utility in determining whether or not someone has a substance use disorder.

Link to Learning

Read through this fascinating comic created by Stuart McMillen about psychologist’s Bruce Alexander’s Rat Park study on addiction.

For more information on Bruce Alexander’s study and a better understanding of addiction, listen to Johann Hari’s TED Talk, “Everything you think you know about addiction is wrong.”

Drug Categories

The effects of all psychoactive drugs occur through their interactions with our endogenous neurotransmitter systems. Many of these drugs, and their relationships, are shown in Figure 1. As you have learned, drugs can act as agonists or antagonists of a given neurotransmitter system. An agonist facilitates the activity of a neurotransmitter system, and antagonists impede neurotransmitter activity.

The main categories of drugs are depressants, stimulants, and hallucinogens. You’ll learn more about these types drugs in the coming pages.

Four main drug categories are identified by differently colored circles showing overlaps: the four main drug categories are “antipsychotics,” “stimulants,” “depressants,” and “hallucinogens.” The circle titled “Antipsychotics” includes the drug names “Haldol,” “Risperdal,” and “Seroquel.” The circle titled “Stimulants” contains a subcircle titled “Psychmotor stimulants” with the drug names “Amphetamines,” “Khat,” “Ritalin,” and “Cocaine.” The “Stimulants” circle contains another subcircle titled “Methylxanthines” with the drug names “Caffeine,” “Theophylline,” and “Theobromine.” The circle titled “Depressants” contains a subcircle titled “Sedative Hypnotics” with the drug names “Alcohol,” “Barbituates,” “Ether,” and “GHB”; within that circle is a subcircle titled “Minor tranquilizers” with the drug names “Ativan,” “Valium,” and “Xanax.” “Nicotine” falls in the overlap between the “Stimulants” and “Depressants” circles. The circle titled “Depressants” also contains a subcircle titled “Narcotic Analgesics” with the drug names “Opium,” “Codeine,” “Morphine,” “Heroin,” and “DXM.” “DXM” falls in the overlap between the “Depressants” circle and the “Dissociatives” subcircle of the “Hallucinogens” circle. The circle titled “Hallucinogens” contains a subcircle labeled “Dissociatives” including the drug names ”Ketamine,” “PCP,” “Nitrous,” “Amanitas,” and “Salvinorum.” Within that subcircle, “Ketamine,” “PCP,” and “Nitrous” overlap with with the “depressants” circle The circle titled “Hallucinogens” also contains a subcircle titled “Psychadelics” including the drug names “MDMA,” “Mescaline,” “LSD,” “Psilocybin,” “AMT,” “DMT,” and “Ibogaine.” Within that subcircle, “MDMA,” “Mescaline,” “LSD,” “Psilocybin,” and “AMT” fall within the overlap between the “Hallucinogens” and “Stimulants” circles. “Ibogaine” falls within the overlap between the “Psychadelics” and “Dissociatives” subcircles. Outside of all subcircles, “Marijuana” falls within the overlap between the “Stimulants,” “Depressants,” and “Hallucinogens” circles.
Figure 1. This figure illustrates various drug categories and overlap among them. (credit: modification of work by Derrick Snider)

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Alcohol and Other Depressants

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Learning Objectives

  • Explain how depressants impact nervous system activity

Ethanol, which we commonly refer to as alcohol, is in a class of psychoactive drugs known as depressants (Figure 1). A depressant is a drug that tends to suppress central nervous system activity. Other depressants include barbiturates and benzodiazepines. These drugs share in common their ability to serve as agonists of the gamma-Aminobutyric acid (GABA) neurotransmitter system. Because GABA has a quieting effect on the brain, GABA agonists also have a quieting effect; these types of drugs are often prescribed to treat both anxiety and insomnia.

An illustration of a GABA-gated chloride channel in a cell membrane shows receptor sites for barbiturate, benzodiazepine, GABA, alcohol, and neurosteroids, as well as three negatively-charged chloride ions passing through the channel. Each drug type has a specific shape, such as triangular, rectangular or square, which corresponds to a similarly shaped receptor spot.
Figure 1. The GABA-gated chloride (Cl-) channel is embedded in the cell membrane of certain neurons. The channel has multiple receptor sites where alcohol, barbiturates, and benzodiazepines bind to exert their effects. The binding of these molecules opens the chloride channel, allowing negatively-charged chloride ions (Cl-) into the neuron’s cell body. Changing its charge in a negative direction pushes the neuron away from firing; thus, activating a GABA neuron has a quieting effect on the brain.

