This comes from the Association for Psychological Science.
October 4, 2010
It has been proven that after you make a choice, you adjust your opinion to think better of the option you chose. Now a study published in Psychological Science has found that this is true even if you don’t know the options that you’re choosing between.
Think about choosing Rome or Paris for a vacation. When first starting to decide, you may rate them about the same. But after choosing one as your destination, you’re likely to say that you prefer that city. This is thought to be a way to reduce the psychological tension created by rejecting one perfectly reasonable alternative and picking another one. Recently, critics have pointed out a flaw in this experimental design: you might actually have already liked Paris more than Rome, but for some reason this preference didn’t show up when you were asked to rate them.
Tali Sharot and coauthors set out to improve on the experimental design. One group of volunteers was asked to rate a list of vacation destinations, and then choose between pairs of places. The participants were then told they were taking part in a subliminal decision making test where they had to choose between the names of two vacation destinations that were flashed on a screen, side by side for two milliseconds. However, what actually flashed on the screen was nonsense strings (such as “%^!x *&()%), meaning the participants were making a completely blind choice. After the test was finished, they were told which place they’d “chosen” and were asked to rate the destinations again. Then as an additional control, a second group of volunteers rated vacation destinations that were chosen for them by a computer. Both groups had their vacation choices made for them, but only the second group knew that it was a computer generated choice.
The results show that preferences were altered after participants made a blind choice, but not after a computer dictated the decision. It turns out that just as preferences form choices, choices shape preferences.
“It’s a relief to know that psychologists are right about this basic principle,” says Tali Sharot. But “the effect is much smaller than what we usually see when we do non-blind choice.” This means that the critics were right to point out the flaw in the usual experimental design; people do have a preexisting preference, even if it’s not strong enough to show up in ratings.
Sharot, T., Velasquez, C.M., & Dolan, R.J. (2010). Do decisions shape preference?: Evidence from blind choice. Psychological science, 21. doi: 10.1177/0956797610379235