19.5: Post-Decisional Dissonance

The third sort of dissonance phenomena involves decision making. We often must make difficult choices between alternatives: Where should I go to college? What should I major in? Which job offer should I accept? Should I marry Wanda? Should we put off having children until we are more settled?

In a difficult decision, each alternative has some pluses and some minuses, and we aren’t sure how to balance them out in a way that will lead to the best choice. You are trying to decide whether to bring the collie or the terrier home from the animal shelter. Both dogs have pluses and minuses. The collie seems smarter, but she may be too big for your little apartment; the terrier is cute but seems a little dumb and you’ve heard terriers are difficult to house train.

Whichever dog you choose, you will give up some positive features (of the dog you don’t take) and accept some negative features (of the dog that you do take). Your awareness of these positive and negative features will be dissonant with the choice that you eventually make. This is known as post-decisional dissonance: after a difficult choice, we are likely to experience dissonance.

Post-decisional dissonance is greater when the choice is hard to undo, because we can’t reduce the dissonance by changing our decision. In such cases, how could we reduce it? Once people commit themselves to a choice, they often exaggerate both the positive aspects the thing they chose and the negative aspects of the thing they rejected. Once you chose the terrier, you may conclude that a collie would have been too much trouble, probably wouldn’t have been affectionate, and that terriers are much smarter than you had supposed.

This strategy for reducing post-decisional dissonance shows up in many studies. Jack Brehm posed as a representative of a company that was doing consumer research on household products. He asked people to rate the desirability of various household appliances, like coffee makers and toasters. As a reward for participating in the study, each woman was offered a choice between two of the items that she had rated. Later, the women were asked to re-rate the desirability of the products. Brehm found that the appliance the woman had chosen was rated higher than it originally had been, while the appliance she could have chosen, but didn’t, was ranked much lower. This is known as the spreading effect; we often feel like there is a greater difference between the desirability of things after we choose between them than we did beforehand.

Although the evidence is less clear cut, some of it suggests that after a difficult decision people also often become selective in the information they seek about the things they chose between. They seek out and attend to information that supports their decision (after bringing home his terrier, Wilbur, reads about the virtues of terriers) and avoid or discount information that doesn’t support it (he quits reading about the strong points of collies).