Predictably Irrational: The Hidden Forces That Shape Our Decisions

by Dan Ariely

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 bad. But how deep are these influences? Do they just change our beliefs, or do they also change the physiology of the experience itself? In other words, can previous knowledge actually modify the neural activity underlying the taste itself, so that when we expect something to taste good (or bad), it will actually taste that way? To test this possibility, Leonard,

The significance of this question is that if knowledge merely informs us of a state of affairs, then it shouldn’t matter whether our participants received the information before or after tasting the beer: in other words, if we told them up front that there was vinegar in the beer, this should affect their review of the beer. And if we told them afterward, that should similarly affect their review. After all, they both got the same bad news about the vinegar-laced beer. This is what we should expect if knowledge merely informs us. On