Don’t assume people tell the truth

The smash-hit ITV drama Liar has left viewers up and down the country scrutinising their screens, trying to work out which character has been telling the truth.

The series tells the story of Laura, who goes on a date with handsome doctor Andrew, only to wake up the next morning believing she was raped.

Most people like to think that if they found themselves in a genuine situation where they needed to tell the difference between fact and fiction they would be able to.

The smash-hit ITV drama series Liar tells the story of Laura, who goes on a date with handsome doctor Andrew, only to wake up the next morning believing she was raped

The smash-hit ITV drama series Liar tells the story of Laura, who goes on a date with handsome doctor Andrew, only to wake up the next morning believing she was raped


Dr Chris N. H. Street, a researcher at the University of Huddersfield, has been studying the cognition of social conflict.He says that people are biased to believe that what others are telling us is the truth.

Researchers call this the ‘truth bias.’

Dr Street argues people are truth biased no because of an error nor an uncontrollable way of thinking – rather, the bias is an indication of how people are making smart and informed guesses.

Because the clues that someone is lying are very unreliable, people usually have to guess if someone is lying or not.

People usually make this guess by relying on more general information about the context – for example, it’s been shown in studies that most people tell the truth most of the time in our daily lives.

But research shows that when it comes to spotting a liar, most people are very inaccurate – they might as well just flip a coin to try and decide.

It also seems that most of us tend to believe others are telling the truth more often than they actually are.

This is called the ‘truth bias’.

And this bias may in part be because research has shown the majority of people tell the truth most of the time.

So if there is no evidence otherwise, it makes sense to guess someone is telling the truth because that’s more likely.

Why lie?

Although people’s reasons for lying vary along with the severity of the lie – from getting out of a meal with a friend to lying about a criminal offence – in the end there is always some goal to achieve.

In short, people lie because it is more likely to get them what they want compared with telling the truth.

But of course, this only works when the risk of getting caught lying is low – research has shown that people tend to weigh up the risks of getting caught before deciding whether or not to lie.

And while most people like to think that it’s only others who are deceptive – and that they never lie – research shows otherwise.

So as much as we might not want to admit it (even to ourselves), we all lie – at least a little bit.

Spotting a liar

My research shows that the reason why most people are so bad at spotting a fibber is because liars are skilled at covering up their lies.

And as we know, most people tend to only lie when they feel it is unlikely they will get caught – so lies are almost by definition difficult to spot.

People are biased to believe that what others are telling us is the truth. Researchers call this the ‘truth bias’

Though of course this isn’t always the case.

Imagine a police officer who has access to CCTV footage of a suspect entering a bank.

Dr Chris N. H. Street (pictured), a researcher at the University of Huddersfield, has been stuyding the cognition of social conflict

If the suspect denies being in the bank, chance are they aren’t exactly trustworthy.

And research shows that the ‘strategic use of evidence’, such as withholding additional information or footage until you hear from a suspect, can help to achieve a high level of accuracy when it comes to telling truth from lies.

But in terms of fine tuning your own lie detector, there isn’t really an awful lot you can do, other than the obvious – ask questions and look for inconsistencies with known facts.

If you don’t have that information, try to stop yourself from assuming people are telling the truth, and keep an open mind.

Ultimately, though, lie detection is a tough game.

But in the future science might make it a whole lot harder to be a good liar and get away with it.


Body language expert Judi James has revealed the key signs to look out for if you’re concerned someone is being economical with the truth:The big pause: Lying is quite a complex process for the body and brain to deal with. First your brain produces the truth which it then has to suppress before inventing the lie and the performance of that lie.

This often leads to a longer pause than normal before answering, plus a verbal stalling technique like ‘Why do you ask that?’ rather than a direct and open response.

The eye dart: Humans have more eye expressions than any other animal and our eyes can give away if we’re trying to hide something.

When we look up to our left to think we’re often accessing recalled memory, but when our eyes roll up to our right we can be thinking more creatively. Also, the guilt of a lie often makes people use an eye contact cut-off gesture, such as looking down or away.

The lost breath: Bending the truth causes an instant stress response in most people, meaning the fight or flight mechanisms are activated.

The mouth dries, the body sweats more, the pulse rate quickens and the rhythm of the breathing changes to shorter, shallower breaths that can often be both seen and heard.

Overcompensating: A liar will often over-perform, both speaking and gesticulating too much in a bid to be more convincing. These over the top body language rituals can involve too much eye contact (often without blinking!) and over-emphatic gesticulation.

The poker face: Although some people prefer to employ the poker face, many assume less is more and almost shut down in terms of movement and eye contact when they’re being economical with the truth.

The face hide: When someone tells a lie they often suffer a strong desire to hide their face from their audience. This can lead to a partial cut-off gesture like the well-know nose touch or mouth-cover.

Self-comfort touches: The stress and discomfort of lying often produces gestures that are aimed at comforting the liar, such as rocking, hair-stroking or twiddling or playing with wedding rings. We all tend to use self-comfort gestures but this will increase dramatically when someone is fibbing.

Micro-gestures: These are very small gestures or facial expressions that can flash across the face so quickly they are difficult to see. Experts will often use filmed footage that is then slowed down to pick up on the true body language response emerging in the middle of the performed lie.

The best time to spot these in real life is to look for the facial expression that occurs after the liar has finished speaking. The mouth might skew or the eyes roll in an instant give-away.

Heckling hands: The hardest body parts to act with are the hands or feet and liars often struggle to keep them on-message while they lie.

When the gestures and the words are at odds it’s called incongruent gesticulation and it’s often the hands or feet that are telling the truth.

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