BOSTON–How horrifying might it be to lose a limb? How exhilarating might it be to find true love? When these things actually happen, reality rarely matches our predictions. At the annual meeting of the American Association for the Advancement of Science (ScienceNOW's publisher) today, psychologist Daniel Gilbert of Harvard University presented new experimental results that may explain why.
Gilbert suspects that anticipation may play a key role in the disconnect between fact and forecast. When people have lots of time to think, he said, they may consider alternatives that cast the expected experience in a favorable or jaundiced light. Imagine you just took a test, for example, and didn't feel good about it. You might anticipate getting a C or a D grade; and in that case, you'd think you'd feel great if you actually got a B. But when you get your test back and do get that B, the grade doesn't seem as great as you thought it would. That's because, according to Gilbert's theory, your brain is so busy processing the moment that the earlier comparisons disappear.
To test the hypothesis, Gilbert's team--led by graduate student Carey Morewedge--recruited Harvard undergraduates to eat potato chips. Some 60 students were divided into two groups: predictors and experiencers. Both groups were presented two trays, one with potato chips and the other with either a chocolate bar or a can of sardines. Predictors presented with chocolate said they'd only like the potato chips a little bit, whereas predictors faced with sardines said they'd love the chips. But the experiencers, who actually ate the chips, liked them the same, regardless of whether chocolate or sardines were offered as an alternative. All predictions aside, "when you put the potato chips in your mouth, the thing on the other side … is wildly irrelevant," Gilbert said at the meeting.
In a final experiment, the team told the chip eaters to slow down their munching. That ostensibly gave them more time to think about their alternatives. And indeed, when experiencers could only eat one chip every 45 seconds, they rated the chips much as the predictors had. Given time to think about it, chips were better when they saved you from sardines, said Gilbert, but not nearly as tasty when they kept you from the chocolate.
The findings support the idea that predictions of how we will feel about a given experience depend on the alternatives, Gilbert said. "I don't really care about the act of potato chip eating. … This is a metaphor for mistakes people make in everyday life."
Randy Buckner, a neuroscientist at Harvard, says the chip research is about more than just why people make bad decisions. It gives us a window into how the brain processes memory and imagination. "Just as optical illusions have taught us so much about how the visual system works and what signals it uses," he says, "the errors people make tell us about the rules being used."
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