A Multi-Method Study of Interpersonal Complementarity and Mentalization.

Research finds cross-sectional relationships between mentalizing impairments and maladaptive personality traits. The current study connects mentalizing impairments to dynamic interpersonal processes using a multi-method design. A sample of 218 participants completed the Movie for the Assessment of Social Cognition (MASC; Dziobek et al., 2006) to assess mentalizing ability. Subsequently, participants rated their agentic and communal behavior and their perception of interaction partners' agentic and communal behavior over 21-days. Mentalizing ability moderated the within-person relationship between behavior and perception for both agency and communion. Worse performance on the MASC was associated with weaker interpersonal complementarity, suggesting that mentalizing impairments lead to deviations from expected patterns of behavior and perception across interpersonal situations. These findings confirm the assumption of Contemporary Integrative Interpersonal Theory that mentalization impairments can disrupt normative interpersonal processes (Cain et al., 2024; Pincus & Hopwood, 2012).