Multimethod Assessment of Psychopathy in Relation to Factors of Internalizing and Externalizing From the Personality Assessment Inventory: The Impact of Method Variance and Suppressor Effects

Research to date has revealed divergent relations across factors of psychopathy measures with criteria of internalizing (INT, anxiety, depression) and externalizing (EXT, antisocial behavior, substance use). However, failure to account for method variance and suppressor effects has obscured the consistency of these findings across distinct measures of psychopathy. Using a large correctional sample, the current study employed a multimethod approach to psychopathy assessment (self-report, interview and file review) to explore convergent and discriminant relations between factors of psychopathy measures and latent criteria of INT and EXT derived from the Personality Assessment Inventory (Morey, 2007). Consistent with prediction, scores on the affective—interpersonal factor of psychopathy were negatively associated with INT and negligibly related to EXT, whereas scores on the social deviance factor exhibited positive associations (moderate and large, respectively) with both INT and EXT. Notably, associations were highly comparable across the psychopathy measures when accounting for method variance (in the case of EXT) and when assessing for suppressor effects (in the case of INT). Findings are discussed in terms of implications for clinical assessment and evaluation of the validity of interpretations drawn from scores on psychopathy measures.