Leon Festinger

Festinger used the term for psychological discomfort produced by inconsistent beliefs, actions, or evidence. His 1957 book A Theory of Cognitive Dissonance proposed that people are motivated to reduce that conflict by changing a belief, changing behavior, or rationalizing the inconsistency.

Participants performed a dull task and were then paid either $1 or $20 to tell another person that it was enjoyable. Those paid only $1 later rated the task more favorably, which the researchers interpreted as attitude change caused by insufficient external justification.

Festinger and his colleagues observed a small group that expected extraterrestrials to rescue them before a catastrophic flood. When the prediction failed, strongly committed members increased their efforts to recruit others, helping inspire the idea that social support can preserve a disconfirmed belief.

Festinger proposed in 1954 that people evaluate their opinions and abilities partly by comparing themselves with others. Comparisons are especially influential when no clear objective standard is available and the other person seems relevant or similar.