Is a Trait Really the Mean of States?: Similarities and Differences Between Traditional and Aggregate Assessments of Personality

Although several definitions exist, a personality trait can be defined as the average or expected value of personality-relevant behaviors. However, recent evidence suggests that, while trait questionnaires and aggregated momentary assessments of personality are highly related, they may also differ in meaningful ways. In this study, we examine the relationship between trait and mean state personality. Results indicate that these two assessment strategies, although highly related, do not show convergence (r = .39-.64) levels that would signify an equity of constructs. In line with this, these two assessment strategies show differential predictive utility. Although the pattern of this differential predictive utility suggests that measurement error may account for differences, the difference between trait and mean state personality predicts affect in a manner consistent with self-discrepancy theory. Thus, although these two constructs are highly related, the differences between trait and mean state personality are meaningful.