In 1972, Bem proposed the self-perception theory of attitude change, which proposes a different mechanism of change than that of Leon Festinger's cognitive dissonance theory. Although the two theories appear contradictory, evidence suggests that dissonance theory and self-perception theory each explain different aspects of how people adjust their attitudes and behaviors to one another. Dissonance theory explains how people change their attitudes when they find themselves acting in opposition to the attitudes they already hold, while self-perception theory explains how people create their attitudes in the first place.