Police officers ability to detect deception in high stakes situations and in repeated lie detection tests

Abstract

Thirty-seven police officers, not identified in previous research as belonging to groups that are superior in lie detection, attempted to detect truths and lies told by suspects during their videotaped police interviews. In order to measure consistency in their ability, the officers each participated in four different tests, each of which was on a different day. They were asked to indicate their confidence in being able to distinguish between truths and lies prior to the first test and after completing all four tests. We predicted that accuracy rates would be higher than those typically found in research with police officers; that good or poor performances on an individual test would be partly caused by luck, and, consequently, participants' accuracy scores were likely to progress towards the mean if their performance on all four tests was to be combined; and that officers would underestimate their own performance. These hypotheses were supported.In lie detection studies observers are typically shown videoclips from numerous liars and truth tellers and are asked after each clip to indicate whether the person was lying or telling the truth. Those studies often show individual differences in people's accuracy (Vrij, 2000a(Vrij, , 2004. The question is, how meaningful are those individual differences? The problem is that participants are typically tested only once. It therefore cannot be ruled out that a particular good or bad performance on the single lie detection task was just a matter of luck. This is a particularly relevant point in studies where attempts are made to unravel the strategies used by good lie detectors. In those studies lie detectors are, apart from making veracity judgements, asked to indicate which cues they paid attention to when making their veracity judgements

Reply scoring and reporting: A response to bond (2008)

“…DePaulo (a frequent co-author on Bond's recent publications) reported that when the stakes are low it is harder to tell who is lying (DePaulo, Lanier, & Davis, 1983). Others since us, who also studied lying when the incentives and punishment can be presumed to be very high, have also reported higher than typical accuracy in judging deception, consistent with our reasoning and prior findings (Vrij, Mann, Robbins, & Robinson, 2006).…”

High stakes lies: police and non-police accuracy in detecting deception

“…The few studies that have investigated this have produced reasonably consistent results, which differ from metaanalytic findings of low stakes deception detection (Bond & DePaulo, 2006), and suggest that people may be able to detect deception with accuracy substantially above chance levels: in a series of studies using videos of police interviews with suspects as stimulus materials Mann, Vrij & Bull, 2004Vrij & Mann, 2001a;Vrij, Mann, Robbins & Robinson, 2006), police officers' credibility judgements were consistently accurate at rates well above chance levels, at 68%, 65%, 69%, 64% and 72% respectively. These relatively high accuracy rates are important, as previous studies, using low stakes stimulus materials, have suggested that police officers are no more accurate than laypersons at detecting deception (for example, DePaulo & Pfeifer, 1986;Ekman & O'Sullivan, 1991;Meissner & Kassin, 2002).…”

“…participants observed honest and deceptive individuals. In the majority of previous research investigating deception in high stakes situations, a within subjects stimulus materials design has been used Mann et al, 2004Vrij & Mann, 2001a;Vrij et al, 2006). In these studies, honest and deceptive sections of communications by individuals guilty of committing various crimes are compared, and this within subjects method is limited as it negates the possibility of examining the individuals holistically; i.e.…”

Prescription fraud: A comparison of pharmacists' and laypersons' perceptions of suspicious prescription presentation behaviour

“…The sample size of pharmacists limited the study with respect to statistical power, as the low sample size may have prevented some significant results, particularly with the use of the Bonferroni correction. However, other studies in the deception detection field have used similarly sized samples of experts (see Vrij et al, 2006;Vrij and Mann, 2001;Lakhani and Taylor, 2002). There was also the possibility of selection effects, whereby the most proactive and interested pharmacists took the time to complete the survey.…”