cognitive dissonance

Meaning: Proposed by Leon Festinger, cognitive dissonance is an unpleasant tension that arises when a person's cognitions (beliefs, attitudes, or knowledge of their own behavior) conflict. Because the tension is aversive, people are motivated to reduce it: by changing the attitude, changing the behavior, adding a justifying thought, or downplaying the conflict. It is typically stronger when the action was freely chosen and matters to self-image.

On the MCAT: The classic study is Festinger and Carlsmith. Participants did a dull task, then were paid $1 or $20 to tell the next person it was fun. Those paid $1 later rated the task as more enjoyable. The $20 gave enough external justification, so there was little dissonance; the $1 left insufficient justification, so the attitude shifted. Expect vignettes that ask you to predict which condition changes attitude more, or to name how a person reduced dissonance.

Common confusion: Students often expect a bigger reward to produce more attitude change. The opposite is typical: less external justification means more dissonance and more change. Also, dissonance is the tension itself, not the attitude change that resolves it.