Acute alcohol administration results in a variety of changes to consciousness. Alcohol intoxication is measured for legal and medical uses in terms of Blood Alcohol Content (BAC). A BAC of 0.10 (0.10% or one-tenth of one percent) means that there are 0.10 g of alcohol for every 100 ml of blood. While a BAC of 0.0 is sober, in the United States a BAC of 0.08 is legally intoxicated, and above that is considered very impaired. BAC levels above 0.40 are potentially fatal. At rather low doses, alcohol use is associated with feelings of euphoria. As the dose increases, people report feeling sedated. Generally, alcohol is associated with decreases in reaction time and visual acuity, lowered levels of alertness, and reduction in behavioral control. With excessive alcohol use, a person might experience a complete loss of consciousness and/or difficulty remembering events that occurred during a period of intoxication (McKim & Hancock, 2013). In addition, if a pregnant woman consumes alcohol, her infant may be born with a cluster of birth defects and symptoms collectively called fetal alcohol spectrum disorder (FASD) or fetal alcohol syndrome (FAS).

With repeated use of many central nervous system depressants, such as alcohol, a person becomes physically dependent upon the substance and will exhibit signs of both tolerance and withdrawal. Psychological dependence on these drugs is also possible. Therefore, the abuse potential of central nervous system depressants is relatively high.

Drug withdrawal is usually an aversive experience, and it can be a life-threatening process in individuals who have a long history of very high doses of alcohol and/or barbiturates. This is of such concern that people who are trying to overcome addiction to these substances should only do so under medical supervision.

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Stimulants

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Learning Objectives

  • Identify stimulants and describe how they affect the brain and body

Stimulants are drugs that tend to increase overall levels of neural activity. Many of these drugs act as agonists of the dopamine neurotransmitter system. Dopamine activity is often associated with reward and craving; therefore, drugs that affect dopamine neurotransmission often have abuse liability. Drugs in this category include cocaine, amphetamines (including methamphetamine), cathinones (i.e., bath salts), MDMA (ecstasy), nicotine, and caffeine.

Cocaine can be taken in multiple ways. While many users snort cocaine, intravenous injection and ingestion are also common. The freebase version of cocaine, known as crack, is a potent, smokable version of the drug. Like many other stimulants, cocaine agonizes the dopamine neurotransmitter system by blocking the reuptake of dopamine in the neuronal synapse.

Dig Deeper: Crack Cocaine

Crack (Figure 1) is often considered to be more addictive than cocaine itself because it is smokable and reaches the brain very quickly. Crack is often less expensive than other forms of cocaine; therefore, it tends to be a more accessible drug for individuals from impoverished segments of society. During the 1980s, many drug laws were rewritten to punish crack users more severely than cocaine users. This led to discriminatory sentencing with low-income, inner-city minority populations receiving the harshest punishments. The wisdom of these laws has recently been called into question, especially given research that suggests crack may not be more addictive than other forms of cocaine, as previously thought (Haasen & Krausz, 2001; Reinerman, 2007).

A photograph shows crack rocks. A ruler indicates that each crack rock is approximately 1–2 inches wide.
Figure 1. Crack rocks like these are smoked to achieve a high. Compared with other routes of administration, smoking a drug allows it to enter the brain more rapidly, which can often enhance the user’s experience. (credit: modification of work by U.S. Department of Justice)

Amphetamines have a mechanism of action quite similar to cocaine in that they block the reuptake of dopamine in addition to stimulating its release (Figure 2). While amphetamines are often abused, they are also commonly prescribed to children diagnosed with attention deficit hyperactivity disorder (ADHD). It may seem counterintuitive that stimulant medications are prescribed to treat a disorder that involves hyperactivity, but the therapeutic effect comes from increases in neurotransmitter activity within certain areas of the brain associated with impulse control.

An illustration of a presynaptic cell and a postsynaptic cell shows these cells’ interactions with cocaine and dopamine molecules. The presynaptic cell contains two cylinder-shaped channels, one on each side near where it faces the postsynaptic cell. The postsynaptic cell contains several receptors, side-by-side across the area that faces the presynaptic cell. In the space between the two cells, there are both cocaine and dopamine molecules. One of the cocaine molecules attaches to one of the presynaptic cell’s channels. This cocaine molecule is labeled “bound cocaine.” An X-shape is shown over the top of the bound cocaine and the channel to indicate that the cocaine does not enter the presynaptic cell. A dopamine molecule is shown inside of the presynaptic cell’s other channel. Arrows connect this dopamine molecule to several others inside of the presynaptic cell. More arrows connect to more dopamine molecules, tracing their paths from the channel into the presynaptic cell, and out into the space between the presynaptic cell and the postsynaptic cell. Arrows extend from two of the dopamine molecules in this in-between space to the postsynaptic cell’s receptors. Only the dopamine molecules are shown binding to the postsynaptic cell’s receptors.
Figure 2. As one of their mechanisms of action, cocaine and amphetamines block the reuptake of dopamine from the synapse into the presynaptic cell.

