in social psychology, a theory that assumes that steady and unsteady states can be specified for cognitive units (e.g., a person and his or her attitudes or acts) and that such units tend to seek steady states (balance); e.g., balance exists when both parts of a unit are evaluated the same, but disequilibrium arises when both parts are not evaluated the same, which causes either cognitive reevaluation of the parts or their segregation.cognitive dissonance theory, consistency principle.