Cognitive dissonance (Festinger, 1957) refers to the mental discomfort felt when a person holds two or more contradictory beliefs, attitudes, or behaviors simultaneously. To reduce this discomfort, people typically change one of the conflicting cognitions, add new cognitions to justify the inconsistency, or minimize the importance of one belief. Classic example: a smoker who knows smoking is harmful must rationalize or reduce the dissonance somehow.