A new article from Zina Lee, Jessica R. Klaver and Stephen D. Hart reminds us that we need to be careful when assuming that promising results from lie detection studies where people without serious psychopathology are the subjects can be generalised to a forensic context.
Lee et al wondered whether a tool commonly used for assessing credibility of verbal or written statements could be used to discriminate lying from truth-telling psychopaths. It’s been estimated that up to about 2% of the general population and between 15 and 25% of incarcerated criminals meet the criteria for psychopathy. One of the characteristics of psychopaths is their ability and willingness to deceive others – they are pathological liars who think nothing of manipulating and deceiving others for their own gain. This pathological lying, coupled with superficial charm and inability to feel guilt or remorse, makes a psychopath a particularly dangerous and unpleasant individual.
Previous studies of psychopaths’ deceptive behaviour have reported mixed results, with some suggesting that psychopaths are effective at deceiving others, whilst others report no differences between psychopathic and non-psychopathic individuals. When it comes to verbal behaviour, there is some evidence that psychopaths’ deceptive verbal behaviour may differ from that of non-psychopaths’, being less coherent and less cohesive. Lee et al’s study is, however, the first to investigate psychopathy and verbal indicators of deception in a systematic fashion, using Criteria Based Content Analysis (CBCA).
The researchers asked 45 randomly selected prisoners to tell the truth about the crime for which they had been convicted and to lie about a theft they did not commit. In summary, the authors “found fewer, and different, distinguishing features between true and false accounts among psychopathic and non-psychopathic offenders” (p.81). The results included:
- More appropriate details provided by psychopathic offenders compared to nonpsychopathic offenders when lying (but no difference when telling the truth)
- No difference in narrative length between the true and false conditions among psychopathic offenders, and for both groups, truthful narratives were longer than false narratives
- For psychopathic offenders, spontaneous corrections more frequent when lying compared to telling the truth. This is opposite to the finding with non-criminal populations – according to CBCA, the presence of spontaneous corrections is thought to be associated with credibility.
- Psychopathic offenders judged less credible than non-psychopathic offenders, even when telling the truth. Seven times less likely to be judged credible to be precise.
- Narratives produced by psychopathic offenders were judged to be less coherent overall than narratives produced by non-psychopathic offenders.
The study has limitations, the most important being the relatively small sample size, the lack of stakes (the participants had no particular motivation to lie) and the fact that participants were given very little time to prepare their lies. The authors also wonder whether the fact that participants gave uninterrupted narratives might have given an unrealistic impression of psychopaths’ lying ability:
It may be that during an interaction, psychopathic individuals are able to pick up on subtle cues or adjust their speech and presentation based on feedback from the listener. Future studies examining individual variables within the listener (e.g. naive or gullible) or situational factors associated with the interaction (e.g. greater distractions in the environment) may provide further insight into how psychopaths successfully manipulate and deceive others.
- Zina Lee, Jessica R. Klaver and Stephen D. Hart (2008). Psychopathy and verbal indicators of deception in offenders. Psychology, Crime & Law 14(1):73-84
- Robert Hare’s site on psychopathy
- Vrij, Aldert (2005). Criteria-Based Content Analysis: A Qualitative Review of the First 37 Studies. Psychology, Public Policy, and Law. 11(1) 3-41
- Hervey Cleckley’s classic text on psychopathology is available on line: The Mask of Sanity (pdf, 1.4MB)
Abstract below the fold.