Popular books on body language and even police manuals on interrogation have proposed a number of nonverbal indicators of deceit such as covering the mouth, self-touching, gaze aversion, blinking, etc.…But most scientific research on the matter suggests there is no basis for these claims. The fact of matter is that most people are poor lie-detectors and experiments have suggested that even professional lie-catchers aren’t much better at interpreting nonverbal behavior than the average Joe—police officers, judges, CIA officers, and FBI agents have all tested relatively average in terms of detecting deceit from nonverbal behavior. But there is research—conducted by Paul Ekman and colleagues—suggesting that there are people capable of detecting deceit at levels well above chance.
How to be one of them…
Forget the notion of specific set of behaviors as indicators of deceit and think about what it means to lie: deception=cognitive effort. Lies require effort because they entail nonexistent claims—details must be imagined and described as plausible—whereas the truth requires only the restatement of what is already known. The theory behind the polygraph is that the fear of being discovered causes emotional arousal, particularly anxiety, and the risk increases with elaboration. The implication is that the effort required to lie compounds upon itself, not only in terms of the need for creating a plausible elaboration of the account—the lie—but also with the need to control for anxiety. Remember though that anybody under suspicion is likely to feel anxiety so it’s not anxiety that concerns us the most—though it may be an indicator of deceit—it is effort that is most revealing.
Note: not all liars will feel anxiety; some may even feel self-gratification in their capability “out-smarting” others by deceit. Now back to cognitive effort…
Aldrit Vrij and his colleagues conducted an interesting experiment where they videotaped accounts of people either lying or telling the truth about an event they witnessed and then recruited police officers to determine the truth-tellers from the liars. There was a twist—the control group was asked to explicitly determine who was lying while the experimental group was asked to determine “who had to think the hardest.” The result is that police offers who were explicitly looking for lies failed to detect deception beyond chance but those who looked for the hard thinkers were very successful at identifying liars (though the didn’t realize that’s what they were doing). Vrij suggests that police officers who were looking for lies failed because they were biased by misconceptions such as liars fidget or avoid eye contact whereas in truth, liars tend to restrict body movements and make eye contact more intensely.
Rule 1: Forget those popular books on body language and don’t look for specific signs (e.g., looking away, stroking oneself, covering the mouth, etc.); rather, look for indications that the other person’s account is cognitively taxing. This rule alone, according to the research referenced above, will significantly enhance lie-detection ability.
Rule 2: Look for restricted expressiveness, especially in the context of the person’s normal expressiveness. A prominent theory of gesture is that they help the person making them visualize and regulate their own thoughts during interaction. An individual that is lying must either match their gestures to the lie or restrict their gestures so as not to reveal the lie. The theory of gesture as embodied cognition is supported by research indicating that liars tend to show less hand and arm movements thus indicating an attempt to restrain and control cognitive expression. But, again, people will have varying degrees of expressiveness so restricted behavior should be compared to the same person’s baseline behavior.
Rule 3: Make lying even more cognitively taxing than it already is; if lying requires mental effort then making it cognitively harder for the liar to account for his lie will give the lie-catcher greater opportunity to assess whether the suspect’s account is mentally taxing. The strategies here are really limitless but some ideas include (a.) ask the suspect his account of a potential lie when he is not expecting it—that is, when he doesn’t have the details scripted in his head and ready to state (b.) ask for details and further elaboration—the more details the greater the chances of an incongruence more challenging it is for liar (c.) look for possible points of contradiction and ask for elaboration (d.) restate the account differently but non-threateningly and ask if it is accurate (e.) restate a claim the subject made out of sequence and ask what happened before or after. Again, the lie catcher is looking for the degree of effort it takes for the subject to account for his claims. Note: there is a danger here in that the more times a liar accounts for his lie the more adept he will become at telling it and accounting for it; such threat should considered when confronting a suspected liar.
Rule 4: Look for inappropriate salesmanship. Contrary to popular belief, liars are more likely to look you harder in the eyes for which the theory is that they have a greater need to persuade. Because liars are motivated to disproportionately influence others’ perceptions, they will likely be particularly assertive and adamant. The lie-catcher can ask whether assertiveness and persuasiveness matches the subject’s baseline behavior but should also consider what is at stake. For instance, if an innocent individual is accused of murder they should be assertive with the declaration that they are not guilty but if someone asserts seemingly irrelevant facts out of an appropriate context, then there’s reason to ask questions.
Rule 5: Think like a social scientist. Do a videotaped interview when the stakes are high and then do a frame-by-frame analysis. The analysis of interaction and behavior is also cognitively taxing and an analyst or investigator won’t be able to keep track of every micro-level-event that occurred in the interaction; furthermore, the investigator will likely follow hunches—biases and heuristics—during the interview and will therefore over look much detail. Recording an interview allows the investigator opportunity to reflect on the interaction with greater objectivity and attention to detail. The analyst/investigator should examine the interview sequence-by-sequence making note of every utterance and gesture while asking what preceded it from which she will develop hypotheses and questions about the underlying cognitive motive for any statement or action. The analyst can then look for behavioral themes as well as incongruences and patterns that develop from the initial analysis and put forth an assessment that is based on behavioral details and contextualized to the broader interview.
Rule 6: Treat assumptions of lies as hypotheses not facts and look for corroboration. I’ve heard of a study where interrogators were given training on detecting lies and afterwards tested worse at lie detecting than before but demonstrated greater confidence in their (false) abilities. The lesson here in not to be overly confident: entertain other possibilities. Lie detection is indirect and requires that the lie cognitively and behaviorally alter the liar—when such changes are noted then it is appropriate to entertain the hypothesis that a lie is occurring but until corroborated with further evidence, the lie remains only a theory.