ABSTRACT
When social participants are brought together in structures either formal or informal, or when they are endowed with certain common attributes, bound together by their links to a common source, or their involvement in a collective activity, or that they share a common fate, they form what cognitive psychology calls a social group. In a heterogeneous and stratified society, in order to understand the contact situations between different socio-ethnic groups one must analyse the objective constraints and the political system in place. When a society claims to incorporate all the differences among groups by having them all adopt the dominant values and norms, it practises a policy of assimilation. With the development of a field of study on social cognition, since the seventies, has come the attempt to identify factors involved in cognitive stereotyping.
