A human lie detector

Can you use body language to tell if someone is lying?


Mr Michael Cobb

2021-03-16 3 min read

Can you learn to use body language to spot a lie? If you are in the business of interviewing people it is probably something that you have tried to explore before. I’ll be honest with you up front, you probably can’t. Not by itself.

There are a lot of myths surrounding body-language and what it can tell you. The one about it being able to spot a lie is one of the biggest. Whatever many sites may like to tell you, reading body language will not make you a human lie detector. If not, why not?

First let’s talk body language, or non-verbal communication. There is a reason Zoom meetings have taken over from conference calls during lockdown. Over 70% of what we mean and feel during a conversation is expressed using body language. The unconscious raise of an eyebrow or smile says a lot about what your colleague thinks of your dazzling idea and gives you the cue to plough on or stop and reconsider.

We read body language all day, every day and we’re good at it. Except when someone is lying, where we tend to fail, badly. We might get hints or feelings but on the whole we just don’t spot any signs. The reason is quite simple, it’s because most of the signs we are told are signs of lying are pretty common and we’re used to seeing them. No one body language 'cue' is only related to lying. Why then do we still look for the cues?

In part it's because the internet is full of blog posts and articles claiming their 'scientifically proven' signs can somehow be used to tell if someone is lying. The problem is, the fact that a scientist has seen some visual ticks while someone is lying, doesn't meant they are a sign someone is lying. So let us look at the most common myths.

 Looking away:

Here we see the belief that with a look to the right, or up, or is it left, we know someone is lying. The fact that no-one can ever remember which way it is shows just how useless that it is in everyday life. The same goes for the belief that looking away suddenly while talking means someone is lying.

The logic here is that people will literally try and evade the looks of people when they are lying, trying not to get caught. In a 2015 study however the University of Michigan found while some people did look away when they were lying, 70% of those the survey watched actually stared at the questioner. In reality the liar actually tries to brave it out and challenge the listener to call them out.

There is another problem with the theory. It is culturally dependent. Some cultures actually believe that looking someone in the eye is aggressive and will look away. So unless you are a cultural expert, using this method to spot a liar is fraught with all sorts of dangers. And doesn’t work.

Talking more slowly:

The theory behind this one is that the liar slows down their speech to give them time to think through the next stage of a lie. While this looks good in films, the truth is not so dramatic. Lies tend to be spontaneous or rehearsed. In both cases the speech pattern ends up being rushed, respectively leaping at an answer or reciting a pre-planned one. If you are conducting an interview it is also likely that the subject is trying to sound at their best. Universally a slow cadence to our speech is seen as intellectual and wise. Not every teacher was lying to you at school.

Even when a subject starts to increase their pace of speech this doesn’t automatically indicate a shift from truth to lie. When talking about a subject we find interesting, or when we are excited or nervous we accelerate our speech patterns and the pitch of our voice rises. Don’t mistake enthusiasm for an outright lie.


This is another theory that is probably more cinematic than documentary. Fidgeting in a chair, scratching or grooming gestures are all supposedly signs that someone might be lying. The problem here is that these are also signs of nervousness, boredom or even flirting.

For example playing with jewellery is often seen as a sign of attraction to the person speaking, and a sign that there is something playing on the mind of the speaker while lying. It is more likely to be a simple sign of nervousness.

Here is the problem with trying to turn yourself into a human lie detector during an interview. Many of the signs we are told indicate lying are also, or mainly, signs of nervousness. The fact is, most of us are nervous during interviews and probably use any or all of these non-verbal signals during an interview. Using one or all of these to search for a lying interviewee is fraught with seeing the signs that just aren’t there.

There are ways to spot lying though, if you need to, so get in touch and I can let you know what they are.

Mike Cobb Copywriter

Cobb Communications Ltd.

Vat registered: 372 6181 91

South Woodford- London - United Kingdom - E18