In recent years, methamphetamine (meth) use has become increasingly widespread. Methamphetamine is a type of amphetamine that can be made from ingredients that are readily available (e.g., medications containing pseudoephedrine, a compound found in many over-the-counter cold and flu remedies). Despite recent changes in laws designed to make obtaining pseudoephedrine more difficult, methamphetamine continues to be an easily accessible and relatively inexpensive drug option (Shukla, Crump, & Chrisco, 2012).

The cocaine, amphetamine, cathinones, and MDMA users seek a euphoric high, feelings of intense elation and pleasure, especially in those users who take the drug via intravenous injection or smoking. Repeated use of these stimulants can have significant adverse consequences. Users can experience physical symptoms that include nausea, elevated blood pressure, and increased heart rate. In addition, these drugs can cause feelings of anxiety, hallucinations, and paranoia (Fiorentini et al., 2011). Normal brain functioning is altered after repeated use of these drugs. For example, repeated use can lead to overall depletion among the monoamine neurotransmitters (dopamine, norepinephrine, and serotonin). People may engage in compulsive use of these stimulant substances in part to try to reestablish normal levels of these neurotransmitters (Jayanthi & Ramamoorthy, 2005; Rothman, Blough, & Baumann, 2007).

Caffeine is another stimulant drug. While it is probably the most commonly used drug in the world, the potency of this particular drug pales in comparison to the other stimulant drugs described in this section. Generally, people use caffeine to maintain increased levels of alertness and arousal. Caffeine is found in many common medicines (such as weight loss drugs), beverages, foods, and even cosmetics (Herman & Herman, 2013). While caffeine may have some indirect effects on dopamine neurotransmission, its primary mechanism of action involves antagonizing adenosine activity (Porkka-Heiskanen, 2011).

While caffeine is generally considered a relatively safe drug, high blood levels of caffeine can result in insomnia, agitation, muscle twitching, nausea, irregular heartbeat, and even death (Reissig, Strain, & Griffiths, 2009; Wolt, Ganetsky, & Babu, 2012). In 2012, Kromann and Nielson reported on a case study of a 40-year-old woman who suffered significant ill effects from her use of caffeine. The woman used caffeine in the past to boost her mood and to provide energy, but over the course of several years, she increased her caffeine consumption to the point that she was consuming three liters of soda each day. Although she had been taking a prescription antidepressant, her symptoms of depression continued to worsen and she began to suffer physically, displaying significant warning signs of cardiovascular disease and diabetes. Upon admission to an outpatient clinic for treatment of mood disorders, she met all of the diagnostic criteria for substance dependence and was advised to dramatically limit her caffeine intake. Once she was able to limit her use to less than 12 ounces of soda a day, both her mental and physical health gradually improved. Despite the prevalence of caffeine use and the large number of people who confess to suffering from caffeine addiction, this was the first published description of soda dependence appearing in scientific literature.

Nicotine is highly addictive, and the use of tobacco products is associated with increased risks of heart disease, stroke, and a variety of cancers. Nicotine exerts its effects through its interaction with acetylcholine receptors. Acetylcholine functions as a neurotransmitter in motor neurons. In the central nervous system, it plays a role in arousal and reward mechanisms. Nicotine is most commonly used in the form of tobacco products like cigarettes or chewing tobacco; therefore, there is a tremendous interest in developing effective smoking cessation techniques. To date, people have used a variety of nicotine replacement therapies in addition to various psychotherapeutic options in an attempt to discontinue their use of tobacco products. In general, smoking cessation programs may be effective in the short term, but it is unclear whether these effects persist (Cropley, Theadom, Pravettoni, & Webb, 2008; Levitt, Shaw, Wong, & Kaczorowski, 2007; Smedslund, Fisher, Boles, & Lichtenstein, 2004).

Link to Learning

To learn more about some of the most commonly abused prescription and street drugs, check out the Commonly Abused Drugs Chart and the Commonly Abused Prescription Drugs Chart from the National Institute on Drug Abuse.

