Detecting Deception: Key Indicators

Number One: Excessive Gestures

According to a 2015 study presented at the International Conference on Multimodal Interaction, liars move their hands more than truth-tellers. This study is one of the most compelling pieces of research on deception. It uses data from real-life court cases to assemble a list of common deceptive tells and cues. It turns out excessive gesturing is near the top of the list. When people lied in these court cases, they moved their hands much more than people who were telling the truth.

But what do gestures have to do with deception? Hand gestures help people to release nervous energy. Deception places significant mental stress on the brain, so liars need a physical outlet for their stress. Some shake their legs, others tap their fingers, but in this study, liars were releasing nervous energy by waving their hands.

But that's not the only reason people gesture when they lie. Hand gestures are commonly used by public speakers to enhance their arguments. Calculated gestures make them more convincing. A well-timed hand gesture can strengthen a point, spark a question, or inspire an audience. In the same way, a liar may use hand gestures to convince someone their story is true. As both an outlet and a tool, excess hand gestures are one of the most significant signs of deception. If you see someone who can't stop waving their hands around, be careful. They may be lying to you.

Number Two: Deceptive Scowls

A liar may cover their tracks with a bulletproof story, but sometimes you can read a lie on someone's face. In the same 2015 study, researchers found differences in the facial expressions of liars and truth-tellers. It turns out liars are more likely to express negative emotions on their face.

Just imagine asking someone a question like, "Have you ever cheated on a test?" Their answer is important, but their physical reaction is even more telling. Truth-tellers will usually express surprise or confusion when asked a difficult question. Liars, on the other hand, unconsciously scowl or frown. They know they have to lie, and that lie creates stress on their face. Their facial expression gives them away no matter how good their story is.

Number Three: Keeping Eyes Open

Many people think liars avoid eye contact, so they're fooled by people who maintain steady eye contact throughout the conversation. The truth is good liars have no trouble looking into people's eyes. Our study of real-life court cases found that liars keep their eyes wide open while they talk. Good liars also look directly at the person asking them questions. In other words, minimal eye contact is not a reliable sign of deception, but excessive eye contact is.

When a good liar wants to deceive someone, they maintain steady and confident eye contact. But researchers found that eye contact during a lie is often unnatural and excessive. For example, liars will stare too long and avoid closing their eyes. Truth-tellers, on the other hand, are much more flexible with their gaze. They'll make eye contact, break eye contact, close their eyes, and open their eyes. Liars have to think about how people perceive their gaze, but truth-tellers don't need to. And as strange as it sounds, good eye contact can be deceiving.

Number Four: Autonomic Distress

Lying places emotional stress on your body and brain. This stress triggers physical reactions which show themselves in small but telling ways. Lying primarily affects the autonomic nervous system. Your autonomic nervous system controls a number of unconscious processes like heart rate, breathing rate, and digestion. Because lying stimulates a reaction, deception is associated with escalated heart and breathing rates. The stress of lying unconsciously impacts the function of your body.

Now, of course, you can't see someone's heart rate with your own eyes, so how do you know if someone is lying directly to you? The autonomic nervous system also affects surface-level functions like blinking, coughing, sweating, and swallowing, which are all common signals of distress in the autonomic nervous system. So if someone has nothing to hide, their nervous system should behave normally, but if they're lying, their nervous system will go haywire. You may notice them blinking far more than they need to or swallowing every few seconds. Either way, their nervous system is trying to tell you something: they're not telling the truth.

Number Five: Distant Pronouns

Liars tell stories differently than truth-tellers. The next time you're listening to a suspicious story, pay attention to the pronouns. First and second-person pronouns like "I," "me," and "you" show a personal attachment to a story. Truth-tellers have no problem using these pronouns because they're telling the truth. They have nothing to hide, but liars subconsciously change the pronouns they use.

Why? Because third-person pronouns like "he," "she," and "they" create distance between the story and the storyteller. Deep down, liars avoid taking credit for their lies. They know they're not telling the truth, so they use pronouns to create mental space. It can be difficult to spot, but this tiny act of deception can reveal when someone's lying to you.

