By Emma Young

What lies at the dark heart of psychopathy? Is it a lack or emotion and empathy, a willingness to manipulate others – or, perhaps, a failure to take responsibility for misdeeds? All of these traits, and many more, are viewed as aspects of a psychopathic personality. But there’s still a debate among experts about which of these are core, and which less important.

Now a new study of 7,450 criminal offenders in the US and the Netherlands, published in the Journal of Abnormal Psychology, has identified what the researchers believe are the psychopath’s most “central” traits . But while there were striking similarities in the data from the two countries, there were also intriguing differences. This raises the question: does the meaning of the term “psychopath” vary between cultures?

Researchers from the Netherlands and the US, led by Bruno Verschuere at the University of Amsterdam, analysed the offenders’ scores on the widely-used Psychopathy Checklist – Revised (PC-R). The PC-R comprises 20 questions about a range of traits related to four aspects of psychopathy: affective problems (a lack of empathy, fearlessness, and shallow emotional experience); interpersonal (being detached or a pathological liar, for example); lifestyle (being irresponsible and having poor behavioural control, for example); and being antisocial (showing early behavioural problems, and later criminal behaviour).

Between 20 to 22 per cent of the US offenders, and 28 per cent of the offenders in the Netherlands, were clinical psychopaths, based on their PC-R scores (as judged by trained research assistants in each country who drew on “extensive interview and collateral file information” for each offender). This difference between the countries was not a surprise, as the group from the Netherlands were all violent, mentally unwell offenders, whereas one US group consisted of general offenders from state prisons in Wisconsin, and the other comprised offenders in jail or on substance treatment programmes in five other US states.

The researchers performed a “network analysis” on the offenders’ PC-R scores, mainly focused on centrality – so, among clinical psychopaths, identifying which item or items were most often present. But they also looked at relationships between items – so if pathological lying was present, for example, then identifying which other items were often, or rarely, present.

The results showed that “callousness/lack of empathy” was the most central item in both of the US samples. As the researchers note, “this aligns with classic clinical descriptions and prototypicality studies of psychopathy.” But for the offenders from the Netherlands, while “callousness/lack of empathy” was fairly central, a “parasitic lifestyle” and “irresponsibility” were most central.

For the US samples, the items that appeared most peripheral to psychopathy were “many short-term marital relations”, “lack of realistic long-term goals” (in the Wisconsin offenders only) and “revocation of conditional release” (this refers to failing to fulfil the terms of probation, for example).

For the offenders from the Netherlands, “Promiscuous sexual behaviour” and “many short-term marital relations” were also among the most peripheral items, but, surprisingly, so too was “shallow affect”, an item that was actually the second most-central for the Wisconsin group.

In a bid to address the non-geographical differences between the US and Dutch groups, the researchers extracted a subsample from the Dutch group, excluding those with indications of current or past severe psychopathology, but the results still showed that a parasitic lifestyle and irresponsibility (not callousness, as in the US groups), were the most central items for psychopaths in the Netherlands.

The results raise the possibility, the researchers suggest, that there might be cross-cultural differences in how psychopathy manifests – or at least in how the PC-R is scored by trained raters in different counties. Further work should help to clarify this.

“Extending network analyses to different measures, samples and cultures should shed further light on the core characteristics of psychopathy,” they write, “and perhaps ultimately on the unresolved question of what psychopathy is.”

—What features of psychopathy might be central? A network analysis of the Psychopathy Checklist-Revised (PCL-R) in three large samples

Emma Young (@EmmaELYoung) is Staff Writer at BPS Research Digest