Social Categorisation and Intergroup Behaviour.

Five experiments were carried out to explore the ways in which individuals structure the social environment under minimal conditions, re-interpret minimal intergroup differences, and re-define their group memberships through ’’psychological" social mobility, in a way which achieves a more favourable social identity for them. In the first two experiments, the interpersonal relationships between subjects were defined by at least 8 levels of similarity on one or more dimensions of differing salience. Social categorisation was introduced by the subjects. They treated the most similar others positively, the most dissimilar others negatively and the ’neutral' others without bias. A consistent adoption by the subjects of certain similarity levels as boundaries demarcating categories was observed. This finding is discussed in relation to the social rules and meanings which the subjects perceived to be relevant to the situation. In the third experiment, a real and important, and an artificial and seemingly trivial criterion for social categorisation were introduced in independent and identical settings. It was hypothesised in both instances that differences between groups would be treated as similarly important, since they were the only basis for intergroup differentiation and ingroup favouritism. This hypothesis was confirmed. Two further studies, designed to demonstrate "psychological" social mobility, are reported. The first involved real groups - ’high’ valued and ’low' valued Nationalities respectively. The second study, which was a replication and extension of Allen and Wilder's (1975) experiment, involved artificially created groups. There were 8 conditions across which the level of similarity of the subjects with the ingroup and outgroup was varied on both trivial and important criteria. In both experiments, increased identification with highly valued outgroups was observed. Certain elaborations of Tajfel’s theory of intergroup behaviour are proposed, with the aim of placing more emphasis on the social evaluative system influencing behaviour and the process of "psychological" social mobility