Intergroup discrimination can be defined broadly as differential treatment of individuals based on social category membership. In many contexts, discrimination takes the form of ingroup bias, whereby members of one's own social categories are evaluated more positively or responded to more favorably than members of other social categories (outgroups). In much of the social psychological literature, discrimination is viewed as the behavioral component of prejudice.
In light of this conflation of prejudice and discrimination, it is interesting that ingroup bias is often referred to as ingroup favoritism (Tajfel, Billig, Bundy, & Flament, 1971), whereas prejudice is most often defined as outgroup hostility (see Dixon, Levine, Reicher, & Durrheim, 2012; Greenwald & Pettigrew, 2014). This chapter reviews theory and empirical research on the relationship between ingroup bias and outgroup hostility and argues that it is important to distinguish between these two loci of discrimination and to recognize that much intergroup discrimination takes the form of ingroup favoritism in the absence of outgroup antagonism.
Ingroup Bias and Ethnocentrism
Ethnocentrism was described by Sumner as a universal characteristic of human social groups whereby
a differentiation arises between ourselves, the we-group, or in-group, and everybody else, or the others-group, out-groups. The insiders in a we-group are in a relation of peace, order, law, government, and industry, to each other … Ethnocentrism is the technical name for this view of things in which one's own group is the center of everything, and all others are scaled and rated with reference to it … Each group nourishes its own pride and vanity, boasts itself superior, exalts its own divinities, and looks with contempt on outsiders.(Sumner, 1906, pp. 12–13)
Over the past 50 years of empirical research on intergroup relations, this propensity to privilege ingroupers over outgroupers has been well established, confirming the power of we-they distinctions to produce differential evaluation, liking, and treatment of other persons depending on whether or not they are identified as members of the ingroup category.