In-group favoritism, sometimes known as in-group–out-group bias, in-group bias, or intergroup bias, refers to a pattern of favoring members of one’s in-group over out-group members. This can be expressed in evaluation of others, allocation of resources, and many other ways. For example, it has been shown that people will seek to make more internal (dispositional) attributions for events that reflect positively on groups they belong to and more external (situational) attributions for events that reflect negatively on their groups.
This interaction 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. 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.
Ultimately, the in-group bias causes us to overestimate the abilities and value of our immediate group at the expense of people we don’t really know.