What's this psychopathy hoo-ha all about?

A psychology paper, by David Cooke and Jennifer Skeem, that's critical of the dominant tool for measuring psychopathy, has finally been published after years lying dormant. The delay, according to reports, was due to threats of libel by lawyers representing Robert Hare, author of the criticised tool.

Curiously, back in 2007, when the contentious paper was first moth-balled, a similar and related paper (free to access), also by Cooke and Skeem, plus statistician Christine Michie, was published in the British Journal of Psychiatry. In fact, this paper describes itself as the 'analytical' companion to the 'logical and theoretical' paper that was buried for so long.

So what did the paper that managed to get published back in 2007 have to say? Echoing the scholarly tussles that have surrounded the measurement of many factors in psychology, such as intelligence and personality, Cooke and his co-authors grapple with how best to provide a concrete measurement of a slippery abstract concept, in this case psychopathy.

The gist of their argument is that psychopathy is most appropriately measured by a three-factor version of Hare's Psychopathy Checklist-Revised (PCL-R), tapping: arrogant and deceitful interpersonal style; deficient affective experience; and impulsive and irresponsible behavioural style. In short-hand you could say this translates as nasty, unemotional and uninhibited. The point of contention is that Hare's widely used PCL-R measure of psychopathy adds a fourth factor - criminality.

Cooke and his colleagues think this is a big mistake and to support their claims they ran a number of different versions of the psychopathy checklist on answers given by over 1000 adult male offenders. In conclusion, they wrote:

'Psychopathy and criminal behaviour are distinct constructs. If we are to understand their relationships and, critically, whether they have a functional relationship, it is essential that these constructs are measured separately. This is particularly critical within the context of the Dangerous and Severe Personality Disorders project, where individuals are detained because of the assumption of a functional link between their personality disorder and the risk that they pose.'

In other words, a measure that conflates psychopathy and criminality risks confusing any attempts to understand the links between psychopathy and criminal acts such as rape and murder. Moreover, if raping and murdering become part of the definition of psychopathy, then what sense is there of running a risk assessment on a person diagnosed as psychopathic?

Cooke et al are currently developing what they describe as a 'more comprehensive' model of the construct of psychopathy based on 33 symptoms grouped into six domains. Criminality isn't one of them.
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Cooke, D., Michie, C., & Skeem, J. (2007). Understanding the structure of the Psychopathy Checklist - Revised: An exploration of methodological confusion. The British Journal of Psychiatry, 190 (49) DOI: 10.1192/bjp.190.5.s39

Link to Mind Hacks update on the saga of the buried paper (thanks to Mind Hacks for alerting me to this unfolding story).
Link to In the News Forensic Psychology blog, with more updates.
Link to related (paywalled) Science journal news item.