Assessing Personality States – The Development and Validation of a Five-Factor Model Personality States Inventory

With growing interest in within-person variations in personality, reliable instruments for assessing personality states are essential. A literature review revealed most studies use ad-hoc measures with little focus on content validity. This research presents the development and validation of the German Five-Factor Model Personality States Inventory (FFM-PSI) for intensive longitudinal studies, emphasizing facet-level coverage of the five-factor model.In two studies, participants completed the FFM-PSI along with mood and situation characteristics several times during three days and provided ratings of personality traits. Study 1 (N = 170 individuals / 1,549 assessments, 77% women, median age = 25) focused on item selection and establishing initial psychometric properties, while Study 2 (N = 1,725 persons / 18,905 assessments, 70% women, median age = 25) cross-validated the findings from Study 1. Results provide evidence for structural validity, internal consistency, and convergent validity with established personality trait measures, as well as expected associations with mood and situation characteristics. The FFM-PSI also effectively captured meaningful within-person variability.This research supports the FFM-PSI's psychometric properties, highlighting the importance of valid and reliable measures for studying dynamic personality expressions and calls for further conceptual and empirical work in this field.