As the holiday season approaches, many people are going to enter it with a diet in place. Then, with the introduction of a single slice of pie, that diet will be shot. We will demur at first, citing calories and healthy living, but then we will have a bite, then another, and then before we know it, that diet has fallen by the wayside.

Research indicates that we do get rewarded for throwing away our winter weight goals, even if our waistlines may not feel the same way. That piece of pie tastes even more delicious if we indulge than it would otherwise. Of course, that is something that we have all experienced - but science indicates that it is true.

In a study published in The Journal of Marketing Research, researchers from Northwestern University said, "People who are primed with guilt subsequently experience greater pleasure than people who are not. People lack awareness of this automatic process."

The study consisted of six different experiments. In the first, the researchers split 40 participants into two groups. Both viewed six magazine covers. Half the group was forced to look at four of those six magazine covers that were health-related; the other half looked at covers that were completely unrelated.

Then the 40 participants were given chocolate candy bars for what they were told was a "taste study". The participants who had been reading about healthy eating - and therefore presumably felt guilty about indulging - reported that the chocolate bar tasted significantly better than the other group.

A second experiment asked 108 undergraduate students to describe three experiences in a few sentences. A third were asked to describe times that they felt guilty, a third were asked to describe times that they felt disgusted, and a final third were asked to describe three random times. Then all the students were given a chocolate truffle to sample. The students who relived their guiltiest moments reported that the chocolate truffle tasted better than the other groups.

A third experiment revealed that the relationship between guilt and pleasure existed even if participants were not being rewarded with food. The third experiment primed some of 64 female participants with guilt before letting them look at the online profiles of potential mates. The women who had felt guilty prior to looking at men derived much more pleasure from the experience.

Study authors, led by Kelly Goldsmith, say that the media has helped to reinforce the notion of guilt and pleasure. The findings could have import for public health campaigns. For example, campaigns that seek to get smokers to feel guilt may enhance the pleasure that a person feels when smoking a cigarette - and therefore make them less likely to quit.

The study proves that guilt is not an unnecessary emotion - just a counterproductive one. So have that slice of pie during the holidays and don't feel bad about it. Chances are, if you are ambivalent about it, you will not even need to eat the whole slice.