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

PurposePoythress, 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 1We 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 1Though 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 2We used the PPI-based DFA to classify a separate sample of prison inmates from a prior PPI study (Edens et al., 2008).Results: Study 2As 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.ConclusionThe PPI may serve as a relatively simple method of identifying theoretically meaningful subtypes of psychopathic offenders.

► Study 1 assessed the replicability of previously derived ASPD subtypes
► ASPD subtypes differed on theoretical variables and behavioral outcomes
► Study 2 evaluated utility of classification system in independent dataset
► Groups differed in useful ways including recidivism type and institutional misconduct
► Evidence for personality and behavioral differences in ASPD offenders