September 4, 2014

More studies finding bias in PCL-R measurement of psychopathy

I've been reporting for quite some time about problems with the reliability and validity of the Psychopathy Checklist (PCL-R), a popular instrument for measuring psychopathy in forensic settings. It is a critical issue in forensic psychology, because of the massively prejudicial nature of the term "psychopath." Once a judge or jury hears that term, pretty much everything else sounds like "blah blah blah."

Now, the journal Law and Human Behavior has published two new studies -- one from the U.S. and the other from Sweden -- adding to the ever-more-persuasive line of research on PCL-R rater bias. It's high time for a critical examination of whether the PCL-R belongs in court, but I doubt that will happen anytime soon because of its efficacy for obtaining desired results. At the bottom of each abstract, I've provided contact information so that you can request the full articles from the authors.

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Field Reliability of the Psychopathy Checklist-Revised Among Life Sentenced Prisoners in Sweden

Joakim Sturup, John F. Edens, Karolina Sörman, Daniel Karlberg, Björn Fredriksson and Marianne Kristiansson Law and Human Behavior 2014, Vol. 38, No. 4, 315-324

ABSTRACT: Although typically described as reliable and valid, the Psychopathy Checklist-Revised (PCL-R) has come under some criticism by researchers in the last half-decade due to evidence of poor interrater reliability and adversarial allegiance being reported in applied settings in North America. This study examines the field reliability of the PCL-R using a naturalistic test–retest design among a sample of Swedish life sentenced prisoners (N 27) who had repeatedly been assessed as part of their application to receive a reduced prison term. The prisoners, who were assessed by a team of forensic evaluators retained by an independent government authority, had spent on average 14 years in prison with a mean time from Assessment 1 to Assessment 2 of 2.33 years. The overall reliability of the PCL-R (ICCA1) was .70 for the total score and .62 and .76 for Factor 1 and 2 scores, respectively. Facet 1–3 scores ranged from .54 to .60, whereas Facet 4 was much higher (.90). Reliability of individual items was quite variable, ranging from .23 to .80. In terms of potential causes of unreliability, both high and low PCL-R scores at the initial assessment tended to regress toward the mean at the time of the second evaluation. Our results are in line with previous research demonstrating concerns regarding the reliability of the PCL-R within judicial settings, even among independent evaluation teams not retained by a particular side in a case. Collectively, these findings question whether the interpersonal (Facet 1) and affective (Facet 2) features tapped by the PCL-R are reliable enough to justify their use in legal proceedings.

Request a copy from the author. 
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Evaluator Differences in Psychopathy Checklist-Revised Factor and Facet Scores 

Marcus T. Boccaccini, Daniel C. Murrie, Katrina A. Rufino and Brett O. Gardner Law and Human Behavior 2014, Vol. 38, No. 4, 337-345

ABSTRACT: Recent research suggests that the reliability of some measures used in forensic assessments—such as Hare’s (2003) Psychopathy Checklist-Revised (PCL-R)—tends to be weaker when applied in the field, as compared with formal research studies. Specifically, some of the score variability in the field is attributable to evaluators themselves, rather than the offenders they evaluate. We studied evaluator differences in PCL-R scoring among 558 offenders (14 evaluators) and found evidence of large evaluator differences in scoring for each PCL-R factor and facet, even after controlling for offenders’ self-reported antisocial traits. There was less evidence of evaluator differences when we limited analyses to the 11 evaluators who reported having completed a PCL-R training workshop. Findings provide indirect but positive support for the benefits of PCL-R training, but also suggest that evaluator differences may be evident to some extent in many field settings, even among trained evaluators.

Request from author.

More of my coverage of the PCL-R is available HERE. An NPR series on the controversy -- including an essay by me -- is HERE.

Hat tip: Brian Abbott

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