Thinking and Intelligence
- Explain some common roadblocks to effective problem solving, including choice blindness
Some choices are easy (“Do you want pepperoni or anchovies on your pizza?”) and some choices are hard (“Are you going to get Amazon Echo or Google Home?”), but most of us like to think that we “know our own mind”—that is, when we finally make a choice, we are clear about our decision. Research by psychologists in Sweden shows that this confidence in our own self-knowledge may not always be justified.
Choice blindness is the failure to recall a choice immediately after we have made that choice. If you go to an ice cream store, order a chocolate cone, and then accept a strawberry cone without noticing, that is choice blindness. If you go to an electronics store, select the new 55-inch Vizio television, and then fail to notice when they bring out (and expect you to pay for) the far more expensive 55-inch Sony television, that is choice blindness. If you order a burger and fries, and then don’t notice when soup-and-salad is placed in front of you, that is choice blindness.
As you have seen, Johannson, Hall, and their colleagues found a method for inducing choice blindness in a laboratory setting, but they wanted to do more than simply demonstrate that people sometimes forget their choices. As psychological scientists, their goal is to explore an interesting phenomenon (i.e., choice blindness) to understand why it happens and to see if it tells us anything new about the way our minds work.
The Attraction Preference Experiment
You can learn the basics of the experiment conducted by Petter Johannson, Lars Hall and their colleagues by watching the following video.
Johannson and Hall were curious to see how often people noticed that there was a mismatch between their choice and the picture they were told they had chosen. Here’s how the experiment worked. Imagine that you are sitting across a table from an experimenter, who is dressed in a long sleeved black shirt. He shows you a pair of pictures of head-and-shoulder shots of two males or two females. On each trial, you indicate which of the two people in the pictures you find more attractive. After you make your choice, the experimenter hands you the card you just pointed at and asks you to explain why you preferred this person.
Except that this didn’t always happen this way. Using a magician’s trick, on some trials, when the experimenter handed you the card, he actually handed you the card you did NOT choose.
Watch this video to see the experimenters explain it.
The researchers tested 120 college students (70 female, 50 male). The pictures were all of women. As the video showed, they made their choice and then immediately explained the reasons for their preference. Only 13% of the switches were detected immediately. Approximately 10% more switches were mentioned “retrospectively”, where a participant initially justified choosing the switched face, but later indicated some suspicion that the wrong picture had been presented. Most participants who detected a switch attributed it to a technical error rather than suspecting that it was part of the research procedure.
But is it Real? The Value of Replication
The video you just watched described an experiment with a surprising result: more than 75% of the time, people make a choice and then, without indicating that anything is amiss, they proceed to justify a choice they did not make. But how solid is this study and how much can we believe these results? Maybe the choice blindness experiment reported real results, but (even assuming that the experimenters were completely honest and careful) could this have just been a weird outcome that will never happen again? In other words, is this a reliable result or just a fluke?
There is only one way to determine if a phenomenon is reliable, and that is replication. If you can’t replicate an effect, then you shouldn’t waste people’s time reading about it in a scientific paper.
There are at least three different types of replication.
- Direct Replication: Conduct exactly the same study again, usually with new participants from the same population as the original study. A successful replication would produce results similar to those in the original study.
- Systematic Replication: Conduct a study that is similar to the original one, but using slightly different methods or stimuli.
- Conceptual Replication: Conduct a very different study that still tests the original idea. In the current context, a conceptual replication would test the choice blindness idea using a method that did not involve choosing attractive people.
So, can you believe the choice blindness phenomenon?
In the years just before they published their 2005 study, the experimenters conducted two similar studies. For these studies, the pictures were presented on a computer screen, and the computer switched the pictures on the critical trials, so no magic was necessary. The results were very similar to the results of the study reported in the video above.
