Understanding psychopathy through an evaluation of interpersonal behavior: testing the factor structure of the interpersonal measure of psychopathy in a large sample of jail detainees.

Interpersonal characteristics are core features of the psychopathy construct which have a unique pattern of correlations with a variety of external correlates. To improve the assessment of interpersonal traits, the current study evaluated the internal structure of the Interpersonal Measure of Psychopathy (IM-P) through exploratory and confirmatory factor analyses (CFA) in a large sample of jail inmates. A 17-item, 3-factor (Dominance, Grandiosity, and Boundary Violations) structure evidenced good fit in European American inmates. A second CFA demonstrated good fit for this structure in a sample of African American inmates. Moreover, a multigroup CFA indicated structural invariance between European and African American inmates. External validity was tested and demonstrated through positive correlations between IM-P factor scores and Psychopathy Checklist--Revised total and facet scores (R. D. Hare, 2003) and antisocial personality disorder symptoms and diagnoses. Modest correlations between Grandiosity scores and scores on the Shipley Institute of Living Scale--Revised (R. A. Zachary, 1994) were also observed. Finally, a step-down hierarchical regression was conducted to test for racial bias of the IM-P factor scores in relation to external correlates. Little evidence was found for slope bias, but there was evidence of intercept bias for some analyses. Implications and advantages of assessing psychopathy through a comprehensive evaluation of interpersonal traits are discussed.