In psychology, cognitive dissonance is an uncomfortable feeling or stress caused by holding two contradictory ideas simultaneously. The theory of cognitive dissonance proposes that people have a fundamental cognitive drive to reduce this dissonance by modifying an existing belief, or rejecting one of the contradictory ideas.
Often one of the ideas is a fundamental element of ego, like "I am a good person" or "I made the right decision." This can result in rationalization when a person is presented with evidence of a bad choice, or in other cases. Prevention of cognitive dissonance may also contribute to confirmation bias or denial of discomforting evidence. If not corrected, this can lead to further bad choices for the sake of consistency, rather than learning from mistakes.
Experiments have attempted to quantify this cognitive drive. Studies have not so far detected any gender or cross-cultural differences.