Cognitive Dissonance

Cognitive dissonance is a discomfort caused by holding conflicting ideas simultaneously. The theory of cognitive dissonance proposes that people have a motivational drive to reduce dissonance. They do this by changing their attitudes, beliefs, and actions.[1] Dissonance is also reduced by justifying, blaming, and denying. The phrase was coined by Leon Festinger in his 1956 book When Prophecy Fails, which chronicled the followers of a UFO cult as reality clashed with their fervent beliefs.[2][3] It is one of the most influential and extensively studied theories in social psychology. A closely related term, cognitive disequilibrium, was coined by Jean Piaget to refer to the experience of a discrepancy between something new and something already known or believed.
Experience can clash with expectations, as, for example, with buyer's remorse following the purchase of an expensive item. In a state of dissonance, people may feel surprise,[1] dread, guilt, anger, or embarrassment. People are biased to think of their choices as correct, despite any contrary evidence. This bias gives dissonance theory its predictive power, shedding light on otherwise puzzling irrational and destructive behavior.
http://en.wikipedia.org/wiki/Cognitive_dissonance
Experience can clash with expectations, as, for example, with buyer's remorse following the purchase of an expensive item. In a state of dissonance, people may feel surprise,[1] dread, guilt, anger, or embarrassment. People are biased to think of their choices as correct, despite any contrary evidence. This bias gives dissonance theory its predictive power, shedding light on otherwise puzzling irrational and destructive behavior.
http://en.wikipedia.org/wiki/Cognitive_dissonance