That certain something! Focusing on similarities reduces judgmental uncertainty.

Comparative thinking is an efficient cognitive strategy that reduces judgmental uncertainty. However, comparisons may be conducted with a focus on similarities or differences. Similarity-focused comparisons seem to facilitate information-transfer, which has been suggested to drive the uncertainty-reducing effect of comparisons. This implies that similarity-focused comparisons reduce uncertainty more than dissimilarity-focused comparisons. Two experiments examine this assumption. In Study 1, a similarity-focus (compared to a difference-focus and a neutral control condition) increased judgmental certainty when the comparison was based on confident standard-knowledge. However, when the comparison was based on vague standard-knowledge the uncertainty-reducing effect diminished. Study 2 shows that a similarity-focus increases information-transfer and that a similarity-focus particularly enhanced certainty for judgments for which a standard-to-target information-transfer had occurred. These studies suggest that similarity-focused comparisons reduce judgmental uncertainty through the mechanism of information-transfer.