Systematic errors (biases) in applying verbal lie detection tools: richness in detail as a test case

Meta-Research Perspectives on Verbal Lie Detection

Verbal lie detection (VLD) research, conducted mainly in the cognitive sciences, examines content-based indicators that differ between truth-tellers and lie-tellers. Following the meta-research approach (examination of the research itself), the current paper aimed to ascertain the current status of VLD research across three components: the search for VLD indicators, VLD coding, and VLD research tracks. It highlights several issues that challenge VLD research; these are discussed, along with suggestions for how to address them. This scrutiny may contribute to a further advancement of the field of VLD research and, as a result, an improvement of VLD practices.

Do liars really remember what they lied upon? The impact of fabrication on memory

The present experiment aimed to examine how fabrication can affect memory. In particular, we examined whether different types of fabrication can lead to different mnemonic effects. A sample of 159 participants watched a video of a robbery and subsequently answered some questions about it. Participants were divided into three conditions: one group was instructed to tell the truth (i.e., truth-telling group), while the other two groups were instructed to lie either by partially distorting details (i.e., distortion group) or by completely making up wrong details of the event seen in the video (i.e., fabrication group). Two days later, participants completed a final memory test where they honestly answered recognition and recall questions concerning: (i) memory for the video and (ii) memory for having discussed details during the interview. Results showed that different types of fabrication affect liars' memory differently. Fabricators reported an undermining of memory for the event, whereas those who partially distorted details reported a higher impairment for the interview. Our findings showed that the effects of lying on liars' memory might be determined by the cognitive resources required to lie.

The effects of sketching while narrating on information elicitation and deception detection in multiple interviews

Sketching while narrating is effective for eliciting information and veracity cues in single interviews. In the current research, we tested this technique in multiple interviews. Participants were interviewed three times over three weeks about a genuine (truth tellers) or a fabricated (lie tellers) memorable event. They sketched while narrating in Week 1, Week 2, Weeks 1 and 2, or not at all (verbal statement only). Statements were coded for total, core, peripheral, and common knowledge details, self-handicapping strategies, complications, plausibility, and proportions of complications and core details. In the third interview and across interviews, the Sketch instruction resulted in a higher proportion of core details. Truth tellers reported more total and core details and complications and fewer common knowledge details and exhibited a higher proportion of complications than lie tellers. Truth tellers' stories also sounded more plausible than lie tellers' stories. The interaction effects were not significant. Thus, sketching while narrating seemed to have a similar effect on truth tellers and lie tellers in the current study.

Amplifying recall after delays via initial interviewing: Inoculating truth-tellers' memory as a function of encoding quality

Typically, truth-tellers report more detailed statements when interviewed immediately, compared to after delays (displaying forgetting), whereas liars report statements containing similar amounts of detail when interviewed immediately or after a delay (displaying a metacognitive error). Accordingly, the diagnostic utility of the 'richness-of-detail' cue is reduced after delays. We investigated if initial interviewing can facilitate lie-detection using the richness-of-detail cue in sub-optimal memorial conditions, that is, when (i) interviewing occurred after a three-week delay and (ii) truth-teller's attention during encoding was manipulated. Participants (n = 152) witnessed an interaction, that was meaningful to (and intentionally encoded by) liars (n = 50) and half of truth-tellers (n = 51), but meaningless (and incidentally encoded by) the remaining truth-tellers (n = 51). Participants were interviewed after three weeks. Half of the intentional liars and half of the intentional and incidental truth-tellers were also interviewed immediately (initial interview-present condition), whereas the remaining participants received no immediate interview (initial interview-absent condition). Results showed intentional and incidental truth-tellers reported after three weeks more detail in the initial interview-present (versus absent) condition, whereas intentional liars' statements were unaffected by initial interviewing condition. After three weeks, more intentional liars and intentional truth-tellers were correctly distinguished in the initial interview-present (versus absent) condition.

The effects of a model statement on information elicitation and deception detection in multiple interviews

Researchers started developing interview techniques to enhance deception detection in forensic settings. One of those techniques is the Model Statement, which has been shown to be effective for eliciting information and cues to deception in single interviews. In the current research, we focused on the effect of the Model Statement in multiple interviews. Participants (N = 243) were interviewed three times-each time one week apart-about a genuine (truth tellers) or fabricated (lie tellers) memorable event. They listened to a Model Statement at Time 1, Time 2, Times 1 and 2, or not at all. Hypotheses focused on participants' verbal reports at Time 3 and on unique details provided across the three interviews. In both instances, truth tellers provided more core and total details and complications and fewer common knowledge details and self-handicapping strategies and obtained higher proportion scores of (i) complications and (ii) core details than lie tellers. Complications and proportion of complications were the most diagnostic cues. The Model Statement was effective only when presented at Time 1, resulting in more common knowledge details. No Veracity × Model Statement interaction effects emerged.

