The Effect of Certainty on Consensus Judgments

Abstract

To investigate the effect of opinion certainty on attributions of opinion similarity, we examined projections of own verdict on a court case. The first study was correlational in nature; it assessed the relation between self-ratings of certainty of verdict correctness and attributions of own verdict to others. In two additional studies, we used conceptually distinct operations to manipulate certainty experimentally and again measured attributions of verdict similarity. Taken together, the three studies provide converging evidence that people are more apt to attribute their opinion to others when they are highly certain as opposed to uncertain about its correctness. Further, those who rendered a verdict of guilty (as opposed to not guilty) attributed their vote to a larger portion of people. Independent of own verdict and manipulated certainty, subjects ascribed their opinion to liked targets more than to disliked targets. The findings are discussed in relation to two competing theoretical positions regarding the effect of opinion certainty on opinion projection: Cognitive availability and social comparison.