Social categorization, interpersonal attraction and group formation

Abstract

It is widely assumed that interpersonal attraction is the primary psychological basis of group formation. Recent research disputes this view: the external designation of individuals as members of different groups (social categorization) in the absence of interpersonal relationships and interdependence seems sufficient for private acceptance of group membership and discriminatory intergroup behaviour. The present experiment manipulated interpersonal attraction and social categorization orthogonally: 80 school pupils were randomly assigned one of two types of personal code number (in the 40s or the 50s) on an explicitly criterial (the 40s were liked, the 50s disliked) or random basis, and categorized into groups or not in terms of these numbers. Interpersonal attraction was necessary and sufficient for group formation in the non‐categorization conditions but not necessary in the categorization conditions. Social categorization on a positive, negative, or arbitrary basis produced favouritism to similar others. Moreover, negatively categorized subjects were as discriminatory as positively categorized and more discriminatory than randomly categorized ones. The data are interpreted as evidence for the importance of self‐defining social categorizations in group formation. An explanation of the role of interpersonal attraction is offered in line with this interpretation.