what is cognitive dissonance

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. The occurrence of cognitive dissonance is consequence of a person’s performing an action that contradicts personal beliefs, ideals, and values; and also occurs when confronted with new information that contradicts said beliefs, ideals, and values

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. That a person who experiences internal inconsistency tends to become psychologically uncomfortable, and so is motivated to reduce the cognitive dissonance: either by changing parts of the cognition, to justify the stressful behavior; or by adding new parts to the cognition that causes the psychological dissonance; and by actively avoiding social situations and contradictory information that are likely to increase the magnitude of the cognitive dissonance