How to Spot a Liar: 9 Common Signs and What Research Shows

Can you tell when someone is lying to you? Most people believe they can, usually by watching for shifty eyes or nervous fidgeting. Decades of research say otherwise: in a review of more than 200 studies, people spotted lies only about 54% of the time, barely better than a coin toss. The signs that actually help are less about body language and more about the story itself: whether it stays consistent, whether it fits facts you can check, and whether the person has a record of honesty. Below are nine signs that are often repeated, with an honest look at which ones deserve your attention.

Why spotting lies is harder than it looks

Lying is ordinary human behaviour. Most lies are small social ones ("I love the gift"), and the people telling them rarely show any dramatic tell. Psychologists Charles Bond and Bella DePaulo pooled results from studies involving thousands of judges and found an average accuracy of about 54%. Police officers, customs agents and other professionals did not do much better than everyone else.

One reason is that nervousness does not equal guilt. An honest person who senses they are not being believed often becomes anxious, and anxiety looks a lot like the stereotype of a liar. Meanwhile, a practised liar who is calm and prepared may seem perfectly at ease.

So treat each sign below as a reason to ask more questions, never as proof.

Nine signs people look for, and how reliable they are

1. The story keeps changing

If details shift each time you hear an account, such as the time, who was there, or what was said, that deserves attention. Truthful memories also change a little with retelling, so small gaps are normal. What matters is a pattern: key facts that contradict each other, or a version that changes once you mention something you know.

2. They won't meet your eyes

This is the most widely believed sign of lying worldwide, and one of the weakest. Research summarised in The Jury Expert found that truth-tellers look away about as often as liars do. Some studies even find that people who are deliberately lying hold eye contact longer, because they know they are being watched. Culture, shyness, autism and plain discomfort all affect eye contact.

3. They fidget

Restless hands and shifting in a chair are another popular cue with little evidence behind it. Motivated liars often do the opposite: they tend to move less and gesture less, as if trying to control every part of how they come across.

4. They seem tense or anxious

Your sense that "something is off" is worth noticing, but it is not evidence. Anxiety has many causes, including the stress of being questioned. Use the feeling as a cue to look at the facts more closely, not as a verdict.

5. They keep adding details

New details that only appear after you have raised a doubt can be a sign that a story is being patched as it goes. A practical test is to ask the person to tell it again from a different angle, or in a different order. Invented accounts are harder to rebuild on the spot.

6. They seem troubled or withdrawn

Someone who has lied to a person they care about may feel guilty and quiet. But people also go quiet when they are hurt, tired or worried about something else entirely. This sign tells you about mood, not truth.

7. They keep their distance

Stepping back or avoiding someone after a disputed conversation can reflect fear of confrontation, but it also happens when a person feels accused unfairly. On its own, it proves little.

8. The story doesn't fit the facts

This is the strongest sign on the list. If you know something for certain that contradicts what you are told, such as a receipt, a message or a witness, you are no longer reading body language; you have evidence. Researchers find that checking claims against independent facts is far more reliable than judging demeanour.

9. They have lied to you before

A track record matters. An old saying, often attributed to TV psychologist Dr. Phil McGraw but much older in various forms, holds that past behaviour is the best predictor of future behaviour. Repeated, proven dishonesty is a fair reason for caution, though people can and do change.

What actually works better

Research on interviewing points to a few approaches that help more than staring at someone's face:

• Focus on content, not behaviour. Truthful accounts tend to include more specific, checkable details, such as places, times and sensory details. Fabricated ones are often vague and oddly tidy.
• Ask open questions and let the person talk. The longer and freer the account, the more there is to compare with known facts.
• Hold back what you know. Swedish researchers Pär Anders Granhag and Maria Hartwig developed the "strategic use of evidence" technique: you ask for the full story first and only then raise the facts you already have. Liars tend to avoid or contradict that evidence; truth-tellers tend to mention it freely.
• Ask unexpected questions. Lying takes mental effort. Questions a person could not rehearse, or a request to retell events in reverse order, can expose a made-up account.
• Talk it over with someone. One experiment found that small groups judging together did somewhat better than individuals, though the gain was modest.

Myths worth dropping

• "Liars always look up and to the right." Tests of this eye-movement idea have found no link with lying.
• "Professionals can always tell." Experts are only slightly more accurate than ordinary people on average.
• "A polygraph proves it." A 2003 review by the US National Research Council found little basis for expecting polygraph tests to be highly accurate, and innocent people can fail them.

Using this in everyday life

In families, friendships and workplaces, the goal is rarely to "catch" someone. It is usually to understand what happened and decide whom to trust. Ask calm, open questions, check what can be checked, and give weight to a person's long-term track record over a single nervous moment. When trust has broken down repeatedly in a close relationship, talking with a counsellor can help both sides more than any list of tells.

Sources: original list by Derrick Ivey for I Heart Intelligence; Bill Grimes, "Looking for Lying in All the Wrong Places", The Jury Expert, August 2015; Lie detection (Wikipedia).