In the field of psychology, cognitive dissonance is the mental discomfort (psychological stress) experienced by a person who simultaneously holds two or more contradictory beliefs, ideas, or values. This discomfort is triggered by a situation in which a person’s belief clashes with new evidence perceived by that person. When confronted with facts that contradict personal beliefs, ideals, and values, people will find a way to resolve the contradiction in order to reduce their discomfort.
In A Theory of Cognitive Dissonance (1957), Leon Festinger proposed that human beings strive for internal psychological consistency in order to mentally function in the real world. A person who experiences internal inconsistency tends to become psychologically uncomfortable, and so is motivated to reduce the cognitive dissonance, by making changes to justify the stressful behavior, either by adding new parts to the cognition causing the psychological dissonance, or by actively avoiding social situations and contradictory information likely to increase the magnitude of the cognitive dissonance.