Sharon Leal

Outsmarting the liars The benefit of asking unanticipated questions

We hypothesised that the responses of pairs of liars would correspond less with each other than would responses of pairs of truth tellers, but only when the responses are given to unanticipated questions. Liars and truth tellers were interviewed individually about having had lunch together in a restaurant. The interviewer asked typical opening questions which we expected the liars to anticipate, followed by questions about spatial and/or temporal information which we expected suspects not to anticipate, and also a request to draw the layout of the restaurant. The results supported the hypothesis, and based on correspondence in responses to the unanticipated questions, up to 80% of liars and truth tellers could be correctly classified, particularly when assessing drawings.

Detecting deception by manipulating cognitive load

Concern with crime and terrorism makes it increasingly important to be able to detect lying. Most lie detection tools used to date are arousal-based protocols. The majority of these protocols are based on the assumption that, because of their fear of being caught, liars will be more aroused when answering key relevant questions (‘Did you steal the money?’) than when answering comparison questions. According to the US National Research Councils well-documented report [1], however, this premise is theoretically weak. Liars do not necessarily reveal more signs of arousal when answering key questions. Conversely, truth tellers might be anxious and hence show signs of arousal when answering key questions.

Outsmarting the Liars: Toward a Cognitive Lie Detection Approach

Five decades of lie detection research have shown that people’s ability to detect deception by observing behavior and listening to speech is limited. The problem is that cues to deception are typically faint and unreliable. The aim for interviewers, therefore, is to ask questions that actively elicit and amplify verbal and nonverbal cues to deceit. We present an innovative lie detection perspective based on cognitive load, demonstrating that it is possible to ask questions that raise cognitive load more in liars than in truth tellers. This cognitive lie detection perspective consists of two approaches. The imposing-cognitive-load approach aims to make the interview setting more difficult for interviewees. We argue that this affects liars more than truth tellers, resulting in more, and more blatant, cues to deceit. The strategic-questioning approach examines different ways of questioning that elicit the most differential responses between truth tellers and liars.

Using sketch drawing to induce inconsistency in liars

Purpose. Consistency as a cue to detecting deception was tested in two experiments using sketch drawing and verbal reports in repeated interviews. Liars were expected to be less consistent than truth-tellers.Methods. In Expt 1, 80 undergraduate students reported truthfully or deceptively about an alleged lunch date - they sketched the layout of the restaurant and then answered spatial questions about objects in the restaurant. Ratings were given for the consistency between sketches and verbal reports. In Expt 2, 34 undergraduate students reported truthfully or deceptively about completing a series of unrelated tasks - they answered spatial questions about objects in a room and then sketched the layout of the room. Proportions were calculated for the consistency between verbal reports and sketches.Results. Expt 1. Liars were rated as less consistent than truth-tellers. Up to 80% of truth-tellers and 70% of liars could be correctly classified. Expt 2. Liars were less consistent than truth-tellers on consistency proportions. Up to 100% of truth-tellers and 77% of liars could be correctly classified.Conclusions. Using sketches to induce inconsistency may be a reliable, resource efficient way to help investigators detect deception. Language: en

Lying about flying: the first experiment to detect false intent

This article reports the results of, to our knowledge, the first ever experiment to investigate lying about intentions. Sixty passengers in an airport departure hall told the truth or lied about their forthcoming trip in an interview that comprised nine questions. The interviews were transcribed and raters coded the amount of detail in, and the plausibility of, the answers. Raters also coded whether the transcripts included contradictions and spontaneous corrections. Liars’ answers were less plausible than truth tellers’ answers but did not differ in terms of detail. Liars also included more contradictions and fewer spontaneous corrections in their answers. A total of 72% of truth tellers and 74% of liars were detected on the basis of these variables. We discuss the implications of the findings together with the limitations of the experiment and ideas for future research.