Number Six: Jumps in Volume

When someone is lying, their emotions influence the way they communicate. All right, let's say you're having a normal conversation with your friend. You're talking comfortably back and forth when suddenly their voice changes. It gets loud and harsh, and out of nowhere, it feels like they're scolding or yelling at you.

Vocal changes are commonly associated with deception. When you lie, you get defensive and flustered. You lose control of your voice, which increases your volume and changes your tone. And when you think someone's lying, just pay attention to any changes in their voice. If they suddenly get louder and angrier, this person may be deceiving you.

Number Seven: Telling the Truth

Now, this may be the most obvious signal on this list, yet so many people overlook what's right in front of them. Let me ask you a question: What's the best way to get someone to think you're telling the truth? How about literally telling them that you're being honest?

Many liars, especially those who don't lie often, use phrases like "to be honest" or "to tell the truth" when they're about to lie. If someone was telling the truth, they wouldn't need to remind you. If someone is an honest person, they wouldn't tell you that they're being honest. So keep an eye out for these tell-tale phrases. If you hear someone emphasizing their honesty, well, they may be trying to trick you.

Number Eight: Recycled Phrases

Liars have a hard time expanding on their stories. If you think someone is lying, try asking the same question in three different ways. You may notice them using the same scripted phrases over and over. These phrases are designed to protect them, but any good interrogator knows recycled phrases are a dead giveaway.

If someone was telling the truth, they could explain one story from several different angles. They could mix up their phrasing without jumbling the facts, but liars rarely can. They stick to the same phrases because they're worried about their story. So watch out for these recycled phrases. If someone repeats the same language, well, they may be trying to deceive you.

Number Nine: Major Mistakes

Sometimes people just make mistakes. You misremember names, you forget how things happened, but there's a huge difference between a small slip and a big lie. All right, let's say you ask your friend what they did last night. They tell you that they stayed home and watched a movie. You asked them what movie they watched, and they get the name wrong. Are they lying or did they just make a mistake?

These slip-ups are not only common, they're almost always harmless. But what if this happened instead? You ask your friend what they did last night, and again they say they stayed home and watched a movie. You asked what the name of the movie was, and they say actually I went out to dinner last night. This is a major mistake. If someone changes a big part of their story, you should be suspicious. It's easy to get a name wrong, but few people misremember an entire afternoon.

Number Ten: The Slippery Slope

People who lie once often lie again because lying is a slippery slope. The more you do it, the easier it gets, and the more likely you are to do it again. This discovery comes from a 2016 study in the journal Nature Neuroscience. Researchers explain that the human brain becomes accustomed to lying. Once your brain profits from a lie, it becomes more comfortable bending the truth. Your stress response decreases, your nervous system becomes less sensitive, and your behavior becomes more controlled.

That's why experienced liars are so difficult to unravel. Honest people usually panic when they lie. Their lies are written all over their faces, but experienced liars are physically and mentally prepared to deceive. So it may be almost impossible to tell fact from fiction.

If you're suspicious of someone, take their past into consideration. Do you trust this person? Have they lied to you before? If they're honest, give them the benefit of the doubt. You'd probably know immediately if they were lying. Now, on the other hand, if this person lies often, stay on your guard. No matter how convincing their story sounds, there's still a chance they're bending the truth.

Understanding the Signs

Sign	Description	Example
Excessive Gestures	Liars move their hands more than truth-tellers	Frequent hand-waving
Deceptive Scowls	Negative facial expressions are more common in liars	Scowling or frowning when lying
Keeping Eyes Open	Liars maintain steady, unnatural eye contact	Wide, unblinking eyes
Autonomic Distress	Lying causes physical stress reactions	Increased blinking, coughing, or sweating
Distant Pronouns	Liars use third-person pronouns to distance themselves	Using "he" or "she" instead of "I"

Further Reading

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