In-Group Bias

In-group bias is the tendency to favor members of one's own group over outsiders in evaluations, rewards, trust, and treatment. The idea has roots in William Graham Sumner's concept of ethnocentrism and his distinction between in-groups and out-groups. Muzafer Sherif's Robbers Cave experiment showed how competition produces hostility between groups, while Henri Tajfel's minimal group experiments found that even arbitrary categories generate favoritism. Tajfel and John Turner's social identity theory explained this as a way of gaining positive self-esteem through group membership. Gordon Allport examined how in-group love and out-group prejudice relate, and Marilynn Brewer argued that bias often arises from attachment to the in-group rather than hatred of others. Herbert Blumer linked prejudice to a sense of group position, and Lauren Rivera showed how similarity shapes hiring. Sociologists note that bias is influenced by power, since dominant groups can turn favoritism into discrimination. Critics point out that effects vary across cultures and contexts and that laboratory results may not generalize. Gordon Allport's contact hypothesis suggests that equal-status cooperation reduces bias. Today the concept informs research on prejudice, hiring, politics, organizations, and intergroup relations.