You would expect the best way to identify a liar is by looking them in the eyes.

Yet a research study from the University of Michigan indicates that people who lie look their questioners in the eyes more often than people telling the truth.

The researchers studied 118 video clips to determine the language and gestures used by people who are being dishonest. They looked at video clips from case trials and used data from the Innocence Project which handles legal cases of innocent people who have been falsely imprisoned.

They concluded what differentiates people who lie from those telling the truth: people who lie move often have animated hand gestures.

That’s right. If you want to identify a liar, look at their hands.

People are good lie detectors – if we know what to look for

“People are poor lie detectors,” said Rada Mihalcea, professor of computer science and engineering who leads the project. “This isn’t the kind of task we’re naturally good at. There are clues that humans give naturally when they are being deceptive, but we’re not paying close enough attention to pick them up. We’re not counting how many times a person says ‘I’ or looks up. We’re focusing on a higher level of communication.”

The researchers identified who to look for in liars, finding the following common behaviors:

  • Scowling or grimacing of the whole face. This was in 30 percent of lying videos vs. 10 percent of truthful ones.
  • Looking directly at the questioner—in 70 percent of deceptive clips vs. 60 percent of truthful.
  • Gesturing with both hands—in 40 percent of lying clips, compared with 25 percent of the truthful.
  • Speaking with more vocal fill such as “um.” This was more common during deception.
  • Distancing themselves from the action with words such as “he” or “she,” rather than “I” or “we,” and using phrases that reflected certainty.

The researchers presented their findings at the International Conference on Multimodal Interaction and believe their work may be useful for security agents and juries.

Of course, it’s far from foolproof. It’s difficult to use these findings to definitively determine whether someone is telling a lie or not. Rather, the findings can be used to generalize across a group in the population.

The reality is that everyone behaves slightly differently when telling a lie. The research results are useful as a guide for someone wanting to know whether someone is telling the truth.

The next time you’re in a situation when you want to know if someone is telling the truth, look at their hands. But don’t rely on these findings in finding the people telling lies in your life.