The use, distribution or reproduction in other forums is permitted, provided the original author s and the copyright owner s are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Abstract We have been reliably informed by practitioners that police officers and intelligence officers across the world have started to use the Model Statement lie detection technique. In this article we introduce this technique. We describe why it works, report the empirical evidence that it works, and outline how to use it.
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The use, distribution or reproduction in other forums is permitted, provided the original author s and the copyright owner s are credited and that the original publication in this journal is cited, in accordance with accepted academic practice.
No use, distribution or reproduction is permitted which does not comply with these terms. Abstract We have been reliably informed by practitioners that police officers and intelligence officers across the world have started to use the Model Statement lie detection technique. In this article we introduce this technique. We describe why it works, report the empirical evidence that it works, and outline how to use it.
Research examining the Model Statement only started recently and more research is required. We give suggestions for future research with the technique. The Model Statement technique is one of many recently developed verbal lie detection methods.
We start this article with a short overview of the—in our view- most promising recent developments in verbal lie detection before turning our attention to the Model Statement technique. Keywords: deception, interview, model statement, encouraging interviewees to say more, lie detection Verbal lie detection DePaulo et al.
This relative weakness of nonverbal cues to deceit could at least in part be explained when taking into account the strategies truth tellers and liars use when attempting to make a convincing impression on others.
Truth tellers and liars employ similar strategies regarding nonverbal behavior: Both try to suppress signs of nervousness and attempt to replace them with signs that will create the impression of being honest, such as looking conversation partners into their eyes and avoiding fidgeting scratching head, wrists etc. In contrast, truth tellers and liars use different strategies regarding verbal behavior. As a consequence, truthful stories often include more details than deceptive stories 1 , 8.
Because researchers found nonverbal cues to be ineffective to detect deception, they refocused their efforts to focus on verbal cues. Particularly, they have tried to elicit or enhance verbal cues through specific interview techniques that exploit the different verbal strategies that truth tellers and liars employ 9. In our view, four of these efforts have shown the best results or the best potential in terms of lie detection 10 , 11 : a The Strategic Use of Evidence, b Assessment Criteria Indicative of Deception, c the Verifiability Approach, and d Cognitive Credibility Assessment, to which the Model Statement technique belongs.
We outline these approaches briefly and refer to Vrij 10 , 11 and Vrij and Fisher 12 for further details. Strategic use of evidence SUE The aim of the SUE technique is to exploit the different strategies truth tellers and liars employ in interviews, particularly the difference in between forthcoming truth tellers and avoiding mentioning incriminating details liars 6 , In addition, during an interview liars sometimes start to realize that the interviewer may have some evidence against them i.
Liars then often change their statement and provide an innocent explanation for the evidence i. In ACID, truth tellers and liars provide an initial free recall followed by instructions that stimulate communication and aid memory ACID research has shown that, amongst other findings, truth tellers report more additional information after the initial free recall than liars 16 , On the one hand, liars prefer to provide many details. On the other hand, liars do not wish to mention too many details.
The more details they provide, the more opportunity they give to investigators to check these details and to discover their lies A strategy that incorporates both seemingly conflicting goals is to provide details that cannot be verified Indeed, research has shown that truth tellers typically report more details that can be checked than liars Checkable details are activities that someone claims to have carried out or was witnessed by a named person, or activities that someone claimed was recorded on CCTV.
The effect that truth tellers report more checkable details than liars becomes stronger when interviewees are instructed to try to include details in their statement that the investigator can verify. Following such a request, truth tellers add more checkable details in their accounts than liars 22 , Cognitive credibility assessment CCA The CCA technique comprises three elements: i Imposing cognitive load; ii Asking unexpected questions, and iii Encouraging interviewees to say more 24 , Investigators can exploit this difference in cognitive load by making additional requests that will further increase the cognitive load truth tellers and liars experience [such as gripping an object while telling a story, 27 ].
Liars often prepare themselves for interviews by planning answers to possible questions 7. This planning makes sense as planned answers often contain fewer cues to deceit than spontaneous answers 1. However, there is a weakness: Liars cannot know which questions will be asked. Investigators can exploit this weakness by asking a mixture of anticipated and unanticipated questions. Liars find it easier to answer the anticipated questions than the unanticipated questions, because they can give their planned answers to the former but not to the latter For truth tellers, the difficulty in answering anticipated and unanticipated questions should be less pronounced.
The most straightforward application of this technique is by interviewing pairs of suspects individually and comparing their answers to the expected and unexpected questions.
Pairs of truth tellers showed similar overlap in their answers to expected questions as pairs of liars, but the pairs of truth tellers showed more overlap in their answers to unexpected questions than pairs of liars 30 , Another comparison can also be made: Comparing the overlap between expected and unexpected questions within pairs of truth tellers and within pairs of liars. Pairs of truth tellers showed a similar overlap in their answers to the expected and unexpected questions, whereas pairs of liars showed more overlap in their answers to the expected questions than in their answers to the unexpected questions In interview settings, truth tellers typically do not provide spontaneously all the information they hold in their memory 32 , There are two reasons for this, a cognitive reason and a social reason.
Regarding the cognitive reason: Interviewees are unable to retrieve spontaneously all the information from their memory. Memory recall can be enhanced by using mnemonics of which asking interviewees to sketch while talking is an example Sketching while narrating elicits additional information in truth tellers 34 — Vrij et al. Second, sketching is a visual output which makes it more compatible with visually experienced events than the traditional oral output.
