As ITV’s Liar shows, spotting deception is harder than it looks

Joanne Froggatt and Ioan Gruffudd star in the ITV drama about an alleged rape. ITVpictures

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. 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.

Doctor Andrew Earlham: is he a rapist? ITVpictures

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. 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.