Category Archives: CBCA

Psychopathy and verbal indicators of deception in offenders

psychopath bookA 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.

Reference:

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Photo credit: kenchanayo, Creative Commons License

Abstract below the fold.

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Cues to Deception and Ability to Detect Lies as a Function of Police Interview Styles

interrogateIf you were a police officer, what sort of interview style would offer you the best chance of detecting whether or not your interviewee was telling lies? Aldert Vrij and his colleagues ran a study to find out:

In Experiment 1, we examined whether three interview styles used by the police, accusatory, information-gathering and behaviour analysis, reveal verbal cues to deceit, measured with the Criteria-Based Content Analysis (CBCA) and Reality Monitoring (RM) methods. A total of 120 mock suspects told the truth or lied about a staged event and were interviewed by a police officer employing one of these three interview styles. The results showed that accusatory interviews, which typically result in suspects making short denials, contained the fewest verbal cues to deceit. Moreover, RM distinguished between truth tellers and liars better than CBCA. Finally, manual RM coding resulted in more verbal cues to deception than automatic coding of the RM criteria utilising the Linguistic Inquiry and Word Count (LIWC) software programme.

In Experiment 2, we examined the effects of the three police interview styles on the ability to detect deception. Sixty-eight police officers watched some of the videotaped interviews of Experiment 1 and made veracity and confidence judgements. Accuracy scores did not differ between the three interview styles; however, watching accusatory interviews resulted in more false accusations (accusing truth tellers of lying) than watching information-gathering interviews. Furthermore, only in accusatory interviews, judgements of mendacity were associated with higher confidence. We discuss the possible danger of conducting accusatory interviews.

In the discussion, Vrij and colleagues summarise:

The present experiment revealed that style of interviewing did not affect on overall accuracy (ability to distinguish between truths or lies) or on lie detection accuracy (ability to correctly identify liars). In fact, the overall accuracy rates were low and did not differ from the level of chance. This study, like so many previous studies (Vrij, 2000), thus shows the difficulty police officers face when discerning truths from lies by observing the suspect’s verbal and nonverbal behaviours.

In other words, if law enforcement officers want to increase their chances of detecting deception, they need to make sure interviewers use an information gathering approach. But simply watching that interview (live or on tape) might not help them decide whether or not the suspect is telling the truth – they may need to subject a transcript to linguistic analysis to give themselves the best chance.

Even if it doesn’t result in better ‘live’ judgements of veracity, an information gathering approach has another advantage for the law enforcement officer: it maximises the number of checkable facts elicited from the suspect, and being able to check a fact against the truth is pretty much the most effective means of uncovering false information. Of course, someone can provide false information without deliberately lying: if they have misremembered something, for instance, or are passing on something that someone else lied to them about. But then the point of any law enforcement interview is to get to the truth, which is a higher goal than simply uncovering a liar, in my opinion.

As always with lab-based studies, there are some limitations. Vrij et al., for instance, acknowledge that “in practice elements of all three styles may well be incorporated in one interview” but explain that “we distinguished between the three styles in our experiments because we can only draw conclusions about the effects of such styles only by examining them in their purest form”.

Further problems, which are difficult to overcome in structured lab settings, are caused because participants were assigned randomly to ‘guilty’ (liars) or ‘innocent’ (truth tellers) conditions. In the real world, individuals who are prepared put themselves in a situation in which they might later have to lie may differ in their ability to lie effectively than those who try to stay out of such situations. And real guilty suspects make a decision about whether they are going to lie (a few confess from the start, others will offer partial or whole untruths). It’s an issue that is open to empirical test: let participants choose whether they want to be in the ‘guilty’ or ‘innocent’ conditions (or have four conditions: guilty choice/guilty no choice/innocent choice/innocent no choice).

Also, in this study the liars were told what lie to tell (as opposed to being able to make one up). Real guilty suspects who decide to lie will presumably choose a lie that they they think they stand a good chance of being able to get away with. In real world conditions, the perception by the guilty individual of what sort of situation they’re in, the evidence against them, the plausible story they can tell to explain away the evidence, and their ability to lie effectively are probably all important.