Sketching facilitates recalling visual or spatial information 15 , which is often the type of information interviewees discuss. Third, making a sketch is a time consuming activity. Spatial information is not automatically given in a verbal response, because someone can just report who were present and which objects were present without reporting their locations In the only deception experiment to date in which participants were asked to sketch while narrating 37 , the difference in truth tellers reporting more additional details than liars was greater in the sketch condition than in the control condition.
The second reason why truth tellers typically do not provide spontaneously all the information they know in interview settings is a social reason: People are uncertain what and how much information they are expected to provide. The Model Statement technique addresses this social reason. The model statement technique In daily life situations social rules imply that people do not report all the information they know.
Of course, interviewees will realize in formal interview settings that they need to provide more information than a few words or sentences, but they still do not know how much detail they are expected to provide.
The Model Statement works as a social comparison 40 , 41 and has shown to raise the expectations amongst both truth tellers and liars about how much information they are expected to It is probably easier for people to follow concrete examples than abstract instructions A Model Statement does not just elicit information, it can also be used for lie detection if certain dependent variables are analyzed.
In the first two Model Statement deception studies ever published, the Model Statement facilitated the elicitation of information 39 , This exact pattern of results has been replicated in six out of seven ensuing studies 42 , 43 , 45 — 49 , but see Porter et al.
In other words, the Model Statement technique elicits more information in both truth tellers and liars, but cannot distinguish between truth tellers and liars based on the total amount of information. For the Model Statement technique to work as a lie detection tool it is important to consider the quality rather than the quantity of information that is reported.
The first Model Statement deception study 39 already hinted at this: Although truth tellers and liars provided a similar amount of information after exposure to a Model Statement, the information provided by truth tellers sounded more plausible than that of liars.
That the quality of details rather than the quantity of details distinguish truth tellers from liars makes sense. Both truth tellers and liars realize after exposure to a Model Statement that they are expected to provide many details The amount of details is thus unlikely to distinguish between the two groups.
The type of detail becomes relevant because it takes into account the different cognitive abilities of truth tellers and liars and the different strategies they use to appear convincing. Studies to date gave insight into two types of detail that could distinguish truth tellers from liars after exposure to a Model Statement, the number of complications 37 , 49 and the number of peripheral details 43 that were reported.
Complications occur more often in truthful statements than in deceptive statements 8 , In interviews, liars prefer to keep their stories simple 7 , but adding complications makes the story more complex.
A Model Statement increases the number of complications interviewees report, particularly in truth tellers 37 , Complications are often not about key aspects of the activities that someone describes, and the story can be well understood without reporting the complications.
Take for example, when someone describes traveling to a holiday destination. All sorts of complications that happen en route to a holiday destination are not necessary to understand the travel to the holiday destination someone forgot to bring a valuable item; taxi turned up late; traffic on the road; airplane delayed; late gate change at the airport.
Therefore, truth tellers may leave at least some of them out when they are not exposed to a Model Statement. Liars are reluctant to provide complications in order to keep their story simple. As a result, truth tellers are more likely than liars to report more complications after being exposed to a Model Statement. Core details are details that, if changed, can result in changes in the basic and most important part of the story; details that have no such impact are considered peripheral Thus, if someone describes attending an Adele pop concert, all details about the actual concert are core details whereas information about drinks in the pub before and after the concert, are peripheral details.
Both truth tellers and liars realize that they need to provide more details after exposure to a Model Statement Truth tellers, who have actually experienced an event e. For liars, who have not experienced an event e. It is difficult because they have to make up information and it is risky because the information may provide leads to investigators that they can check. Thus, liars may avoid providing too many core details in an attempt to minimize the risk of presenting incriminating information 6 , 21 , but may compensate this by providing peripheral details in an attempt to provide a sufficient amount of detail.
In the only Model Statement deception experiment distinguishing between core and peripheral details to date, the latter assumption was supported: In the Model Statement present condition liars reported more peripheral details than truth tellers, whereas no difference in peripheral details emerged in the control condition How to use a model statement in real life We believe that the Model Statement technique should be used as a within-subjects technique, as employed by Leal et al. Investigators should then listen to the number of new complications reported in the second recall and the amount of new peripheral information reported in the second recall.
Three practical elements merit attention First, use a within-subjects structure when applying the Model Statement technique. Within-subjects comparisons are better for lie detection purposes than between-subjects comparisons In a between-subjects comparison, the interviewee would be asked to report the event only once and to do this after exposure to the Model Statement.
In a within-subjects comparison, it does not matter how detailed an initial answer is or how many complications someone initially provides which is largely influenced by personality, situation and preparedness. The only relevant measure is the number of peripheral details and complications that are added more likely to be influenced by veracity. In our research, we use a words Model Statement in which a young man describes his experiences when attending a Formula 2 motor race, commencing where the drivers go to their grid position prior to the start of the race.
This is an atypical event that does not give interviewees the opportunity to copy details. Third, our Model Statement is an authentic experience the person really attended a Formula 2 motor race , which we think is important. True experiences sound more realistic than made-up experiences and are therefore more powerful.
Detecting Lies and Deceit : Pitfalls and Opportunities
Why do people lie? Do gender and personality differences affect how people lie? How can lies be detected? This revised edition provides an up-to-date account of deception research and discusses the working and efficacy of the most commonly used lie detection tools, including: Behaviour Why do people lie? This revised edition provides an up-to-date account of deception research and discusses the working and efficacy of the most commonly used lie detection tools, including: Behaviour Analysis InterviewStatement Validity AssessmentReality MonitoringScientific Content AnalysisSeveral different polygraph testsVoice Stress AnalysisThermal ImagingEEG-PFunctional Magnetic Resonance Imaging fMRI All three aspects of deception are covered: nonverbal cues, speech and written statement analysis and neuro physiological responses.