When the BBC (British Broadcasting Corporation) made the video, they reconstructed the experiment in a form very similar to the original. They reported that 80% of the participants did not notice any switching of pictures—a result very similar to the original. Unfortunately, without a published report of the study, it is impossible to know if the scientific standards of the original study had been maintained.
In 2014, researchers at the National University of Singapore reported a study similar to the experiment shown in the video. The stimuli were presented using a computer rather than a live experimenter. In addition to choosing one of the two faces, the participants rated their confidence in their choice and they typed their explanation of their preference. The faces were all of Caucasian women (as in the original study), but the participants were all of Asian descent (ethnic backgrounds: Chinese, Indian, and Vietnamese). Their results were similar to those of the original study.
Here is video showing another study by Johannson and Hall. The video has no sound—only subtitles.
Before an election, researchers polled people about their political preferences, selecting either right-wing or left-wing policies. The researchers secretly copied down the opposite of their responses and had the participants explain their answers. Fascinatingly, many people defended the views they said to have disagreed with.
Link to Learning
Visit this link to watch another video related about conceptual replication, this time related to taste.
From Phenomenon to Scientific Exploration
What you saw in the video is what a scientist would call a phenomenon—that is, a behavior that happens under certain conditions. The video showed that, if an experimenter is tricky enough, he or she can get people to justify choices that they never made. If you find this phenomenon interesting, then it may be worth your time to try to find out why it happens. (If you didn’t think it was interesting, then you will probably move on to find something that inspires you.)
Any of the choices in the list above could explain—fully or in part—the choice blindness phenomenon, but each idea would need to be tested. That is where the science comes in. The starting point for science is something interesting (a surprising phenomenon). If we are motivated to ask why something happened, then we jump into the real work of science: exploring possible explanations.
The next scientific step systematically (i.e., carefully and with specific purposes) changes elements of the procedures or stimuli to see how these changes affect the results. Remember that our dependent variable is the probability that the change in faces will be detected. So now we try to learn more about change blindness by seeing how changing specific details (independent variables) either increase or decrease people’s likelihood of noticing the switch in faces.
Two Variables: Time and Similarity
In the 2005 study, Johansson and Hall looked at two interesting variables that might influence detection of the mismatch. First, how rushed were the participants to make their decision? They gave some people only 2 seconds to choose the more attractive person. Others were given 5 seconds, and another group was given as long as people wanted (free choice). Should more time make someone more likely or less likely to notice that they have been given the picture they did not choose?
The second variable was how similar the two faces were to one another. In some cases, the two faces were similar to each other in general features, while in other cases the two faces were more distinctly different. If the two faces are quite different, how should that affect your ability to notice?
If we put the two manipulated variables (time and similarity) together, that gives us six conditions:
In the figure below, adjust the bars to fit your predictions about how often people would notice the picture switch. Higher bars mean people more often noticed that the cards had been switched. Lower bars mean that people made one choice and didn’t notice when they were given the wrong picture. This isn’t easy because you need to take account of the two variables: (1) amount of time looking at the pictures before your choice and (2) similarity of the faces in the pictures.
Click here to see the what most people expect the results to be.
Most people make predictions that put the red bars lowest, the purple bars in the middle, and the green bars highest. This supports the idea that the more time you have to look at the pictures, the more likely you are to notice that the picture you have chosen is not the one the experimenter gave you.
People also expect that the switch will be more noticeable if the faces are dissimilar. For example, if we look at the green bars with unlimited time, it makes sense that people will generally notice when the faces have been switched on them, and this is much greater when the two faces are very different (dissimilar condition) than when they are similar (similar condition).
Most people find it hard to believe that lots of people will be tricked by the switch in faces, even if the experimenter has good magician skills. So, what did happen?
HERE are the actual results from the study.
First, people generally did not notice the change in faces. Overall, participants on fewer than 20% of the trials noticed any of the card switches. Most participants simply did not realize that the faces had been switched, and many were either very surprised when they were told what had happened or they simply didn’t believe the experimenters.
