Lying about intentions

  • Lara Natasja Warmelink

Student thesis: Doctoral Thesis


This thesis aims to explore whether lying about intentions can be detected using the same methods that are used to detect other types of lie. Part I, the introduction, contains a literature review of research into future thinking and intentions.
In Part II non-verbal cues and thermal imaging are investigated as cues to deception. In Experiment 1 participants of twelve different ethnicities were interviewed at an airport about their forthcoming trip. Half of the participants were instructed to answer truthfully, the other half to answer deceptively. The participants’ veracity affected only three of the 17 non-verbal cues: struggling, thinking hard and controlling behaviour. These cues were reduced to two factors, cognitive load and animation. These two factors could correctly classify 52.3% of truth tellers and 62.6% of liars. The thermal imaging showed that liars tended to get warmer during the interview, while the truth tellers’ temperatures remained constant. This temperature rise was a cue to deception at above chance rates.
In Part III two experiments are described, investigating verbal cues to deceit in longer and shorter interviews. In Experiment 2 participants were interviewed, answering truthfully or deceptively, about a forthcoming trip. The interview contained general questions that were expected by the participants and three types of unexpected questions. Half of the participants had been to the travel destination previously, while the other half had not been there. The results showed that truth tellers generated more details on the unexpected questions than liars, while liars provided more details on expected questions than truth tellers. This pattern was more pronounced with participants who had been to their travel destination before than for those who had never been to that destination. A positive predictive value of .69 (truth) and a negative predictive value of .75 (lie) were obtained. Experiment 3 investigated verbal cues to deceit in a short one question interview about a forthcoming trip. The interview question was asked in two forms, one prompting for time detail and one control. The results showed that truth tellers and those answering the time prompting question were more likely to provide temporal information. The results showed that 47.6% of truth tellers and 81% of liars could be classified correctly on the basis of the time prompt question.
Part IV investigated reaction times as a cue to deception. In Experiment 4, participants were asked to perform a mission, either immediately or two weeks later. Half of the participants was instructed to answer any questions asked by experimenters en route truthfully, the other half was asked to answer deceptively. Using a computer, participants classified adjectives as positive or negative and were primed by words related to the real intention of truth tellers (to buy a present), which was also the cover story for liars. Contrary to the hypothesis, in the immediate condition liars answered faster on positive than negative adjectives, while the truth tellers responded equally fast to both adjectives. In the delayed condition no difference was found between truth tellers and liars.
Part V presents the general discussion. The main findings of the thesis are summarised, practical and theoretical implications are discussed, the methodological and ethical limitations are considered and ideas for future research are given. Overall, the conclusion of the thesis is that false intentions contain cues to deceit that observers should be able to spot.
Date of AwardMay 2012
Original languageEnglish
Awarding Institution
  • University of Portsmouth
SupervisorAldert Vrij (Supervisor) & Sam Mann (Supervisor)

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