Clarifying Conceptions Underlying Adult Psychopathy Measures: A Construct Validity Metric Approach
Although the Psychopathy Checklist-Revised (PCL-R) and Psychopathic Personality Inventory (PPI) ostensibly measure the same construct, they seem to emphasize different conceptions of psychopathy. This study was designed to clarify these differences by testing how well the PCL-R and PPI map alternative conceptions of psychopathy. Construct validity metrics were used to compare patterns of associations between psychopathy measures and 14 theory-relevant criterion variables that were observed in a sample of 1,281 offenders—with patterns of associations that were predicted based on alternative psychopathy conceptions. PCL-R total scores were most consistent with Karpman’s affective dysfunction-centered secondary conception, and PPI total scores were most consistent with the McCords’ lovelessness-based conception. Although similarities emerged at the factor level, the PPI demonstrated higher levels of consistency between theory-based predictions and observed relations than did the PCL-R. These results provide direction for refining measures in future research and interpreting PCL-R and PPI scores in current practice.
Keywords: psychopathy, Psychopathy Checklist-Revised, Psychopathic Personality Inventory, construct validity