An influential concept in the study of the relationship between attitudes and behavior.

First proposed by Leon Festinger in 1957, the theory of cognitive dissonance is based on the principle that people prefer their cognitions, or beliefs, to be consistent with each other and with their own behavior.

Inconsistency, or dissonance, among their own ideas makes people uneasy enough to alter these ideas so that they will agree with each other. For example, smokers forced to deal with the opposing thoughts "I smoke" and "smoking is dangerous" are likely to alter one of them by deciding to quit smoking. Alternatively, one can diffuse dissonance by reducing its importance (discounting the evidence against smoking or adopting the view that smoking will not harm you personally); adding new information that gives more weight to...