The Hare Psychopathy Checklist (PCL; Hare, Neumann, & Mokros 2018) scales are among the most widely used forensic assessment tools. Their perceived utility rests partly on their ability to assess stable personality traits indicative of a lack of conscience, which then facilitates behavioral predictions useful in forensic decisions. In this systematic review, we evaluate the empirical evidence behind 3 fundamental justifications for using the PCL scales in forensics, namely, that they are empirically predictive of (1) criminal behavior, (2) treatment outcomes, (...) and (3) a lack of conscience. We found the PCL scales can predict criminal behavior to a statistically significant degree, though with important limitations. We found no evidence of PCL psychopathy being predictive of treatment and rehabilitation outcomes. We found no evidence of PCL psychopathy being predictive of a lack of conscience. These findings disprove widespread beliefs about PCL psychopathy among forensic practitioners and questions the current and future role of the PCL scales in forensic settings. (shrink)

Questionable research practices are a well-recognized problem in psychology. Coding bias, or the tendency of review studies to disproportionately cite positive findings from original research, has received comparatively little attention. Coding bias is more likely to occur when original research, such as neuroimaging, includes large numbers of effects, and is most concerning in applied contexts. We evaluated coding bias in reviews of structural magnetic resonance imaging studies of PCL-R psychopathy. We used PRISMA guidelines to locate all relevant original sMRI studies (...) and reviews. The proportion of null-findings cited in reviews was significantly lower than those reported in original research, indicating coding bias. Coding bias was not affected by publication date or review design. Reviews recommending forensic applications—such as treatment amenability or reduced criminal responsibility—were no more accurate than purely theoretical reviews. Coding bias may have contributed to a perception that structural brain abnormalities in psychopaths are more consistent than they actually are, and by extension that sMRI findings are suitable for forensic application. We discuss possible sources for the pervasive coding bias we observed, and we provide recommendations to counteract this bias in review studies. Until coding bias is addressed, we argue that this literature should not inform conclusions about psychopaths' neurobiology, especially in forensic contexts. (shrink)