Lara Warmelink

The effect of question expectedness and experience on lying about intentions.

In recent years researchers have started to focus on lying about intentions (Granhag, 2010). In the present experiment participants were interviewed about their forthcoming trip. We tested the hypothesis that liars (N=43) compared to truth tellers (N=43) would give fewer details to unexpected questions about planning, transportation and the core event, but an equal amount or more detail to expected questions about the purpose of the trip. We also tested the hypothesis that participants who had previously experienced the intention (i.e., they had made such a trip before) would give more detail than those who had never experienced the intended action. The unexpected question hypothesis was supported, whereas the previous experience effect only emerged in interactions. The benefit of using different types of questions for lie detection purposes is discussed.

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.

Pseudoreplication : a widespread problem in primate communication research

Pseudoreplication (the pooling fallacy) is a widely acknowledged statistical error in the behavioural sciences. Taking a large number of data points from a small number of animals creates a false impression of a better representation of the population. Studies of communication may be particularly prone to artificially inflating the data set in this way, as the unit of interest (the facial expression, the call or the gesture) is a tempting unit of analysis. Primate communication studies (551) published in scientific journals from 1960 to 2008 were examined for the simplest form of pseudoreplication (taking more than one data point from each individual). Of the studies that used inferential statistics, 38% presented at least one case of pseudoreplicated data. An additional 16% did not provide enough information to rule out pseudoreplication. Generalized linear mixed models determined that one variable significantly increased the likelihood of pseudoreplication: using observational methods. Actual sample size (number of animals) and year of publication were not associated with pseudoreplication. The high prevalence of pseudoreplication in the primate communication research articles, and the fact that there has been no decline since key papers warned against pseudoreplication, demonstrates that the problem needs to be more actively addressed.

The Effects of Unexpected Questions on Detecting Familiar and Unfamiliar Lies

Previous research suggests that lie detection can be improved by asking the interviewee unexpected questions. The present experiment investigates the effect of two types of unexpected questions: background questions and detail questions, on detecting lies about topics with which the interviewee is (a) familiar or (b) unfamiliar. In this experiment, 66 participants read interviews in which interviewees answered background or detail questions, either truthfully or deceptively. Those who answered deceptively could be lying about a topic they were familiar with or about a topic they were unfamiliar with. The participants were asked to judge whether the interviewees were lying. The results revealed that background questions distinguished truths from both types of lies, while the detail questions distinguished truths from unfamiliar lies, but not from familiar lies. The implications of these findings are discussed.

Who should I look at? Eye contact during collective interviewing as a cue to deceit

Pairs of liars and pairs of truth tellers were interviewed and the amount of eye contact they made with the interviewer and each other was coded. Given that liars take their credibility less for granted than truth tellers, we expected liars to monitor the interviewer to see whether they were being believed, and to try harder to convince the interviewer that they were telling the truth. It was hypothesised that this monitoring would manifest itself through more eye contact with the interviewer and less eye contact with each other than in the case of truth tellers. A total of 43 pairs of participants took part in the experiment. Truth tellers had lunch in a nearby restaurant. Liars took some money from a purse, and were asked to pretend that instead of taking the money, they had been to a nearby restaurant together for lunch. Pairs of liars looked less at each other and displayed more eye contact with the interviewer than pairs of truth tellers. The implications of these findings are discussed.

Jumping the gun : faster response latencies to deceptive questions in a realistic scenario

Most theories of lie detection assume that lying increases cognitive load, resulting in longer response latencies during questioning. However, the studies supporting this theory are typically laboratory-based, in settings with no specific validity in security contexts. Consequently, using virtual reality (VR), we investigated how response latencies were influenced in an ecologically valid environment of interest to security professionals. In a highly realistic airport security terminal presented in VR, a security officer asked participants yes/no questions about their belongings. We found that liars actually responded more quickly to questions on which they were lying than to questions on which they were telling the truth. A control group, who answered the same questions but were not lying, answered equally quickly for all questions. We argue that this decrease in response time is possibly an unconscious reaction to questions on which individuals must answer deceptively. These results call into question the generalizability of previous research and highlight the importance of ecological validity when researching lie detection. These findings also uncover a new potential tool for enhancing lie detection in real-world scenarios.