Three studies were conducted to test the hypothesis that subjects would overestimate the proportion of their peers who shared their opinion on an issue and that they would perceive their own opinion group as consisting of people with a wider and more diverse range of values and outlooks than those holding different opinions. The first study was conducted following a period of intense debate about sexism on a college campus. Subjects estimated student opinion on issues related to sexism and indicated how diverse or similar they perceived supporters and nonsupporters of the women's movement to be. In a second study subjects estimated the proportion of students who evaluated President Carter's performance as good, fair, or poor and then indicated how diverse or similar the three groups of students were who held these various opinions. A third study closely replicated the second, using the issue of divestiture of college-owned stock in South Africa. In all three studies, subjects were divided into groups on the basis of their own attitudes. Results consistently supported the hypotheses.

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Copyright © 1979 Society of Experimental Social Psychology. This article first appeared in Journal of Experimental Social Psychology 15, no. 6 (November 1979): 570-81. doi:10.1016/0022-1031(79)90052-0

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