Do People With Lower Psychological Health Status Have a More Variable Self‐Concept? Analyzing Experience Sampling Data With a Mixed‐Effects Location‐Scale Model

While unstable and confused self‐concepts have been linked to poorer psychological health, less attention has been paid to the reverse direction—namely, whether poorer psychological health contributes to self‐concept instability. To address this question, three experience sampling studies were conducted in which university students rated their self‐concept approximately every 2–3 days. Variability in self‐concept was analyzed using a mixed‐effects location‐scale model, with both the mean and within‐person variance as outcomes. In Study 1, self‐concept was assessed using trait‐descriptive adjectives, and principal component analysis yielded two evaluative components. Lower psychological health, measured by the General Health Questionnaire (GHQ), was associated with greater variability in both components, even after controlling for self‐esteem, social acceptance/rejection, and relational context. Study 2, using the Ten‐Item Personality Inventory, replicated this effect for the evaluative component of the Big Five, but not for the descriptive one. Study 3, using a similar method, replicated the findings from Study 2 and additionally showed a GHQ effect on variability in the descriptive component. These results suggest that poor psychological health may contribute to self‐concept instability and highlight challenges in distinguishing genuine self‐concept variability from measurement error.