We conducted two studies in which participants reported their beliefs and preferences and estimated the beliefs and preferences of political in-group members who were either fellow participants in the study (Study 1) or members of the general American population (Study 2). This procedure allowed us to examine whether similar patterns of effects would emerge even when participants thought about political in-group members in different contexts. In Study 2, we replicated and extended Study 1 by examining whether the desire to feel unique explains in part ideological differences in estimating similarity to political in-group members. Finally, previous research has shown that individuals perceive more similarity between their own beliefs and those of other individuals (i.e., perceive greater consensus) when the beliefs are socially desirable or personally important. To rule out the possibility that these factors explain ideological differences in perceiving similarity to political in-group members, we measured the perceived social desirability of the items to which participants responded in both studies. In addition, in Study 2, we measured the personal importance of the items to rule out the possibility that this factor would explain ideological differences in perceiving similarity.Here is their brief abstract.
In two studies, we demonstrated that liberals underestimate their similarity to other liberals (i.e., display truly false uniqueness), whereas moderates and conservatives overestimate their similarity to other moderates and conservatives (i.e., display truly false consensus; Studies 1 and 2). We further demonstrated that a fundamental difference between liberals and conservatives in the motivation to feel unique explains this ideological distinction in the accuracy of estimating similarity (Study 2). Implications of the accuracy of consensus estimates for mobilizing liberal and conservative political movements are discussed.