What you don’t know: The role played by errors of omission in imperfect self-assessments

Perceptions of ability often bear little relationship to objective performance. We suggest that people fail to judge their ability more accurately because they have little or no insight into their errors of omission (i.e., solutions they could have generated to problems but missed), although they can be perfectly aware of solutions found. Across five studies with tasks involving, for example, word games and research methodology, we found that participants gave weight to the number of solutions found when making self-evaluations, but not to solutions missed. When given explicit information about these errors of omission, participants gave them just as much weight as they did solutions found, and thus provided more accurate self-evaluations.