Abstract: Social identity complexity is one recent focus of social psychology, which refers to the way in which individuals subjectively represent the relationships among their multiple ingroup memberships. Social identity complexity reflects the degree of overlap perceived to exist between groups of which a person is simultaneously a member. When the overlap of multiple ingroups is perceived to be high, social identity complexity is low. Conversely, when the overlap of multiple ingroups is perceived to be low, social identity complexity is high. After a brief introduction of multiple ingroups representation model, this article systematically reviewed the researches on the contents and methods of social identity complexity, as well as the antecedents and consequences of social identity complexity. Finally, future studies should strive to forward theory and research design, validity verification of scales and the application of results.

Key words: social identity complexity, multiple social identities, overlap, ingroup bias, outgroup tolerance