A belief that members of a group share particular traits, applied generally and often without regard to individual variation, is a stereotype. Stereotypes can be positive or negative, accurate in base-rate terms or wholly inaccurate.

They arise from limited experience, social learning, and the cognitive need to simplify a complex social world. Once formed, stereotypes guide attention, interpretation, and memory in ways that confirm them. They can be activated automatically and influence behavior even when the person consciously rejects them.

Stereotype threat shows how awareness of a negative stereotype about one’s group can impair performance. Reducing the impact of stereotypes involves individuation, intergroup contact, and changes in social norms. Stereotypes are cognitive tools that become social problems when they harden into prejudice and discrimination.

The efficiency of a stereotype is also the source of its unfairness.