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Photo credit: scottog, Creative Commons License

Criteria-Based Content Analysis: An empirical test of its underlying processes

The latest issue of Psychology, Crime and Law features an article by Aldert Vrij and Sam Mann from Portsmouth University (UK) on Criteria-Based Content Analysis

Here’s the abstract:

Criteria-Based Content Analysis (CBCA) is a tool to assess the veracity of written statements, and is used as evidence in criminal courts in several countries in the world. CBCA scores are expected to be higher for truth tellers than for liars. The underlying assumption of CBCA is that (i) lying is cognitively more difficult than truth telling, and (ii) that liars are more concerned with the impression they make on others than truth tellers. However, these assumptions have not been tested to date. In the present experiment 80 participants (undergraduate students) lied or told the truth about an event. Afterwards, they completed a questionnaire measuring “cognitive load” and “tendency to control speech”. The interviews were transcribed and coded by trained CBCA raters. In agreement with CBCA assumptions, (i) truth tellers obtained higher scores than liars, (ii) liars experienced more cognitive load than truth tellers, and (iii) liars tried harder to control their speech. However, cognitive load and speech control were not correlated with CBCA scores in the predicted way.

Yes, I know I’m featuring rather a lot from Vrij and his colleagues, but they publish so darn frequently!

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Detecting Deception in Children: An Experimental Study of the Effect of Event Familiarity on CBCA Ratings

Iris Blandon-Gitlin, Kathy Pezdek, Martha Rogers and Laura Brodie
Law and Human Behavior 29(2), April 2005, pp 187-197

The CBCA is the most commonly used deception detection technique worldwide. Pezdek et al. (2004) used a quasi-experimental design to assess childrenrsquos accounts of a traumatic medical procedure; CBCA ratings were higher for descriptions of familiar than unfamiliar events. This study tested this effect using an experimental design and assessed the joint effect of familiarity and veracity on CBCA ratings.

Children described a true or a fabricated event. Half described a familiar event; half described an unfamiliar event. Two CBCA-trained judges rated transcripts of the descriptions. CBCA scores were more strongly influenced by the familiarity than the actual veracity of the event, and CBCA scores were significantly correlated with age. CBCA results were compared with results from other measures. Together with the results of K. Pezdek et al. (2004) these findings suggest that in its current form, CBCA is of limited utility as a credibility assessment tool.

Detecting Deception in Children: An Experimental Study of the Effect of Event Familiarity on CBCA Ratings

Iris Blandon-Gitlin, Kathy Pezdek, Martha Rogers and Laura Brodie
Law and Human Behavior 29(2), pp 187-197, April 2005

The CBCA is the most commonly used deception detection technique worldwide. Pezdek et al. (2004) used a quasi-experimental design to assess childrenrsquos accounts of a traumatic medical procedure; CBCA ratings were higher for descriptions of familiar than unfamiliar events. This study tested this effect using an experimental design and assessed the joint effect of familiarity and veracity on CBCA ratings. Children described a true or a fabricated event. Half described a familiar event; half described an unfamiliar event. Two CBCA-trained judges rated transcripts of the descriptions. CBCA scores were more strongly influenced by the familiarity than the actual veracity of the event, and CBCA scores were significantly correlated with age. CBCA results were compared with results from other measures. Together with the results of K. Pezdek et al. (2004) these findings suggest that in its current form, CBCA is of limited utility as a credibility assessment tool.

Training professional groups and lay persons to use CBCA to detect deception

Applied Cognitive Psychology Volume 18, Issue 7 , Pages 877 – 891

The effects of training professional groups and lay persons to use criteria-based content analysis to detect deception
Lucy Akehurst, Ray Bull, Aldert Vrij, Gunter Kohnken

This experiment was designed to assess, for the first time, the effects of training police officers, social workers and students in Criteria-Based Content Analysis (CBCA) in an attempt to increase lie detection accuracy. A within-subjects design was implemented. Participants rated the truthfulness of a maximum of four statements before training in CBCA and rated the truthfulness of a different set of four statements after training. The raters were only exposed to the written transcripts of the communicators. Two thirds of the statements utilized were truthful and one third were based on fabrications.

Before training, there were no significant differences in detection accuracy between the police officers (66% accuracy), the social workers (72% accuracy) and the students (56% accuracy). After training, the social workers were 77% accurate and significantly more accurate than the police officers (55%) and the students (61%). However, none of the three groups of raters significantly improved their lie detection accuracy after training, in fact, the police officers performed significantly poorer. Overall, police officers were significantly more confident than social workers and lay persons regardless of accuracy. Further, participants were most confident when labelling a statement truthful regardless of whether or not this was the correct decision.