The more costly a decision in terms of time, money, effort, or inconvenience and the more irrevocable its consequences, the greater the dissonance and the greater the need to reduce it by overemphasizing the good things about the choice made. Therefore, when you are about to make a big purchase or an important decision—which car or computer to buy, whether to undergo plastic surgery, or whether to sign up for a costly self-help program—don’t ask someone who has just done it. That person will be highly motivated to convince you that it is the right thing to do.
