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Detecting Deception: Verbal Cues More Reliable than Non-Verbal

According to Vrij’s research, focusing primarily on body language as a means to spot deception is less reliable than verbal cues.  In fact, detecting deception via body language creates a higher “lie bias” or what we call “pre-conception” about a person’s credibility.

Practical Kinesic Interview & Interrogation® focuses predominantly on verbal behaviors for credibility assessment and uses body language cues to evaluate emotional response behaviors and to spot “contradiction” signals between voice and body.  Body language cues appear to have a very high error rate in credibility assessment.

…deception research has revealed that many verbal cues are more diagnostic cues to deceit than nonverbal cues. Paying attention to nonverbal cues results in being less accurate in truth/lie discrimination, particularly when only visual nonverbal cues are taken into account. Also, paying attention to visual nonverbal cues leads to a stronger lie bias (i.e., indicating that someone is lying). The author recommends a change in police practice and argues that for lie detection purposes it may be better to listen carefully to what suspects say.

Previous research has shown that suspects in real-life interviews do not display stereotypical signs of nervous behaviours, even though they may be experiencing high detection anxiety. We hypothesised that these suspects may have experienced cognitive load when lying and that this cognitive load reduced their tonic arousal, which suppressed signs of nervousness. We conducted two experiments to test this hypothesis. Tonic electrodermal arousal and blink rate were examined during task-induced (Experiment 1) and deception-induced cognitive load (Experiment 2). Both increased cognitive difficulty and deception resulted in decreased tonic arousal and blinking. This demonstrated for the first time that when lying results in heightened levels of cognitive load, signs of nervousness are decreased. We discuss implications for detecting deception and more wide-ranging phenomena related to emotional behaviour.

Stan B. Walters, CSP “The Lie Guy®”
Practical Kinesic Interview & Interrogation®

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