The evidence is pretty clear, though, that big positive and negative events don't have an enormous impact on people's . In a 1998 paper in the Journal of and Social Psychology, Dan Gilbert, Tim Wilson, and their colleagues found that college faculty being evaluated for tenure believed they would be quite unhappy if they were denied tenure. Several months after their tenure decision, though, college faculty who had been denied tenure were no less happy than those who had gotten tenure.

This finding, that we believe future positive and negative events have a bigger impact on our future happiness than they do, is called an error. One thing about these errors that is not well understood: Why don't they go away over time? We all have experience with these errors. As a kid, I remember toys that I really wanted because I had seen them in a catalog. When I actually got one of those toys, though, it was never quite the life-changing experience I expected. So, why don't examples like this get rid of affective forecasting errors?

This question was explored in a November 2010 paper in the Journal of Experimental Psychology by Tom Meyvis, Rebecca Ratner, and Jonathan Levav.

These researchers find that people have difficulty remembering their initial prediction for how they would feel after a positive or negative event. In one study, they asked voters in the 2008 election how they would feel a week after the election if Barack Obama won. Supporters of John McCain rated that they would be quite unhappy. A week after the election, these same voters were contacted again and asked how happy they were. They were also asked to recall how happy they said they would be before the election. These voters were significantly happier than they predicted they would be (that is the affective forecasting error). They also remembered their prediction as being less extreme than it was. That is, they did not remember predicting that they would be very unhappy.

The researchers demonstrated that this poor for previous predictions makes it hard for people to learn to predict better in the future. In this study, some people were reminded of their initial prediction, and those people who were reminded of what they actually predicted showed smaller affective forecasting errors in the future.

People came back for a second session, and actually ate sequences of jellybeans and rated their enjoyment. As it turns out, preference for jellybeans isn't affected at all by the one you just ate, and so there was an affected forecasting error. The participants were able to look at their ratings and see that they enjoyed the jellybean equally well regardless of what else they ate. One group of participants was then shown their original prediction (which showed that they expected a difference in enjoyment). The other group was not reminded of their original prediction.

Then, everyone did a similar task. They ranked a series of ice cream flavors. Then, they were asked how much they would enjoy eating a flavor they like moderately well either after having a spoonful of an ice cream they really enjoy or after having a spoonful they do not like at all. Obviously, this judgment is quite similar to the one about the jellybeans.

Those people who were reminded of their original judgment with the jellybeans correctly predicted that their enjoyment of ice cream would not be affected much by what they had eaten before. Those who were not reminded of their earlier judgment predicted that their enjoyment of the ice cream would be influenced by the flavor they ate before. So, those people who were not given a reminder still showed an affective forecasting error.

Overall, then, it seems like we continue to wrongly predict how events will affect our future happiness because we have difficulty remembering the predictions we make.

Do these affective forecasting errors really matter? In fact, these errors may be both a blessing and a curse.

On the positive side, it can be motivating to be very concerned about a future event. College faculty approaching tenure are often quite productive in the years before their evaluation, because they believe that the outcome of this decision will hugely influence their career. Even though the actual tenure decision won't influence their future happiness much, this hard work may still lay important groundwork for their research in years to come.

On the negative side, though, these affective forecasting errors can also lead to bad decisions. If you really believe that a sports car will make you happier, you may overpay to own it. That means that you will spend a lot of money on a purchase that ultimately won't affect your happiness that much.

On balance, then, it is probably best to remember that there are lots of factors that affect how happy you will be in the future, and that no single event will have that big an influence on that happiness.

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