"The present study is an examination of the attitude changes which occur over time when reference groups and membership groups are identical and when they are disparate . . ‥ The Ss were women students at a large private coeducational university . . ‥ In the social context of the lives of the subjects, and in a natural social experiment which provided randomization of the relevant condition effects, the influence of both membership and reference groups on attitude change was assessed. All subjects shared a common reference group at the start of the period of the study. When divergent membership groups with disparate attitude norms were socially imposed on the basis of a random event, attitude change in the subjects over time was a function of the normative attitudes of both imposed membership groups and the individuals' reference groups. The greatest attitude change occurred in subjects who came to take the imposed initially nonpreferred, membership group as their reference group." (PsycINFO Database Record (c) 2006 APA, all rights reserved)