Nobody is 100% honest 100% of the time, we’re inclined to believe. In fact, a 2002 study from the University of Massachusetts found that more than half of adults can’t even have a 10-minute conversation without telling at least one lie. You’d think with such frequency that most of us would know how to spot a liar, but it’s more complicated than you might imagine.
That’s why being able to pick up the subtle hints that a partner, friend or family member is telling a lie can be an extremely useful skill to have.
How to tell if someone is lying
According to Kevin O., a New-Jersey based law enforcement officer, there are multiple ways to potentially spot a liar:
Ask an unexpected question. The person may have rehearsed answers to “anticipated” questions.
Listen for complex, formal sentences or excessive talking/repetition. The person may do this to sound legitimate. Overly formal sentences are also a potential sign of a rehearsed story.
Let them talk. While using the right questions to guide the conversation is important, doing most of the talking only requires that they answer your questions. By letting them speak extemporaneously, they may reveal other signs.
Ask them how honest they are. This is a common, surprisingly effective psychological trick used by experts. If you ask, the majority of people will respond that they’re honest people who tell the truth.
Studies have found that starting a conversation in this frame of mind tends to prime people to be more truthful later. And even if they don’t outright admit to lying, claiming to be honest may make it much harder to lie convincingly later on.
Have the person repeat their story backward. Liars tend to memorize and rehearse their story in a certain order. Having to recall the events in reverse order may trip them up.
Look for changes in body language. Too many people falsely believe that there are universal body language cues that indicate lying. Instead, look for changes in an individual’s body language. If they initially appear open and confident but then suddenly meek and withdrawn, you may have reached the false portion of their story.
Make them feel comfortable. To get a feel for someone’s “normal” behavior, Kevin recommended starting out the conversation in a soft, non-confrontational tone to build rapport. Doing so may put the person you’re questioning at ease and make them feel comfortable enough to converse normally.
“The better rapport [you have] with the person you’re questioning, the easier time you will have trying to get the information you need,” added Kevin.
Ask questions you already know the answers to. “This not only helps me gauge their willingness to lie, but I can see if they exhibit any kind of physical sign that accompanies the lie, like a change in stance or body movement,” Kevin said.
Pay attention to who they’re talking about. A gregarious storyteller is more than happy to put themselves at the center of their tales, speaking often in terms of I or me. When lying, however, people tend to focus on anyone else as a way of subconsciously distancing themselves from the lie. If you notice a change in subjects, you may have caught them in a lie.
Again, there’s no single factor that is a guaranteed indicator of a lie. However, observing certain behaviors may cause you to dig deeper and investigate the person’s story further.
Signs of a liar (that actually aren’t)
You might think you know what a liar looks like. “Telltale” signs, such as excessive sweating, fidgeting, darting eyes or tripping over words, are often cited as clear indicators of deception. While these behaviors may very well indicate a particular individual is lying, there simply isn’t one thing that all liars have in common, Kevin said.
“Some people have idiosyncratic ’tells,’ but it’s hard to discover these unless you can catch them in the lie and then associate the signal with lying,” Kevin explained.
“Instead, what we are looking for is signs of abnormal behavior. The more information you have on your suspect’s normal behavior, the easier it will be to pick up on when they are lying.”
People who are exceptionally good liars will typically know that you’re looking for physical signs of a lie and may train themselves to maintain their composure during an interrogation. On the flip side, an innocent person who is telling the truth may have some nervous ticks that could give the false impression of a lie.
Multiple studies have found that attempts to read lies from body language and facial expressions alone are largely incorrect. In one study, just 50 out of 20,000 people could identify a liar from physical cues with over 80% accuracy.
For this reason, polygraph (lie detector) tests cannot be considered accurate or admissible as evidence in court. As John Baesler notes in Smithsonian, polygraph measurements (changes in blood pressure, heart rate, breathing, etc.) are not reliable indicators of deception, because “emotional responses are not uniform among humans and can be imitated by countermeasures.”
What to do when you catch someone lying
So you have concrete evidence that someone is lying to you. Perhaps it’s an incriminating email or text message screenshot, or a timestamped photo that proves the person wasn’t where they claimed to be.
You may want to shove your proof in their face and demand an explanation, but instead of going on the offensive and making accusations, you may want to give them an opportunity to tell their lie.
In a law enforcement setting, suspects are often asked to give their full account of an event, even if the interrogator knows the information is false as they’re telling the story. Kevin explained that when a suspect is telling a story built on a lie, other information in the story is usually impacted by that one false detail.
“I prefer to let the suspect finish what they have to say about the incident in question, then see how far the lie affects everything they have said,” said Kevin.
“Once they’ve stated everything they want to say about the incident on record, you can then go back through their story and pick it apart piece by piece. Every point the suspect has made thus far can now be called into question because their credibility has been lost.”
In other words, listening carefully to the words and details that someone is sharing can help you better spot inconsistencies that are based on that initial lie.
It’s always difficult to think someone you trust isn’t being honest with you. If you believe someone is lying to you, don’t jump to conclusions based solely on signs like fidgeting and eye movement; instead, scan their stance and behavior for anything that jumps out as out of the ordinary.
Remember, if you have evidence that someone is telling a lie, let them tell it—then combat it with the facts you have about the real situation.
“As you pick apart their story, the person understands they have been caught in a lie,” Kevin said. “The truth usually comes out the next time around.”