Mere group membership drives discrimination independent of economic self-interest.

Evidence

We have argued that social and realistic competition are conceptually distinct, although most often they are empirically associated in “real life.” In an experiment by Turner, Brown, and Tajfel (1979) an attempt was made to isolate the effects on intergroup behavior of the postulated autonomous processes attributed to a search for positive social identity. Children were used as subjects, and the manipulations involved decisions by the subjects about the distribution of payments for participation in the experiment, to be shared equally by the in-group, between the in-group and the outgroups that were made relevant or irrelevant to comparisons with the in-group’s performance. Monetary self-interest (of a magnitude previously ascertained to be of genuine significance to the subjects) would have produced no difference in the distribution decisions involving the two kinds of out-group; it would also have led to decisions tending toward maximum in-group profit (MIP) rather than toward maximum difference (MD). — John T. Jost and Jim Sidanius, Political Psychology, 2730

Categorization

• XREF: This is the classic minimal group paradigm (Tajfel) — connects to the broader social identity theory literature, and resonates with the user’s interest in how small cues of group belonging trigger bias.