28. How to Spot a Liar (Hint: Stop Staring at Their Eyes)

This post was inspired by The Diary of a CEO episode with Dr. Leanne ten Brinke, a psychologist who runs the Truth and Trust Lab at the University of British Columbia.

A World Full of Fakes

The world is full of lies and deception, and as we move further into the future, we're facing a plethora of AI deepfake videos and images that make our brows furrow in suspicion.

Nobody would mistake that new AI video of Jensen Huang for the real thing.

In October 2025, a fake, AI-generated Jensen Huang went live on YouTube at the exact same time as the real Nvidia keynote, promising viewers they'd get back more crypto than they sent in. At one point, nearly 100,000 people were watching, about eight times as many as the real stream. Videos like these are warning signs that the line between real and fake is starting to blur.

So much of what surrounds us, from the ad screens in our apartment elevators to the ads on YouTube and TV, is a quick cash grab that dazzles us and plays on our biases.

But what really stings is when someone we love and trust lies to us. And to rub salt in the wound, it feels even worse when we realize we've been fooled for a long time. So here are some tips on how to spot liars, backed by research from psychology labs around the world.

Why Staring at Their Eyes Doesn't Work

Traditionally, we've tried to spot liars by watching their eyes. Do they look away? Or do they glare at us a little too hard? We've also watched their hands, their fidgeting, and their body language. But according to Dr. Leanne ten Brinke, these are mostly unreliable cues.

Ask people around the world for the number one sign of lying, and most will say the same thing: liars can't look you in the eye. Yet when researchers combined the results of many studies, they found no evidence that adults look away more when they lie.

Think about it for a second. Everybody knows the "liars can't look you in the eye" rule, including liars. Eye contact is easy to control, so a liar who wants to be believed will simply lock eyes with you. In one study at an airport, liars actually made more deliberate eye contact than truth-tellers. They were overcorrecting!

The eye rule can also be unfair. Many autistic people find eye contact uncomfortable, and in studies, autistic adults telling the complete truth were more likely to be judged as liars. Culture matters too. In Korea, many of us grew up learning that staring straight at an adult who is scolding you looks rude. Looking down in that moment is a sign of respect, not guilt.

Reality Check: You're Basically a Coin Flip

So how well do these old tricks work? Not well at all.

In 2006, researchers Charles Bond and Bella DePaulo combined the results of more than 200 research papers in which about 24,000 people tried to tell liars from truth-tellers. The average accuracy was 54%. Flipping a coin gets you 50%. In other words, the average human lie detector is only a sliver better than a coin.

Dr. ten Brinke has tested this in her own lab, and her setup sounds like a heist movie. Volunteers had the chance to steal a $100 bill from a room. Then everyone, thieves and innocent people alike, had to deny it in an interview. If a thief convinced the interviewer, they got to keep the money! When other people later watched those interviews and guessed who the thieves were, they weren't very good at it.

It gets weirder. In the big 2006 analysis, people correctly identified about 61% of truths but only 47% of lies. Psychologists call this the truth bias: our brains lean toward "believe" by default. That isn't because we're gullible. Most people tell the truth most of the time, so believing them is usually a smart bet. The trouble is the rare moment when it isn't.

The Real Tell: Liars Run Out of Details

According to Dr. ten Brinke, the best way to spot a liar is to focus on the content of their words, not the movements of their face. Here's why. Liars have to spin up the details of a scenario that never happened. So when you ask the right follow-up questions, they have to burn far more mental energy to keep their fake story standing.

Psychologists call this cognitive load. Picture two people answering the question, "What did you do last Saturday?"

The truth-teller just presses play on a memory. The details are already stored in there.

The liar is juggling at least four balls at once:

1. Inventing new details on the spot

2. Making sure those details don't contradict each other

3. Remembering every detail so they can tell the exact same story next time

4. Guessing what you already know, so they don't contradict something you saw with your own eyes

That's a lot of juggling, and scientists can actually measure it. A review of 114 experiments found that people are consistently slower to give a lying answer than a truthful one. Lying literally takes time.

3 Red Flags That Actually Mean Something

Instead of reading faces, Dr. ten Brinke suggests listening for three signs.

Red Flag #1: Thin or fuzzy details

The most consistent difference researchers find between liars and truth-tellers is the amount of detail. Liars tend to give fewer details. Many people expect the opposite (don't liars ramble on and on?), but the research says no, especially when the liar had no time to prepare.

Watch for a story with a hole in the middle: lots of detail about the boring, true parts, then almost nothing about the part that matters. Researchers call this an embedded lie. For example:

The bananas get eight words. The homework, the only part Mom actually cares about, gets three.

Also listen for slippery, wishy-washy words like "kind of," "sort of," "I guess," or "it wasn't really..." Dr. ten Brinke studied real people who went on TV begging the public to help find a missing family member. Some of them were later found to be responsible for the disappearance. The liars used more of these tentative words, and when her team checked again with a new set of videos years later, the finding still held.

Red Flag #2: Details nobody can check

Ask yourself one simple question: Could I check this? Truth-tellers tend to give details that can be confirmed, like a name, a place, a receipt, a photo, or a friend who was there. Liars lean on details that can't be confirmed. ("I was with a new kid. You don't know him.") Research suggests that focusing on this one question works better than trying to track a dozen body-language clues at once.

