The contribution of judgment scale to the unskilled-and-unaware phenomenon: how evaluating others can exaggerate over- (and under-) confidence.

The unskilled-and-unaware phenomenon occurs when low performers tend to overestimate their performance on a task, whereas high performers judge their performance more accurately (and sometimes underestimate it). In previous research, this phenomenon has been observed for a variety of cognitive tasks and judgment scales. However, the role of judgment scale in producing the unskilled-and-unaware phenomenon has not been systematically investigated. Thus, we present four studies in which all participants judged their performance on both a relative scale (percentile rank) and an absolute scale (number correct). The studies included a variety of performance tasks (general knowledge questions, math problems, introductory psychology questions, and logic questions) and test formats (multiple-choice, recall). Across all tasks and formats, the percentile-rank judgments were less accurate than the absolute judgments, particularly for low and high performers. Furthermore, in Studies 1-3, the absolute judgments were highly accurate, even when the percentile-rank judgments were not. Thus, differences in the accuracy of percentile-rank judgments across skill levels do not always represent differences in self-awareness, but rather they may arise from difficulties that performers have at evaluating how well others are performing. Most importantly, the unskilled-and-unaware phenomenon on a relative scale does not guarantee inaccurate self-evaluations of absolute performance.