The ''false consensus effect'' refers to the tendency to overestimate consensus for one's attitudes and behaviors. This overestimation may occur because people are biased in viewing their own positions as normative, or simply because they overgeneralize from case information, with their own positions representing one salient item of case information. Four studies were conducted to demonstrate that people overestimate consensus for their own performance outcomes and to show that this overestimation occurs independently of the influence of case information about the performance of others. Subjects in each study received either personal information about their success or failure on a bogus test of social sensitivity or case informance feedback. The results of each study showed that subjects overestimated, on the basis of their own performance outcome, the number of their peers who would succeed or fail at the task, but did not overestimate on the basis of case information alone. These findings support the assumption that has guided research on the false consensus effect, namely, that people are biased in perceiving their own attitudes, behaviors, and outcomes as normative. These findings also show that the false consensus effect is not simply a product of the overgeneralization from case information. (C) 1995 Academic Press, Inc.