Evaluating the psychometric effects and assessment of inconsistent responding on the psychopathic personality inventory–revised in a correctional sample

The current study aimed to examine the effects of inconsistent responding on Psychopathic Personality Inventory–Revised (PPI-R; Lilienfeld & Widows, 2005) scale scores and the utility of the IR scale in detecting such responding in a correctional setting. The study employed an internally controlled method of simulating inconsistent responding by inserting ascending levels of computer-generated random responses into PPI-R protocols. Participants were 218 male inmates from a medium-security prison in central Kentucky in the United States. Results indicated that psychometric properties of PPI-R scores were substantially attenuated at as low as 40% of random responding. Additionally, results indicated that an Inconsistent Responding (IR) Scale cut-off of 40 would provide the best balance between sensitivity and specificity in detecting invalid PPI-R protocols. Overall, this study highlighted the utility of the IR Scale in self-report psychopathy measures and the need to consider such response biases in research and clinical settings.