Applying the verifiability approach to deception detection in alibi witness situations

The application of alibi witness scenarios to deception detection has been overlooked. Experiment 1 was a study of the verifiability approach in which truth-telling pairs completed a mission together, whereas in lying pairs one individual completed this mission alone and the other individual committed a mock theft. All pairs were instructed to convince the interviewer that they completed the mission together by writing individual statements on their own followed by a collective statement together as a pair. In the individual statements, truth-telling pairs provided more checkable details that demonstrated they completed the mission together than lying pairs, whereas lying pairs provided more uncheckable details than truth-telling pairs. The collective statements made truth-telling pairs provide significantly more checkable details that demonstrated they were together in comparison to the individual statements, whereas no effect was obtained for lying pairs. Receiver Operating Characteristic curves revealed high accuracy rates for discriminating between truths and lies using the verifiability approach across all statement types. Experiment 2 was a lie detection study whereby observers' abilities to discriminate between truths and lies using the verifiability approach were examined. This revealed that applying the verifiability approach to collective statements improved observers' ability to accurately detect deceit. We suggest that the verifiability approach could be used as a lie detection technique and that law enforcement policies should consider implementing collective interviewing.

Detecting false intentions using unanticipated questions

The present study investigated whether measurable verbal differences occur when people vocalize their true and false intentions. To test potential differences, we used an experimental set-up where liars planned a criminal act (i.e., installing a virus on a network computer) and truth-tellers a non-criminal act (i.e., installing a new presentation program "SlideDog" on a network computer). Before they could carry out these acts, a confederate intercepted the participant and interviewed them about their intentions and the planning phase by using both anticipated and unanticipated questions. Liars used a cover story to mask their criminal intentions while truth-tellers told the entire truth. In contrast to our hypotheses, both human and automated coding did not show any evidence that liars and truth-tellers differed in plausibility or detailedness. Furthermore, results showed that asking unanticipated questions resulted in lengthier answers than anticipated questions. These results are in line with the mixed findings in the intention literature and suggest that plausibility and detailedness are less diagnostic cues for deception about intentions.

Lie prevalence, lie characteristics and strategies of self-reported good liars

Meta-analytic findings indicate that the success of unmasking a deceptive interaction relies more on the performance of the liar than on that of the lie detector. Despite this finding, the lie characteristics and strategies of deception that enable good liars to evade detection are largely unknown. We conducted a survey (n = 194) to explore the association between laypeople’s self-reported ability to deceive on the one hand, and their lie prevalence, characteristics, and deception strategies in daily life on the other. Higher self-reported ratings of deception ability were positively correlated with self-reports of telling more lies per day, telling inconsequential lies, lying to colleagues and friends, and communicating lies via face-to-face interactions. We also observed that self-reported good liars highly relied on verbal strategies of deception and they most commonly reported to i) embed their lies into truthful information, ii) keep the statement clear and simple, and iii) provide a plausible account. This study provides a starting point for future research exploring the meta-cognitions and patterns of skilled liars who may be most likely to evade detection.

Amplifying deceivers' flawed metacognition: Encouraging disclosures after delays with a model statement

Truth tellers provide less detail in delayed than in immediate interviews (likely due to forgetting), whereas liars provide similar amounts of detail in immediate and delayed interviews (displaying a metacognitive stability bias effect). We examined whether liar's flawed metacognition after delays could be exploited by encouraging interviewees to provide more detail via a Model Statement. Truthful and deceptive participants were interviewed immediately (n = 78) or after a three-week delay (n = 78). Half the participants in each condition listened to a Model Statement before questioning. In the Immediate condition, truth tellers provided more details than liars. This pattern was unaffected by the Model Statement. In the Delayed condition, truth tellers and liars provided a similar amount of detail in the Model Statement-absent condition, whereas in the Model Statement-present condition, liars provided more details than truth tellers.

Detecting Lies via a Theme-Selection Strategy

Most of deception research has focused on past events that were either completely truthful or a complete fabrication. However, people often tell a mixture of truths and lies. This could enable investigators to make within-subjects comparisons between different themes discussed in one interview, which we examined in the current experiment. Seventy-three participants took part in the experiment and were asked to either tell the truth about two themes, or to tell the truth about one theme and lie about the second theme in a HUMINT setting. Results showed that examining the differences in the amount of detail provided by the interviewees for each theme- obtained through a Theme-Selection strategy (a within-subjects measure)- yielded stronger results than examining differences between truth tellers and liars based on the entire interview without accounting for themes (between-subjects measure). The present study therefore highlighted the effectiveness of within-subjects measurements to both discriminate truth tellers from liars and to discover which section of a statement is false.

Using the model statement to elicit information and cues to deceit in interpreter-based interviews

We examined how the presence of an interpreter during an interview affects eliciting information and cues to deceit, while using a method that encourages interviewees to provide more detail (model statement, MS). A total of 199 Hispanic, Korean and Russian participants were interviewed either in their own native language without an interpreter, or through an interpreter. Interviewees either lied or told the truth about a trip they made during the last twelve months. Half of the participants listened to a MS at the beginning of the interview. The dependent variables were 'detail', 'complications', 'common knowledge details', 'self-handicapping strategies' and 'ratio of complications'. In the MS-absent condition, the interviews resulted in less detail when an interpreter was present than when an interpreter was absent. In the MS-present condition, the interviews resulted in a similar amount of detail in the interpreter present and absent conditions. Truthful statements included more complications and fewer common knowledge details and self-handicapping strategies than deceptive statements, and the ratio of complications was higher for truth tellers than liars. The MS strengthened these results, whereas an interpreter had no effect on these results.