There was an effect of time. The red bars (2 seconds to choose) are lower than the purple bars (5 seconds to choose), and the purple bars are lower than the green bars (unlimited time to choose), but the differences are fairly modest. The bigger surprise was the LACK of difference between the similar and dissimilar faces. In all three time conditions, there was no significant difference—barely a measurable difference–between the similar and dissimilar faces conditions.
What Do These Results Tell Us?
With just these results, we are still a long way from understanding choice blindness. The experiment you just read takes us a couple of steps in the right direction. First, the similarity of the faces is (surprisingly) not a particularly influential factor. This does not mean that the case is closed and similarity is unimportant, but it does suggest that confusion due to similarity may not be the whole story.
The amount of time participants had to choose did have a big influence on detection of a switch in faces. When the participants were rushed (2 second condition), the chance of detecting a change was very slight. Given 5 seconds, detection improved, but not by a great amount. Unlimited time to choose made a substantial difference, but detection was still only around 25%. These results suggest that time to choose may be an important factor, but it is not the whole story. Furthermore, we are still not sure what it was about the extra time that led to improved detection. Did more time allow the participants to remember the faces better? Or perhaps their memory for faces was not improved, but they had more time to think of reasons they preferred one person over the other (her earrings, the way her hair flowed, a look in her eyes). These preferred features could signal to them that something was missing when the wrong picture was presented.
If you explore the research literature on choice blindness, you will find that the phenomenon has been studied from many angles. Experiments have been conducted in university laboratories and on the streets of a city in the Netherlands. Choice blindness in the video involved remembering what someone looked like, but choices involving sound, taste, and smell have also produced choice blindness. Even people’s judgments about their own personality and preferences is open to choice blindness. We don’t fully understand when and why choice blindness occurs, but it is an intriguing phenomenon, open to scientific curiosity.
A Final Thought
In a TED talk from 2016, Petter Johannson describes choice blindness to an audience. At the end he acknowledges that choice blindness can make people look silly or worse, but he also believes that this research provides us with an insight about people that may be reason for hope in a world seemingly full of discord and bereft of compromise.
Here are the closing lines from his TED talk:
This [choice blindness] may all seem a bit disturbing. But if you want to look at it from a positive direction, it could be seen as showing: Okay, so we’re all a little bit more flexible than we think. We can change our minds. Our attitudes are not set in stone. And we can also change the minds of others if we can only get them to engage with the issue and see it from the opposite view. … Getting rid of the need to stay consistent is actually a huge relief and makes [social] life so much easier to live.
So the conclusion must be, “Know that you don’t know yourself. Or at least not as well as you think you do.”
Licenses and Attributions (Click to expand)
CC licensed content, Original
- Psychology in Real Life: Choice Blindness. Authored by: Patrick Carroll for Lumen Learning. License: CC BY: Attribution
CC licensed content, Shared previously
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All rights reserved content
- BBC Choice Blindness. Authored by: BBC. Provided by: ChoiceBlindnessLab. Located at: https://www.youtube.com/watch?v=wRqyw-EwgTk. License: Other. License Terms: Standard YouTube License
- Using Choice Blindness to Shift Political Attitudes and Voter Intentions. Provided by: ChoiceBlindnessLab. Located at: https://www.youtube.com/watch?v=_htNx0eWmgs. License: Other. License Terms: Standard YouTube License
- Petter Johannson, Lars Hall, Sverker Sikström, & Andreas Olsson. (2005). Failure to detect mismatches between intention and outcome in a simple decision task. Science, 310 (7 October 2005), 116-119. ↵
- The video is a segment from a BBC video from the science series called Horizons. This particular show was about decision making ↵
- The results are more complex than the figure suggests. The data shown above are limited to first detections of the switch in pictures. After people notice that there has been a switch, they tend to be a bit suspicious and they are more vigilant about noticing changes. If all trials are taken into account, the data are still similar to these, but not quite as pretty. See the original paper for all the details. ↵