Theoretical perspectives on non-verbal cues to deception
What are the characteristics of truthful or false communication? Vrij, Edward, Roberts and Bull (2000): Three possible ways to detect lying – (a)nonverbal communication (body language, smiling, gaze aversion) (b)Vocal behaviour (speech rate, pitch) (c)physiological responses. Vrij (2000): Problem is that none of these is unequivocal evidence of lying.
Ekman (1985/1992): Two kinds of cue to deception – Thinking cues – inconsistencies in the story itself, or an over-rehearsed story. May speak more slowly. Feeling cues – fear (and also excitement) produces higher-pitched voice, more speech errors.
Zuckerman, DePaulo and Rosenthal (1981): Three factors affect a liar’s nonverbal behaviour. (a)Emotional reactions of guilt, fear or excitement (gaze aversion, decreased illustrators, physiological arousal indicators such as blinking, self-touching, speech hesitations and errors, raised pitch) (b)Cognitive effort (c)Attempted behavioural control (decreased movement, lack of spontaneity; unnaturally measured speech rate)
DePaulo (1992): Self-presentational perspective. Truth-tellers and liars have much in common – nervous truth-tellers may resemble liars. (a)Liars may endorse their self-presentations less (seem less involved). (b)Liars take their credibility less for granted, and are more concerned about the impression they make on others.
Buller and Burgoon (1996): Interpersonal Deception Theory (IDT). Liars have to perform numerous communication tasks simultaneously – (a)produce credible verbal and non-verbal behaviour; (b)attend to their audience to ensure they are still being believed; (c)manage their emotions; (d)manage normal conversational processes. Audience’s behaviour affects the liar too; liars may respond with “honest behaviour”.
What characteristics distinguish truth-tellers from liars?
Myths about liars: Akehurst, Kohnken, Vrij and Bull (1996): Gaze aversion, smiling, blinking and self- manipulations all widely believed to accompany lying. None of these is actually related to lying. (Shifting position (fidgeting) is also widely believed to reflect lying; but evidence is equivocal).
DePaulo et al (2003): meta-analysis of genuine characteristics of liars: More dilated pupils. Appear more tense physically and vocally. Chin raised. Sound more ambivalent and less involved. Higher pitched voice. Repeat words and sentences more. Move arms, hands, fingers, legs and feet less. However - behaviours indicative of lying can be indicative of other states too (e.g. anxiety, ambivalence)
Kraut (1980): Review of studies on lie detection. Overall accuracy rate of 57% (chance = 50%). Vrij (2000): Summary of 39 studies published 1980-2000. Overall, 56% correct. Truth bias – people tend to judge messages as true. Consequently appear better at identifying truthful messages (67%) and worse at identifying lies (44%).
Bond and DePaulo (2006): Meta-analysis of 206 studies involving lying betwen strangers (24,483 deception judgements). Overall, 54% correct at deciding whether statements are truth or lies (poor, but significantly above chance). Truth bias - correctly classify 61% of truths and 47% of lies. More inclined to believe than to doubt messages. Rates of lie detection are consistent across studies.
Bond and DePaulo (2006) (cont.): Poorer discrimination for video-only messages than audio-only or audio-visual. Easier to detect lying from voices than faces. Facial behaviour provides no clues to truthfulness. Motivation to be believed reduces speaker’s perceived honesty (whether or not the speaker is lying). Unmotivated video-only: 54% seen as truthful Motivated video-only : 47% seen as truthful
De Paulo et al (1997), Mann et al (2004): Weak correlation between accuracy and confidence. People tend to be over-confident in their judgements, and more confident when judging a message to be true than judging it to be false. Experts are generally more confident but not more correct.
Bond and DePaulo (2006): A double standard – people judge others’ lies more harshly than their own, and hence think (incorrectly) that behaviour will betray a liar’s stress and guilt. Hartwig and Bond (2011): Wrong subjective cue hypothesis: Stereotypical beliefs about liars’ behaviour do not match how liars actually behave – hence people use invalid cues. Weak objective cue hypothesis: Valid cues to lying exist, but are difficult to detect.
Vrij (2000): (a) Same non-verbal cues can be produced by both liars and truth-tellers (e.g. nervousness). (b) Inadequate scoring systems – not detailed enough (e.g. overall frequency of “grammatical errors” is unrelated to lying, but “repetitions of words or phrases” is; subtle differences between false smiles and real smiles – Ekman 1985). (c) Combinations of cues might be more useful – Micro-facial expressions alone: 80% correct (Frank and Ekman 1997). Micro-facial expressions plus tone of voice: 86% correct (Ekman et al 1991).
O’Sullivan, Frank, Hurley and Tiwana (2009): Claim most studies underestimate lie-detection accuracy, by using (a)undergraduates (b)“low stakes” deception tasks. Claims DePaulo et al’s (2003) study is mainly concerned with detecting trivial lies. Reviewed 23 studies involving police and “high” and “low” stakes lie scenarios. High stakes –67% correct. Low stakes – 55% correct.
Hurst and Oswald (2012): Signal Detection Theory analysis of lie detection: Hits – identify lies. Correct Rejections – identify truths. Misses – think lies are truths. False Alarms - think truths are lies. General public show “truth bias”: more correct rejections at expense of making more misses. Police officers show “lie bias” (Meissner and Kassin 2002, Vrij 2008): more hits at expense of making more false alarms. Hurst and Oswald: Expt 1: Swiss police and UG’s. No lie bias, but police had smaller truth bias than UG’s. Lie bias may occur because police are more worried about Misses than FAs. Expt2: Police only. Manipulating emphasis on consequences of FA’s produced truth bias.
Mann, Vrij and Bull (2004): 99 “ordinary” U.K. police officers. Accuracy for 14 videos of real interviews (independent evidence that the suspect was lying/truthful). Mean accuracy for detecting lies: 66% (chance = 50%). Mean accuracy for detecting truth: 63%. Interview experience significantly correlated with both kinds of accuracy (.18 and.20 respectively). Officers claimed they used gaze and head nods as cues to deceit (police officers are erroneously taught this): the more officers claimed to use such “Inbau cues”, the worse their performance.
Driskell (2012): Meta-analysis of 16 studies on deception training. Considerable variability between studies, but overall, moderate benefits of training. Best results from combination of information, practice and feedback on performance. More effective if emphasised cues of more tension (fidgeting) less sense (less logical, more discrepant) less fluent (word phrase repetitions) Best for inexperienced trainees (fewer preconceptions?) No testing of training’s effectiveness in real-world settings.
Conclusions: People are very poor at detecting lying, because (a) cues are complex and hard to detect. (b) people look for the wrong cues. Experts are no better than general public. Police training programs emphasise wrong cues. Lay people may have truth bias, police have a lie bias. Problems with studying deception: In lab settings, lying is condoned, so no guilt. Low stakes, even in studies with financial rewards for successful lying and penalties for failure (Vrij 2000).