Nonverbal Signs of Lying

Hundreds of studies have examined this issue and the findings are presented below.

For a brief summary see:

Most of the research on the nonverbal signs of lying is driven by the belief that deception is difficult to conceal because...

  • lying takes more mental effort than telling the truth
  • emotions give people away when lying
  • lying causes more stress and anxiety

Essentially, people think that signs of deception should "leak" out through nonverbal behavior, or our body language, which is hard to completely control (see Ekman & Friesen).

So what does the research reveal?

When lying people are more likely to:

  • offer shorter responses
  • make more speech errors—more um’s, er’s ah’s...
  • blink more
  • fidget more

On a side note it should be pointed out that:

  • People do NOT break eye contact when lying

Liars as well as truth-tellers are, on average, just as likely to "look you in the eye."

Unfortunately, all of the research shows that using nonverbal behavior when trying to detect deception is not very useful.

If you doubt that claim, please see what all of the leading experts on the topic have to say (see Science News).

And using technology to detect deception isn’t as useful as people think it is (see ScienceDaily Report).

Why is it so difficult to detect deception by watching a person’s nonverbal behavior?

A detailed explanation is provided below or you can skip ahead to the next page and read why it is even more difficult to detect deception by a loved one (next page, catching lovers lying).

To begin with, there is some truth to the idea that people display or "leak" their genuine feelings when lying. But, these genuine displays of emotion—called "micro expressions"—last only a fraction of a second. As such, these expressions are too brief to be of much practical use (see facial expression test).

Furthermore, the nonverbal cues identified represent "on average" what might happen when studying many individuals rather than identifying what any specific individual is likely to do.

For instance, imagine that you have a group of 1000 men and a group of 1000 women, and you know that, on average, the men are 2 inches taller than the women. Now, say you find out that someone is 5’9". Based on that information alone, can you tell with any certainty, if the individual in question is a man or a woman?

Why not?

The problem with "averages" is that it is difficult to use the information obtained from a large group to make claims back to any specific individual without a lot of other information. After all, there are tall women, short men and everything in-between. So, knowing someone’s height, by itself, does not really help solve the problem of trying to figure out if any given individual is a man or a woman (see Truth, Lies and Romance—provides a detailed example of this type of problem).

Second, the nonverbal cues that have been found are based on small statistical patterns—they are not strong, informative (diagnostic) differences.

This time, pretend that you have a large group of men and a large group of women. But, now the average height difference between the two groups is very small—say less than an half an inch. That half an inch may still be a statistical difference, but because the difference is so small, it is even less useful when trying to guess someone’s sex just by knowing how tall they are.

This is the same problem that occurs when using nonverbal cues to detect deception. The cues represent small, statistical differences between two groups rather information that can be used the other way around; that is, to distinguish liars from truth-tellers.

For example, some studies show that liars blink a few more times on average than truth-tellers (and not every study shows this). Now, say you notice that someone blinks several times while talking to you? Are they telling the truth or not? Who knows? To begin with, both liars and truth-tellers blink when talking (you are probably blinking right now)... And some liars rarely blink while some truth-tellers blink a lot... The graphs below show why the differences obtain are of little use when trying to detect deception...

Differences in Blinking Between Truth-tellers and Liars

graph of differences between liars and truth tellers

In fact, the nonverbal cues that have been identified vary widely from person-to-person, situation-to-situation, and the nature of the lie being told (see Ebesu & Miller; Buller; Burgoon; Buslig & Roiger; Buller, Burgoon, White, and Ebesu; Burgoon, Buller, Ebesu, White and Rockwell).

So, in any given situation anything might happen, and the nonverbal cues that have been found ONLY emerge when looking at group averages.

Long story short, because only small statistical differences in detection cues have been discovered. It is very difficult to identify group members (liars versus truth-tellers) based on the cues that have been identified.

Most people, however, do not believe this claim.

Most people believe that nonverbal behavior can be used to detect deception. But, all the research shows that people no better than "flipping a coin" when trying to detect deception, especially when it comes to love and romance (see Miller & Stiff).

The nonverbal cues that have been identified are not useful because truth-tellers and liars are more similar in their behavior than they are different. And there are many reasons why the nonverbal differences identified are so small and of little practical use (see Fielder & Walka; McCornack).

First, many of the lies that people tell come naturally with no planning, thought, or effort. Lying is often automatic and effortless. Most people are not even aware of the fact that they are lying when they do it. Deception can come across as being "natural" because for many people it is natural.

Second, even if there is some stress or anxiety present when people lie—people typically tell the same lies over and over. Accordingly, people become very comfortable with their lies as time passes. In fact, people tell the same lies so often that they actually begin to believe what they are saying.

Finally, telling the truth can sometimes be just as difficult and stressful than lying. Have you ever been agitated, confused, anxious, or upset while trying to tell the truth only to have people doubt what you are saying? "High stake" situations are stressful for both liars as well as truth-tellers. In such situations, both liars and truth-tellers can get nervous and give off the appearance of telling a lie.

Or think about the problem this way: if detecting deception were so easy, everyone would do it and there would a lot few problems. Affairs, crime, and fraud are only possible because people, even trained professionals, have a difficult time detecting deception with any degree of success. You test your lie detection skills here.

And, for the most part, people are even worse at spotting lies when dealing with someone they love...