The cognitive dissonance theory (Festinger, 1957) is a general theoretical framework which explains how people change their opinions or hypotheses about themselves and their environment. An important application of cognitive dissonance theory is research on attitude change.
The basic assumption of cognitive dissonance theory is that people are motivated to reduce inconsistent cognitions. Cognition refers to any kind of knowledge or opinion about oneself or the world.

Two cognitions can be either relevant or irrelevant. If they are relevant, then they must be consonant or dissonant (i.e. that one does not follow from the other). Dissonant cognitions produce an aversive state which the individual will try to reduce by changing one or both of the cognitions. If, for example, a heavy smoker is exposed to statistics showing that smoking leads to lung cancer, he or she can change the cognition about how much he smokes ("I´m really only a light smoker.") or perceive the statistical data as hysterical environmentalist propaganda and discount it.

Cognitive dissonance can be reduced by adding new cognitions, if (a) the new cognitions add weight to one side and thus, decreases the proportion of cognitive elements that are dissonant or (b) the new cognitions change the importance of the cognitive elements that are in dissonant relation with one another. The other way to reduce cognitive dissonance is to change existing cognitions. Changing existing cognitions reduces dissonance if (a) the new content makes them less contradictory to others or (b) their importance is reduced.

If new cognitions cannot be added or the existing ones changed, behaviors that have cognitive consequences favoring consonance will be recruited. Seeking new information is an example of such behavior.

See also: attitude

Literature: Festinger (1957), Lindzey & Aronson (1985), pp. 70, 202

Entry by: Susanne Haberstroh

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