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Opioids

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Learning Objectives

  • Identify opioids and describe how they impact the brain and behavior

An opioid is one of a category of drugs that includes heroin, morphine, methadone, and codeine. Opioids have analgesic properties; that is, they decrease pain. Humans have an endogenous opioid neurotransmitter system—the body makes small quantities of opioid compounds that bind to opioid receptors reducing pain and producing euphoria. Thus, opioid drugs, which mimic this endogenous painkilling mechanism, have an extremely high potential for abuse. Natural opioids, called opiates, are derivatives of opium, which is a naturally occurring compound found in the poppy plant. There are now several synthetic versions of opiate drugs (correctly called opioids) that have very potent painkilling effects, and they are often abused. For example, the National Institutes of Drug Abuse has sponsored research that suggests the misuse and abuse of the prescription pain killers hydrocodone and oxycodone are significant public health concerns (Maxwell, 2006). In 2013, the U.S. Food and Drug Administration recommended tighter controls on their medical use.

Historically, heroin has been a major opioid drug of abuse (Figure 1). Heroin can be snorted, smoked, or injected intravenously. Like the stimulants described earlier, the use of heroin is associated with an initial feeling of euphoria followed by periods of agitation. Because heroin is often administered via intravenous injection, users often bear needle track marks on their arms and, like all abusers of intravenous drugs, have an increased risk for contraction of both tuberculosis and HIV.
Photograph A shows various paraphernalia spread out on a black surface. The items include a tourniquet, three syringes of varying widths, three cotton-balls, a tiny cooking vessel, a condom, a capsule of sterile water, and an alcohol swab. Photograph B shows a hand holding a spoon containing heroin tar above a small candle.
Figure 1. (a) Common paraphernalia for heroin preparation and use are shown here in a needle exchange kit. (b) Heroin is cooked on a spoon over a candle. (credit a: modification of work by Todd Huffman)

Aside from their utility as analgesic drugs, opioid-like compounds are often found in cough suppressants, anti-nausea, and anti-diarrhea medications. Given that withdrawal from a drug often involves an experience opposite to the effect of the drug, it should be no surprise that opioid withdrawal resembles a severe case of the flu. While opioid withdrawal can be extremely unpleasant, it is not life-threatening (Julien, 2005). Still, people experiencing opioid withdrawal may be given methadone to make withdrawal from the drug less difficult. Methadone is a synthetic opioid that is less euphorigenic than heroin and similar drugs. Methadone clinics help people who previously struggled with opioid addiction manage withdrawal symptoms through the use of methadone. Other drugs, including the opioid buprenorphine, have also been used to alleviate symptoms of opiate withdrawal.

Codeine is an opioid with relatively low potency. It is often prescribed for minor pain, and it is available over-the-counter in some other countries. Like all opioids, codeine does have abuse potential. In fact, abuse of prescription opioid medications is becoming a major concern worldwide (Aquina, Marques-Baptista, Bridgeman, & Merlin, 2009; Casati, Sedefov, & Pfeiffer-Gerschel, 2012).

The Opioid Epidemic

The opioid epidemic, or the opioid crisis, refers to the extensive overuse of opioid drugs, both from medical prescriptions and from illegal sources. The epidemic began slowly in the United States, beginning in the late 1990s, and led to a massive increase in opioid use in recent years, contributing to over 70,000 drug overdose deaths in the U.S. in 2018. Fentanyl alone, being 50 times stronger than heroin and 100 times stronger than morphine, was causing about 200 overdose deaths per day in 2017.Fentanyl As A Dark Web Profit Center, From Chinese Labs To U.S. Streets", KUAR, NPR Radio News, Sept. 4, 2019

Opioids are a diverse class of moderately strong, addictive, inexpensive painkillers prescribed by doctors. In the late 1990s, pharmaceutical companies reassured the medical community that patients would not become addicted to opioid pain relievers and healthcare providers began to prescribe them at greater rates. This led to widespread misuse of both prescription and non-prescription opioids before it became clear that these medications could indeed be highly addictive.

Though aggressive opioid prescription practices played the biggest role in creating the epidemic, the popularity of illegal substances such as potent heroin and illicit fentanyl have become an increasingly large factor. It has been suggested that decreased supply of prescription opioids caused by opioid prescribing reforms turned people who were already addicted to opioids towards illegal substances.Prescription Opioid Data". Centers for Disease Control and Prevention (CDC). Retrieved November 2, 2018.

In 2015, approximately 50% of drug overdoses we