IntroductionConfidence is defined as the feelings and thoughts people have during a task that result in judgments about their performance. Evidence suggests that confidence is trait-like, but thus far research on the relative match between confidence and accuracy has been primarily restricted to over-confidence effects, and subject to the methodological flaws involved with using difference scores. We sought to answer an exploratory question in this research, whether discrepancies in ability and confidence in either direction reliably predicted individual differences on a broad-spectrum and commercially available personality test, the California Psychological Inventory (CPI260).MethodsParticipants were 220 employed adults who had previously taken the CPI260 for career development purposes. They were invited to complete a measure of cognitive ability and confidence in return for feedback on the same. Data were modeled using polynomial regression and response surface analysis, to determine whether and how CPI260 personality traits were associated with matches or mismatches between accuracy and confidence in the same test.ResultsWe identified negative curvilinear effects along the line of disagreement for four CPI260 scales, suggesting that both under- and over-confidence were associated with personality.DiscussionIn contrast to our expectations, individuals who were under-confident and those who were over-confident had lower achievement potential, less social confidence, and more inner conflict than other individuals in this sample. Although preliminary, these findings suggest that both over-confident and under-confident individuals are aware of potential weaknesses that impede their functioning.