How to Detect When Someone’s Lying (and Get Them to Tell the Truth)

Lies are inevitable, but getting duped isn’t. When you’re in the presence of a liar, you can often uncover the truth by paying attention to very specific nonverbal cues. You just need to ask the right questions and observe their body language to catch them in the act.

What Nonverbal Cues Really Tell Us

You’ve probably heard things like “if someone smirks when they answer a question, they’re lying to you.” You’ve probably even seen shows like Lie to Me, in which characters are able to detect lies through simple body language. However, nonverbal cues are more complicated than popular culture makes them out to be.

When someone’s lying, they will probably give off a few nonverbal cues that suggest something is “off,” but they don’t prove that someone’s lying to you. Joe Navarro, former FBI agent and author of What Every BODY Is Saying, says it best (emphasis mine):

The truth is that there is not one single behavior indicative of deception. [Instead], there are behaviors that are indicative of when a person is having distress, or anxiety, or psychological discomfort.

Lying can cause this type of distress, but so could many other things. For example, Navarro interviewed one woman who showed all of the nonverbal cues one might associate with deception, but in reality she was nervous because her parking meter had run out and was merely afraid of getting a ticket.

Even lie detectors are susceptible to this weakness, so you need more evidence to truly detect a lie.

Use Nonverbal Cues to Investigate Possible Lies

While nonverbal cues won’t prove that someone’s lying, they can direct your investigation by highlighting the important clues. Pamela Meyer, author of the book Liespotting and CEO of deception training company Calibrate, says you should start off an interview by asking your suspect easy, stress-free questions. From there, you can get a “baseline” of their body language when they aren’t under any pressure. Then, when you start asking more pointed questions about the lie you’re investigating, you can pick out which words make them more anxious or distressed.

Navarro gives a great example in this blog post regarding a murder. The medical examiner in this murder determined that the victim was stabbed with an ice pick—a detail not yet known to the public. The investigator used this detail to see if his suspect was as innocent as he claimed:

Rather than ask the subject questions that had previously been covered, such as if he had committed the crime or his whereabouts at the time in question, the investigator asked the following series of questions with a time delay in between: “If you had killed him would you have used a gun?,” “If you had killed him would you have used a knife?,” “If you had killed him would you have used an ice pick?,” and “If you had killed him would you have used a machete?”.

To all of these questions, the subject answered, “No,” however, the nonverbal responses to each question were clearly not all the same. When the ice pick was mentioned, the subject lowered his eyelids and left them low for several seconds before rubbing them with his fingers and answering, “No.” This eye-blocking behavior was enough to convince the investigator that not only did he have the right individual; he also realized the topic to pursue. In the end, after continued questioning about the ice pick, the subject began to reveal what happened the night of the murder. He was betrayed by his own eyes because of his guilty knowledge.

You can still employ this technique even without a specific detail like the ice pick. To use a simple example, say your little brother stole your prized autographed baseball. You could ask him:

-If you had stolen it, would you have hidden it under your bed?
-Would you have hidden it in your sock drawer?
-Would you have hidden it in your closet?

If you get a nonverbal cue that stands out among the others—say he rubs his eyes as in the ice pick example—you have a detail you can investigate further. Again, you can’t accuse him of lying right then and there (after all, he could just have been rubbing an itch), but you do have something that can further your investigation.

Get Liars to Confess When You Have Enough Evidence

So if you can’t make accusations from simple nonverbal cues, how do you finally get to the truth of the matter? In the case of the missing baseball, say your little brother seemed nervous after you asked about his sock drawer. You could simply go and check his sock drawer to see if he had the baseball, giving you clear evidence that he had stolen it and was lying. Other times, Navarro notes, knowing your subject is lying is all that you need. He recalls a story of a friend who wanted to buy a building in Manhattan:

When the seller was asked general questions there were glowing responses about the building. However, when my friend asked about the “last time the duct work had been cleaned” the man ventilated his collar and coughed before he answered (pacifiers). Later he ran his hands through his hair multiple times to the question, “have there been any liens on this property?” My friend hired an investigator, not just a real estate agent, and found there were all sorts of issues with this property. His careful use of nonverbals detected issues which in the end made him wisely terminate further interest in the building. To this date, he still does not know the full truth about the building, he just knows that a lot was being concealed and the investigator confirmed there was enough there to avoid proceeding any further.

Of course, not all cases are so simple. If you really need the detailed truth, you may have to ask quite a few questions before you have enough evidence to figure it out. In other cases, if you ask the right questions, the person will realize you’re onto them and confess. Whatever you do, though, Meyer says putting pressure on them isn’t the answer:

First of all, don’t try to be like the guy on Law and Order pummeling your subject into submission…it doesn’t work. Find a relaxed, quiet, totally private place that’s free of distraction, develop rapport with your subject, let them tell you their story, and then raise the cognitive load on them by asking them to tell it to you backwards. Liars often rehearse their story in chronological order, and law enforcement interrogators in particular often use the technique of asking one to tell the story in reverse order, in order to observe indicators of deceit. We rehearse our words but we rarely rehearse our gestures.

In general, a truthful person will have less of a problem telling their story backwards (though it may still be a tad difficult). Navarro agrees that pressure is a bad strategy, noting that “if you use any kind of pressure on somebody, what you’re going to get is compliance. Compliance gets you a limited amount of information.” Cooperation, on the other hand—building up that rapport and that trust—will have them giving you much more.

In the end, Meyer says, honesty and compassion can go a really long way:

The best way to do this is to signal through your words and actions that your world is an honest one, that you act with integrity. Also why look down your nose at someone who just committed a moral act you never would? What’s the point? Try hard to be focused on facts and not on judgement of others. Often people will feel more freedom to be honest when they do not feel that their questioner is being morally dismissive or superior. As well, try to understand one’s motivation for doing whatever they are lying about, and provide a no-judgements attitude when discussing what motivated them, And never ask “why did you do it?” Asking “why” directly always puts someone on the defensive. Instead suggest several different reasons one might have for committing whatever act is under discussion and let your subject choose what to share with you.

In short: The less accusatory of a tone you take, the more likely you’ll get cooperation from your subject. Know what questions you need to ask, look for the right cues, and do some digging yourself. When you’ve uncovered enough evidence, you’ll either have a strong case for the truth or they’ll confess to you willingly.

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