When comparisons arise.

People acquire information about their abilities by comparison, and research suggests that people restrict such comparisons to those whom they consider sources of diagnostic information. We suggest that diagnosticity is often considered only after comparisons are made and that people do not fail to make nondiagnostic comparisons so much as they mentally undo them. In 2 studies, participants made nondiagnostic comparisons even when they knew they should not, and quickly unmade them when they were able. These results suggest that social comparisons may be relatively spontaneous, effortless, and unintentional reactions to the performances of others and that they may occur even when people consider such reactions logically inappropriate.