How to Tell if Someone Is Lying

Can you tell when someone is lying to you? While we might like to think that we are good at catching lies, the evidence tells a different story. In fact, much of the research says that spotting a lie hinges more on how bad the liar is at telling it rather than how good the other person is at spotting it.

Some types of lying (like telling someone you like their outfit or love their new haircut) can be an important social skill. They help us maintain harmony and foster more positive interpersonal relationships. Other lies can be much more destructive and take a serious toll on mental health and well-being.

Keep reading to learn more about some of the tactics that might help you tell when someone is lying, and why lying is often so hard to recognize.

Verywell / Brianna Gilmartin

How Often Do People Lie?

Lying and deception are common human behaviors, but until recently, little research has been done into how often people lie and how often they can detect this type of deception.

Research suggests that about half of all lies were told by just 5% of all the subjects. The study suggests that, although prevalence rates vary, a small group of prolific liars likely exists.1

The reality is that most people probably lie from time to time. Some of these lies are "little white lies" intended to protect someone else’s feelings (“No, that shirt does not make you look bad!”). In other cases, these lies can be much more serious (like lying on a resume) or even sinister (covering up a crime).​

In reality, everyone lies from time to time. However, a small group of people tell the vast majority of lies and many of them tend to be very good at it—which is what can make it so difficult to tell when someone is lying to you.

Signs Someone *Might* Be Lying

Unfortunately, there's rarely a sure-fire sign to reveal that someone is lying. However, there are a few potential red flags that might indicate that someone is lying, including:

• Being vague and offering few details


• Repeating questions before answering them


• Repeating the same story over and over


• Speaking in sentence fragments


• Explaining things in strict chronological order


• Sounding like they are repeating a rehearsed script


• Failing to provide specific details when a story is challenged


• Failing to give a straightforward response to a simple yes or no question


• Grooming behaviors such as playing with hair or pressing fingers to lips


• Physical changes that indicate a fight-or-flight response, like increased sweating, muscle tension, restlessness, and fidgeting

How Can You Tell When Someone Is Lying?

If you suspect that someone might not be telling the truth, look at these indicators to help distinguish fact from fiction:

Body Language

When it comes to detecting lies, people often focus on body language "tells," or subtle physical and behavioral signs that reveal deception. For example, shrugging, lack of expression, a bored posture, and grooming behaviors such as playing with hair or pressing fingers to lips can give away a person who might be lying.

However, although such body language cues can sometimes hint at deception, research suggests that many typical "suspect" behaviors are not always associated with lying.2

Howard Ehrlichman, a psychologist who has been studying eye movements since the 1970s, has found that they don't signify lying at all. In fact, he suggests that shifting eyes means that a person is thinking, or more precisely, that they are accessing their long-term memory.3 More recent research also suggests that eye movements are associated with cognitive activity.4

Similarly, other studies have shown that, although individual signals and behaviors are useful indicators of deception, some of those most often linked to lying (such as eye movements) are among the worst predictors.5

The lesson here is that, although body language may be helpful, it is important to pay attention to all the possible signals.

One meta-analysis found that, although people often rely on valid cues for detecting lies, the problem might lie with the weakness of these cues as deception indicators in the first place.6

Vocal Cues

Uncertain speech can indicate discomfort and a guilty conscience. If the person seems unsure or insecure, they are likelier to be perceived as lying.

One study found that liars are less likely to produce cues that people associate with lying, possibly because they consider the listener's expectations and modify their behavior accordingly to reduce the likelihood of being caught.7

Some research suggests that verbal cues are a promising way to distinguish between truth and lies. In such cases, these cues rely more on the content of what the person is saying than on things like tone of voice.8

Language Cues

Look for someone who is telling a lie to leave out important details. After all, they can't be called out for lying about a minor element of a story (and therefore the entire fabrication) if they don't relate it in the first place.

Researchers have come up with a strategy to ferret out lies using the concept of cognitive load. In a study of people asked to report stories in reverse rather than chronological order, the additional challenge made other verbal and nonverbal cues more apparent.9

Lying is more mentally taxing than telling the truth. If you add even more cognitive complexity, behavioral cues may become more apparent.

Not only is telling a lie more cognitively demanding but liars typically exert considerable mental energy on monitoring their behaviors and evaluating responses to maintain credibility. Lying is, frankly, mentally exhausting.

It often requires pursuing a goal, using working memory to maintain the lie, using psychological flexibility to adjust to changes in context, and using attention to monitor the situation. Adding to the mental load makes lying much more difficult and cognitively taxing.10

Some experts suggest that relying too heavily on certain signals may impair the ability to detect lies.11

Instinctual Cues

Above all, listen to your gut reactions. Researchers had 72 participants watch videos of interviews with mock crime suspects. Some had stolen a $100 bill off a bookshelf; others had not. All suspects were told to say they had not taken the money. Interviewers could not consistently detect lies, accurately identifying the liars only 43% of the time and the truth-tellers 48% of the time.12

Researchers used implicit behavioral reaction time tests to assess the participants' more automatic and unconscious responses to the suspects. The subjects were more likely to unconsciously associate words like "dishonest" and "deceitful" with the suspects who were actually lying.12 They were also more likely to implicitly associate words like "valid" and "honest" with the truth-tellers.

The results suggest that people may have an unconscious, intuitive idea about whether someone is lying.

How to Understand and Cope with Compulsive Liars

Why Lying Is Hard to Detect

Conscious responses might interfere with our automatic associations. Instead of relying on instinct, people focus on stereotypical behaviors associated with lying, such as fidgeting and lack of eye contact. However, an overemphasis on such unreliable indicators makes distinguishing between truth and lies difficult.13

People Are Not Good at Spotting Lies

People are surprisingly bad at detecting lies. One study, for example, found that people were only able to accurately detect lying 54% of the time in a lab setting—hardly impressive when factoring in a 50% detection rate by pure chance alone.6

One study found that training people to detect lies increased performance to approximately 70%. This suggests that people can become better at spotting lies—but it's hardly a perfect process, and they make plenty of mistakes.14

Other researchers criticized these findings based on methodological problems. Subsequent analysis suggests that training yields a much less significant advantage.15

The reality is that there is no universal, surefire sign that someone is lying. All of the signs, behaviors, and indicators that researchers have linked to lying are simply clues that might reveal whether a person is being forthright.

Takeaways

Next time you are trying to gauge the veracity of an individual's story, stop looking at the clichéd "lying signs" and learn how to spot more subtle behaviors that might be linked to deception. When necessary, take a more active approach by adding pressure and make telling the lie more mentally taxing by asking the speaker to relate the story in reverse order.

Finally, and perhaps most importantly, trust your instincts. You might have a great intuitive sense of honesty versus dishonesty. Learn to heed those gut feelings.