Predictably Irrational: The Hidden Forces That Shape our Decisions

Chapter 10 looks at “how previously held impressions can cloud our point of view” (201). Alongside colleagues, Ariely designed an experiment to see whether individuals’ expectations for a certain kind of beer would influence their taste perception. The experiment included two kinds of beer: One was an unaltered beer (either Budweiser or Sam Adams), and the other included drops of balsamic (known as MIT brew).

There were two phases of the experiment. In the first phase, the researchers offered the bar patrons free samples of two beers. The students then selected the beer they wanted as a full glass. In the second phase, they provided the students with more details about the beers, including that the second contained balsamic vinegar. Ariely found that without foreknowledge about the vinegar, most students chose the second, vinegar-tinged beer for their full glass. However, when they knew about this ingredient, participants chose the unaltered beer. Ariely tried a similar experiment with coffee and had the same results.

These results suggest that “when we believe beforehand that something will be good, therefore, it generally will be good—and when we think it will be bad, it will be bad” (204-05). Ariely wanted to see whether previous expectations altered neural activity underlying taste.