In-group favoritism, sometimes known as in-group–out-group bias, in-group bias, intergroup bias, or in-group preference, is a pattern of favoring members of one's in-group over out-group members. This can be expressed in evaluation of others, in allocation of resources, and in many other ways.[1][2]

This effect has been researched by many psychologists and linked to many theories related to group conflict and prejudice. The phenomenon is primarily viewed from a social psychology standpoint. Studies have shown that in-group favoritism arises as a result of the formation of cultural groups.[3][4] These cultural groups can be divided based on seemingly trivial observable traits, but with time, populations grow to associate certain traits with certain behavior, increasing covariation. This then incentivizes in-group bias.

Two prominent theoretical approaches to the phenomenon of in-group favoritism are realistic conflict theory and social identity theory. Realistic conflict theory proposes that intergroup competition, and sometimes intergroup conflict, arises when two groups have opposing claims to scarce resources. In contrast, social identity theory posits a psychological drive for positively distinct social identities as the general root cause of in-group favoring behavior.

Oops something went wrong: