'It Can Be Done Very Subtly Or Very Naturally': How To Tell If Someone Is Lying

USA Network’s new reality competition series “Snake In The Grass” will let the viewers in on the action as they, along with each episode's four contestants, seek to uncover the identity of the saboteur among the team. So, ahead of the show’s premiere on Monday, August 1 at 11 p.m. ET/PT on USA Network, it’s worth brushing up on what experts believe are the key ways to tell if someone is lying.

"Snake In The Grass" will see four survivalists dropped off in a remote part of Central America and compete in physical and mental challenges as they survive their conditions for 36 hours. During that time, they’ll have to agree on who the "Snake" is — aka the contestant who's been secretly sabotaging them the whole time. In addition to leaning on their survivalist skills, they'll need intuition and an acute ability to detect lies if they want to walk away with the $100,000 grand prize. 

However, according to body language expert and professional speaker Patti Wood, that’s much easier said than done. Speaking to USA Insider, she explained that it’s one thing to detect a liar in someone’s everyday life — but adding the pressure of a survival situation turns everything up to an 11. 

“What I think is really interesting about this show is that they’re already in a stress-filled situation. So their central nervous system, that limbic response to stress and danger, is already going to be in play,” she said. “That is going to make it more difficult for them to be able to find out who is the saboteur. Because, under normal circumstances, someone who is going to lie, someone who is going to be deceptive, it kicks in your central nervous system, that limbic system response, and you go, ‘Something is wrong, something is wrong, something is not right,’ and it’ll alert you.”

By and large, experts agree that the first step in determining if someone is lying is to establish a baseline. Fidgeting and a lack of eye contact can sometimes be telltale signs that someone is lying. However, if you’re dealing with a person who naturally fidgets a lot or does not make eye contact, suddenly those are less reliable tells. 

As a result, Wood suggests that the most crucial time for the contestants and viewers at home to start making some guesses is when the contestants first meet each other. At this time any lies are low-stakes and people are at their most colloquial. That’s the only behavioral baseline “Snake In The Grass” viewers are really going to get. 

Microexpressions also help. Experts determined that liars very often have flashes of the truth that involuntarily leak out of them. However, these microexpressions usually last for one-fifth to one-25th of a second, so non-experts may miss them completely. A less blink-and-you’ll-miss-it tell is a smile. Forensic psychologist Stephen Porter told NBC News in 2017 that liars tend to smile with their lips closed, a sort of involuntary guard that people not paying close attention may not think much of. However, if one of the four is smirking more often than they are smiling — that could be a big factor in determining if they’re legit or a Snake. 

For those not confident in their ability to read faces, Wood offers some easier advice that involves looking at someone’s demeanor. 

“Think how someone would normally respond to being put in [the wild] and then think, 'How far from normal is somebody?'” she explained. “So to me, one of the clues might be a mismatch. For example, look around and if somebody is ultra-calm and somebody else isn't …”

What's just as important as figuring out the liar is determining who is telling the truth. That’s why experts say to look out for something called “matching and mirroring.” These are involuntary actions like leaning back in a chair, matching another speaker's volume, or participating in spontaneous group activities like applause. People who are telling the truth do them without thinking while people who are actively lying struggle with these natural actions. 

Unfortunately for the truth-tellers on “Snake In The Grass,” spotting the liar is only half the battle. They need to convince everyone else they’ve got the right person. In the trailer, some contestants outright call out their suspect. However, this may not be the best move. 

“The old saying was, ‘Make them scared, call them out,’” Wood explained. “What actually has been shown in the research to be a better technique is to befriend, to try to get them on your side.” 

Unfortunately, Wood noted that’s also the strategy that the Snake would likely go with.

“What they’re probably going to do is make friends with one person and turn them against the others,” she speculated. “It’s something narcissists naturally do, it’s called triangulation. It can be done very subtly, or very naturally.”

Ultimately, experts agree on a handful of ways to determine a liar — establish a baseline, look for deviations, focus on facial expressions and overall demeanor — but there’s no foolproof system. In the end, figuring out a liar is based on how good they are and your own intuition.

The question then becomes: How well will the contestants on “Snake In The Grass” do at figuring each other out in such a high-stress situation?

“Snake In the Grass” premieres Monday, August 1 at 11 p.m. ET/PT on USA Network.