Red Flag #3: Visible brain strain

Remember the juggling? Sometimes you can see it happening. The person slows down, says "um" and "uh" a lot, furrows their brow, or takes a long pause before answering an easy question. Be careful with this one, though. People also pause because they're nervous, shy, tired, or just trying to remember what they had for lunch.

The Magic Question: "Tell Me More"

Here's the most surprising part. Training people to stare harder at liars only helps a little. What helps more is learning to ask better questions.

1. Ask open questions, not yes-or-no questions. "Did you do your homework?" gets "Yes." End of story. "Walk me through how you solved number 4" forces a real answer.

   
   

2. When a story feels thin, say four simple words: "Tell me more about that." A truth-teller can keep going because they were really there. They remember the annoying little stuff, like the pencil that kept breaking. A liar has to invent every new detail on the spot, and eventually the juggling falls apart.

   
   

3. Ask something they didn't prepare for. A liar may rehearse the main story, but probably not "What was the hardest part?" or "What did your friend say when you got there?"

Here's how it might sound in real life:

Teacher: How did you solve number 4?

Student A: Ugh, number 4. I divided first and got a weird decimal, then realized I had to find the area first. Took me forever. My pencil broke halfway through, too.

Student B: I just... did it the normal way. It was kind of easy, I guess.

Teacher: Tell me more.

Student A: Okay, so the length was 12 and the width was...

Student B: Um... I don't really remember. It was a while ago.

Student B just waved all three red flags: thin details, a wishy-washy "kind of... I guess," and visible brain strain. Student A might still have the wrong answer, but they're clearly telling the truth about doing the work.

Before You Turn Into a Human Lie Detector...

A few warnings before you start interrogating your little brother.

There is no Pinocchio's nose. None of these signs proves that someone is lying. A thin story might just mean someone is tired or not great at telling stories. And a liar who had time to prepare can stuff their story with fake details. So treat a red flag as a reason to ask another question, not as a reason to accuse someone.

You don't have to judge alone. In experiments, people who talked it over in groups were better at catching lies than people judging by themselves. If something feels off, talk it through with a parent, a teacher, or a friend you trust.

The Plot Twist: Lies Make Us Lonely

Here's the finding that surprised me most. Dr. ten Brinke's lab paired up strangers to chat, and in some pairs, one person was secretly told to lie about everything. The other person had no idea. At the end, the pairs with a liar felt less close than the pairs where both people told the truth. Her team also found that people who lie more in everyday life tend to feel lonelier.

Why? A good conversation is a trade. I share something real, you share something real, and slowly we get to know each other. A liar gives away less of themselves, so the other person walks away feeling like they never really met them, even without suspecting a thing.

Dr. ten Brinke points out that most of our everyday lies are "nice" lies, told to protect someone's feelings. Yet even those seem to build a little wall between people. So maybe the biggest lesson isn't how to catch a liar. It's that the truth is what actually brings us closer.

HOMEWORK

Comment Challenge: Two Truths and a Lie (choose only one below)

Option 1: In the comments section below, write three short sentences about yourself. Two are true, and one is a lie. Then read your classmates' comments and guess their lies using what you learned. Which sentence has thin details? Which one can't be checked? Which one sounds kind of... wishy-washy?

Option 2: In a paragraph length, describe a real time you caught someone lying. It can be something small, like a sibling who "didn't touch" your snack or a friend who "totally finished" the homework. Can't think of one? You can write about a time someone caught YOU lying instead!

Keep it school-safe: no addresses, phone numbers, or anything private.

Sources

• The Diary of a CEO, episode with Dr. Leanne ten Brinke.

• Bond, C. F., & DePaulo, B. M. (2006). Accuracy of deception judgments. Personality and Social Psychology Review.

• Sporer, S. L., & Schwandt, B. (2007). Moderators of nonverbal indicators of deception. Psychology, Public Policy, and Law.

• Mann, S., et al. (2012). Windows to the soul? Deliberate eye contact as a cue to deceit. Journal of Nonverbal Behavior.

• Lim, A., Young, R., & Brewer, N. (2021). Autistic adults may be erroneously perceived as deceptive and lacking credibility. Journal of Autism and Developmental Disorders.

• ten Brinke, L., Stimson, D., & Carney, D. R. (2014). Some evidence for unconscious lie detection. Psychological Science.

• Suchotzki, K., et al. (2017). Lying takes time: A meta-analysis on reaction time measures of deception. Psychological Bulletin.

• ten Brinke, L., & Porter, S. (2012). Cry me a river: Identifying the behavioral consequences of extremely high-stakes interpersonal deception. Law and Human Behavior. Retested in ten Brinke et al. (2025), Law and Human Behavior.

• Verschuere, B., Bogaard, G., & Meijer, E. (2020). Discriminating deceptive from truthful statements using the verifiability approach: A meta-analysis. Applied Cognitive Psychology.

• Hauch, V., et al. (2016). Does training improve the detection of deception? A meta-analysis. Communication Research.

• Klein, N., & Epley, N. (2015). Group discussion improves lie detection. Proceedings of the National Academy of Sciences.

• Crider, M. (2025, October 29). A deepfake video of Nvidia's CEO sent thousands of viewers to a crypto scam. PCWorld.