From The Experts: The Truth About Lie Detection

lie detectors and how the experts feelPolygraph machines, or lie detectors, can be useful tools, but are notoriously unreliable.

We humans might think we have a better shot than a machine at discerning a truth from a lie. But as it turns out, our lie detecting abilities are about the same as a coin flip. As it turns out, much of what we’ve been taught are telltale signs of deception are actually just stress responses, and getting to the truth of a matter is about a lot more than shifty eyes.

Below, we’ve compiled some of the best tips from the foremost experts on human behavior; former FBI agent and founder of the Behavioral Analysis Unit Joe Navarro and psychologist Paul Ekman.

In an article for Forbes, Joe Navarro explains that there isn’t any one behavior, or group of behaviors, that indicate that a person is lying. “The best [I] can do is look for behaviors that shout something is bothering this person when I ask a question. The minute I sense discomfort I wonder why.” According to Navarro, the six key behaviors to look out for are:

  • Lip compression—usually a response to negativity.
  • Ventilating behaviors—a sign of psychological discomfort characterized by an inhale or exhale when answering a question. 
  • Neck touching—a nervous, scared, or anxious response, this can apply to touching the back of one’s neck, the clavicle or neck dimple, or in men, touching their tie.
  • Ventral denial—a coin termed by Navarro himself, this is when someone turns their body away or crosses one leg over the other, as a way for someone to distance themselves from a difficult question. 
  • Eye touching—often a sign of disagreement or intentional deception. 
  • Lowering or hiding thumbs—usually in contrast with an emphatic statement, Navarro reveals that if the thumbs are hidden or pointed down during said statement, this behavior indicates insecurities or lack of commitment on the part of the speaker. Interestingly enough, thumbs pointed up are generally an indicator of truth-telling. 

Psychologist Paul Ekman agrees that “there is no single, definitive sign” that someone is either lying or telling the truth. He believes “deception detection” is a more complex process that is more about establishing an interviewee’s behavioral baseline and then looking for “any deviation from this norm.” As far as body language is concerned, he focuses on three types of gestures:

  • Illustrator gestures, which occur during speech and are used to “illustrate” what the speaker is talking about; 
  • Manipulator gestures wherein one body part “manipulates” another, such as hand-wringing; and
  • Emblem gestures, which have very specific cultural meanings, such as giving a thumbs up, flashing a peace sign, or giving someone “the finger.”

According to Ekman, many people mistakenly believe that a liar will use a lot of manipulator gestures. While he acknowledges that they can be an indicator of discomfort, there could be many factors driving that discomfort, and deceit is not necessarily one of them. However, he does feel that “emblematic slips” are often reliable signs of deception. 

Ekman outlines three common examples of emblematic slips: a “fragment” of a shrug gesture, indicating a bodily contradiction to what is being said; a very small contradictory head shake yes or no; and subconsciously giving the finger while scratching one’s face, or resting a hand on a knee with just that finger extended. 

A good baseline

As far as establishing a good baseline to work from, Navarro offers tips on how to establish psychological comfort for your interviewee. In so doing, you provide yourself with a more reliable baseline from which you can assess answers for deception during four key stages of the interview process. 

While not every interview can take place under ideal conditions, we have pointers here on how best to set up your interview room. Rapport-building, and asking questions with curiosity rather than suspicion, are both ways to create psychological comfort. That way, if a suspect displays nervousness, tension, discomfort, etc., it can be more solidly attributed to the “substance of the question,” rather than how or where it was asked.

According to Navarro, there are four viable opportunities for investigators to detect when a person is hiding something, feels anxious about a question, lies, or has knowledge of guilt:

  1. When being asked a question. Look for restricted body movement, negative affect, or self-soothing—all without being doubtful, suspicious, or intrusive regarding the behavior.

  2. While the interviewee processes the question. Does a subject repeat a question (a potential delay tactic), hesitate before answering, appear to think deeply about the question (a potential sign of cognitive load), or by suddenly locking their ankles around the legs of the chair, staring straight ahead, or darting their eyes as if “looking” for answers?
  3. When answering the question. Does the interviewee give their response with conviction, without hesitation, with an unwavering voice, or with confidence? Do they instead respond passively, in a quiet voice, limit how much space they take up, or pacify themselves?

  4. After responding to a question. Navarro recommends allowing for a purposeful two to four second pause to see how a subject behaves following their answer. Fidgety behavior, long exhales, and self-soothing are all signs of mental stress. 

Although we may wish that lie detection was more a science than an art, the best way we can hone our deception detection skills is through practice. Luckily, with the ability to record interviews, we can not only learn from seasoned investigators, but review the evidence for any clues that might have been missed.