Most people lie, whether they're covering up something sinister or just embarrassed over a mistake. Research conducted a few years ago at the University of Massachusetts found that 60 percent of participants lied at least once during an observed 10-minute conversation.
If you're trying to get to the bottom of a work incident, or just asking the kids who broke the TV, it's useful to know how to spot a lie (Learn interview and interrogation techniques in How to Spot a Liar).
Body language expert and human behavior specialist Carolyn Finch, who served as a consultant and analyst for media outlets during the OJ Simpson trial, has appeared on CNBC News and the Ellen Degeneres Show. Here Finch gives a rundown of the hallmark physical signs people display when they are trying to put one over on you (Watch the video for Carolyn's analysis and her recall of famous cases of alleged lying).
Obviously these signs don't guarantee that lying is in progress, but they're valuable clues to recognize.
Tense facial expression
When people lie, said Finch, they tend to smile with only the lower muscles in their face. A liar might try and fake a smile to look genuine or at ease. But a real smile uses the entire face, including the eyes.
"You will see smiling that is artificial," said Finch. "It's down here (the lower face) instead of in the eyes."
Hesitant speech and pausing
A liar will speak hesitantly, according to Finch, and often pauses frequently when answering a question. A liar might also repeat words or stutter, she said.
"A person who is pausing is thinking," said Finch. "The eyes go up and around and down to think about what they are going to say next."
A liar might also place a finger in front of their mouth, as if contemplating, when they are about to say something that is untrue.
"When they open the mouth, they may give you whole different story than what they might have said when they were thinking with the finger over their mouth."
Nervous behavior and overemphasis
Other face touches might include nose rubbing or touching underneath the nose, all indicators the person is uncomfortable. And watch hands closely, which are an easy way to spot nervousness.
"Sometimes there is tremor, definitely in the hands," said Finch, who also noted the jaw might shake, too.
"The jaw is usually level with floor when a person is talking to another person. But (when lying) the jaw is going to go down, there can be a tremor, it's tight, like: 'Yes you better believe me,' and they're overemphasizing it."
Finch said Bill Clinton's now famous statement in 1998 about his relationship with Monica Lewinsky is an example of this kind of overemphasis. Clinton, who later admitted to an inappropriate relationship with the White House intern, initially told the public: "I did not have sexual relations with that woman; Ms. Lewsinky."
"This [Clinton's hand gestures] is making a very sarcastic point," said Finch. "(He's saying) 'Do you hear me? Do you hear me?' It's almost a sarcastic, sharp point saying: 'OK, what's matter with you people?' This was accompanied with a lot blinking, much more than ordinarily seen with Bill Clinton."
Lack of eye contact or shifty eyes
Liars will sometimes avoid making eye contact, but these days many know that eye contact has become a well-known indicator. It is therefore not as good of a sign as it used to be, said Finch, because liars will make a concerted effort to keep your gaze so as not to arouse suspicion. However, Finch advises studying where there eyes go if, and when, they do break gaze.
Finch said she immediately recognized that Susan Smith, who was convicted of drowning her two children in 1994, was lying during a TV interview. Before Smith was charged with the crime, she told police and the media that her children were abducted and that she didn't know where they were.
"With Susan Smith, I looked at her eyes and knew. Her eyes were up to her left. She was visualizing what had happened. Then she was down to the right. That's when I knew she knew exactly where her children were."