Detection of Deception: Nonverbal Cues

Scientific Study of Nonverbal Behaviors

To find out about potential nonverbal correlates of deception, psychologists and other researchers conduct experiments. They instruct some people to lie and/or tell the truth (the lies are most often “constructed” for the sake of the experiment) and videotape the telling of truths and lies in interviews or mock interrogations. (If the focus is on the speech-related variables, audiotapes are of course sufficient.) Then, these videotapes are closely analyzed, and the frequency and/or duration of a list of nonverbal behaviors are scored. The scored behaviors are then summarized for truths and lies separately, and if statistical comparisons show significant differences, researchers conclude that there are systematic nonverbal signs of deceit and truthfulness. A great number of such studies have been published. In this entry, findings from several meta-analyses and research overviews are summarized.

Included in the concept nonverbal behavior are body movements (e.g., gestures and leg movement), facial indicators (e.g., eye contact, smiling), and speech behaviors (sometimes called paraverbal behaviors; e.g., response latency and pitch of voice).

Theoretical Approaches

Why would the nonverbal behavior of a liar give him or her away? Scientists usually suggest three different [Page 201]processes (or approaches) that might answer that question. According to the emotional approach (sometimes called the affective approach), the three most common types of emotion associated with deception are guilt, fear, and excitement. A liar might feel guilty because he or she is lying, might be afraid of getting caught, or might be excited about the possibility of fooling someone (“duping delight”).

According to the cognitive complexity approach (sometimes called cognitive load or working memory model), the lie should be possible to detect from the liars'nonverbal behavior because it is more difficult to lie than to tell the truth. The liars have to come up with believable answers, avoid contradicting themselves, and tell a lie consistent with what the interviewer knows or might find out. Additionally, they have to remember what they have said, in order to declare the same things again if asked to repeat their statement.

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