Using the Psychopathic Personality Inventory to identify subtypes of antisocial personality disorder

Purpose: Poythress, Edens, et al. (2010) recently used cluster analysis to identify subtypes of antisocial and psychopathic offenders using a diverse collection of theoretically important clustering variables. Two predicted subtypes, primary and secondary psychopathy, were identified, in addition to non-psychopathic and (unexpectedly) fearful psychopathic offenders. The purpose of the present research was to determine whether these clusters could be replicated using a single self-report measure, the Psychopathic Personality Inventory (PPI; Lilienfeld & Andrews, 1996). Method: Study 1: We used discriminant function analysis (DFA) to predict cluster membership for the Poythress et al. subtypes based solely on the eight subscales of the PPI. Results: Study 1: Though overall classification accuracy with the original clusters was poor, PPI-derived subtypes differed from each other in theoretically consistent ways on several criterion measures. Method: Study 2: We used the PPI-based DFA to classify a separate sample of prison inmates from a prior PPI study (Edens et al., 2008). Results: Study 2: As predicted, inmates classified into the secondary psychopathy subgroup demonstrated the highest rates of aggressive misconduct whereas non-psychopathic were the least prone to engage in misconduct. Conclusion: The PPI may serve as a relatively simple method of identifying theoretically meaningful subtypes of psychopathic offenders. (C) 2012 Elsevier Ltd. All rights reserved.