http://en.wikipedia.org/wiki/Cognitive_dissonance
Cognitive dissonance is a psychological state that describes the uncomfortable feeling between what one holds to be true and what one knows to be true
In simple terms, it can be the filtering of information that conflicts with what one already believes, in an effort to ignore that information and reinforce one's beliefs. In detailed terms, it is the perception of incompatibility between two cognitions, where "cognition" is defined as any element of knowledge, including attitude, emotion, belief, or behavior. The theory of cognitive dissonance states that contradicting cognitions serve as a driving force that compels the mind to acquire or invent new thoughts or beliefs, or to modify existing beliefs, so as to reduce the amount of dissonance (conflict) between cognitions.
Social psychologist Leon Festinger first proposed the theory in 1957 after the publication of his book When Prophecy Fails, observing the counterintuitive belief persistence of members of a UFO doomsday cult and their increased proselytization after the leader's prophecy failed. The failed message of earth's destruction, purportedly sent by aliens to a woman in 1956, became a disconfirmed expectancy that increased dissonance between cognitions, thereby causing most members of the impromptu cult to lessen the dissonance by accepting a new prophecy: that the aliens had instead spared the planet for their sake.
;~ )