Imposing cognitive load to elicit cues to deceit: inducing the reverse order technique naturally

Abstract In two experiments, we tested the hypotheses that (i) the difference between lying and truth telling will be greater when respondents report their stories in reverse order than in chronological order, and (ii) instructing respondents to recall their stories in reverse order will facilitate detecting deception. In Experiment 1, 31 professionals told the truth and lied about a route they took and did this by describing the route in chronological order and reverse order. The reverse-order answers contained more prominent cues to deceit than did the chronological-order answers. In Experiment 2, 68 observers read the transcripts of the verbal statements given in Experiment 1 and made veracity judgements. Observers detected deception better when judging the routes that respondents had described in reverse order than in chronological order. We recommend the use of the reverse order technique as a tool to detect deceit.

Thermal Imaging as a Lie Detection Tool at Airports

We tested the accuracy of thermal imaging as a lie detection tool in airport screening. Fifty-one passengers in an international airport departure hall told the truth or lied about their forthcoming trip in an interview. Their skin temperature was recorded via a thermal imaging camera. Liars’ skin temperature rose significantly during the interview, whereas truth tellers’ skin temperature remained constant. On the basis of these different patterns, 64% of truth tellers and 69% of liars were classified correctly. The interviewers made veracity judgements independently from the thermal recordings. The interviewers outperformed the thermal recordings and classified 72% of truth tellers and 77% of liars correctly. Accuracy rates based on the combination of thermal imaging scores and interviewers’ judgements were the same as accuracy rates based on interviewers’ judgements alone. Implications of the findings for the suitability of thermal imaging as a lie detection tool in airports are discussed.

Getting into the Minds of Pairs of Liars and Truth Tellers: An Examination of Their Strategies

We examined the strategies used by 20 pairs of liars and 20 pairs of truth tellers when they were given the opportunity to prepare themselves for an interview in which they would be questioned about their whereabouts during a given period of time. More lying than truth telling pairs prepared themselves for the interviews. The truth tellers and liars who did prepare themselves used different verbal strategies but the same nonverbal strategies. Regarding verbal strategies, truth tellers were predominantly concerned with telling everything they could remember. In contrast, liars thought of answers they could give to possible questions but also decided to be vague so that they would not contradict each other. Regarding nonverbal strategies, both truth tellers and liars tried to suppress nervous behaviours. These findings explain why truth tellers are typically more detailed than liars but also why liars are typically equally consistent as truth tellers, at least when answering questions they have anticipated. Implications for interview techniques to detect deceit are discussed.

Is anyone there? Drawings as a tool to detect deceit in occupation interviews

Abstract In the present experiment 17 truth tellers and 16 liars were asked to verbally describe and sketch their workplace. We measured (i) the amount of detail included in the verbal description/sketch; (ii) the plausibility of the verbal description/sketch; (iii) the number of people verbally described/sketched; and (iv) the level of detail in which these people were verbally described/sketched. Differences between truth tellers and liars emerged on all four variables in the drawings whereas only one difference (the number of people described) emerged in the verbal accounts. Two possible explanations for the efficiency of drawings as a veracity assessment tool in this experiment are discussed. First, the request to sketch came as a surprise to participants and, second, sketching creates a unique problem for liars: more so than a verbal request, the request to sketch forces an interviewee to convey spatial information.

The time of the crime: Cognitively induced tonic arousal suppression when lying in a free recall context

Previous research has shown that suspects in real-life interviews do not display stereotypical signs of nervous behaviours, even though they may be experiencing high detection anxiety. We hypothesised that these suspects may have experienced cognitive load when lying and that this cognitive load reduced their tonic arousal, which suppressed signs of nervousness. We conducted two experiments to test this hypothesis. Tonic electrodermal arousal and blink rate were examined during task-induced (Experiment 1) and deception-induced cognitive load (Experiment 2). Both increased cognitive difficulty and deception resulted in decreased tonic arousal and blinking. This demonstrated for the first time that when lying results in heightened levels of cognitive load, signs of nervousness are decreased. We discuss implications for detecting deception and more wide-ranging phenomena related to emotional behaviour.