If only all the liars in the world really did have their pants on fire, life would be so much more straightforward for the rest of us. Being able to spot a big fat falsehood when you’re being told one is the Holy Grail of truthseekers everywhere. Consequently everyone - from the FBI and Scotland Yard to recruiters, bosses, teachers and even exasperated parents - has their own favourite methods of sorting the facts from the, er, alternative facts.
American Indians used to place the suspect’s fingertips in a bowl of water and watch the ripples, the ancient Chinese placed a few grains of rice in the mouth – trembling and a dry mouth both being classic signs of nervousness.
But although there are many methods which claim to be able to identify those who are being less than truthful, is there much evidence that any of them really work?
Here’s a quick MT rundown of the most commonly encountered techniques for identifying mendacity, and how effective or otherwise they might be.
Every Poker player’s favourite, this involves looking for the unconscious movements and ‘tells’ we all make when we’re straying from the path of righteousness. So whether someone is pulling their eyelid, stroking their chin or covering their mouth, it’s supposed to be a sure sign that all they’re holding is a pair of twos, not the full house they’d like you to believe.
Thus it was that Bill Clinton’s touching of his nose when he denied his affair with Monica Lewinsky back in the day was taken as proof positive of his guilt (if only that were all we had to worry about in terms of Presidential veracity now).
The body language approach is plausible and hugely popular, and its appeal is easy to understand – the promise of a list of involuntary physical giveaways which we can read like a dictionary of lying.
Sadly it’s also wrong enough to be effectively useless, because although such tics do exist, not every liar has them and even for those that do, they are all different. One man’s guilty head scratching is another woman’s innocently-itchy scalp.
Thus most studies on this have concluded that unless you already know the person in question pretty well (well enough to have a good idea of whether they’re a liar or not, in fact), trying to spot a liar from their body language is no more effective than guessing.
When you tell a lie, what does it feel like? Your heart beats faster, your palms get sweaty and you feel – and look – anxious. Surely these are unforced and unfakeable physiological responses?
That’s certainly what medical student John Augustus Larson thought when he invented the polygraph or lie detector back in 1921. Using heart rate, blood pressure and the Galvanic Skin Response to measure sweating, polygraphs claim to be able to achieve good results in the hands of a skilled operator.
But even this scientific approach has numerous drawbacks – for one, hooking up your eager new recruit to a lie detector ahead of their probationary review or job interview doesn’t really create the impression of being a progressive and nurturing 21st Century employer.
For another, while occasional or ‘honest’ lies may be exposed this way, a skilled taker of lie-detector tests can beat the machine – stepping on a drawing pin concealed in your shoe is a time-honoured way of confusing the results. This is because what polygraphs really measure is stress rather than lying per se - a good liar may be less stressed than someone unpractised who is telling the truth.
And finally, even the best polygraph results aren’t really good enough. Telling a lie is an intellectual rather than physical act, and claims of success rates up to 90% have been experimentally debunked. Polygraphs are better at spotting a liar than guessing, but not by a big enough margin to make them worthwhile.
Voice pattern analysis
A less intrusive and more up to date version of the lie-detector, voice analysis is popular with many insurance companies. There are commercially available voice pattern analysis systems that claim to be able, if not to spot liars exactly, then at least to be able to say with some certainty when someone is telling the truth.
The key is consistency or otherwise of pitch when speaking, apparently. So when you next call up to make an insurance claim, if your voice passes muster you may find you are fast tracked, but if it doesn’t expect some harder questioning.
While this is one of the more effective technological solutions, the kit is proprietary, expensive and of limited use in individual face-to-face situations.
The Face - eye movements and ‘micro-expressions’
A shifty character doesn’t hold your gaze, right? Wrong – in fact some studies show that liars maintain more eye contact than truthful people, perhaps because they do it on purpose. It’s fibbing 101.
What about the idea, which emerged from the field of Neuro-Linguistic Programming, that right handed people look up and to the right when they are accessing their memories (ie telling the truth) and up and to the left when they are using their imagination (ie lying)? It’s the other way around for left handed people, so you better make sure you get that clear before you start.
It may sound like exactly the sort of thing that Benedict Cumberbatch would do in Sherlock Holmes, but sadly, like the resident of 221B Baker St himself, it’s equally fictional and not borne out by experimental evidence.
Another facial analysis technique got rather more traction - Paul Ekman of the University of California, the doyen of deception studies, created a stir in the noughties with his ‘microexpressions’ theory. This posited that, because liars have to deliberately compose their features to match their stories, fleeting microexpressions best spotted by computer analysis of video footage can give the game away. But attempts to reproduce his results have been patchy.
Listen to what they say
Here we are at last. If you want to spot a liar the clues are in what they say rather than what they do - a few telling words are worth a thousand cheap gestures
To expose a lie you have to catch the liar in the act, finding the holes in their story, tripping them up with logic to expose inconsistencies in their stories. Ask them to describe their version of events in reverse order, for example, and probe them on small irrelevant details about locations, or journeys – apparently irrelevant questions which are hard to anticipate in advance.
The results obtained by an expert questioner can be pretty impressive – a study by Timothy Levine at the University of Alabama found that Federal Agents could unmask lying amongst student experimenters with 90% accuracy. It’s no coincidence that both the police and the judicial services favour open questions and well-structured interviews to check on the verisimilitude of statements.
The drawback here of course is that this is a hard and time consuming business which takes years to learn. It’s also hardly appropriate to haul your colleagues off into a darkened room, shine a lamp in their faces and start giving them the full interrogation treatment, simply to find out whether they stayed home last Monday because they really had food poisoning, or were just recovering from a heavy weekend.
But there are a few less aggressive tips that can help. One good one is to simply ask people how honest they are straight away – it relies on the well-known psychological principle of ‘priming’. Very few will answer ‘Not very’ to this question, and having thus assumed the psychological mantle of honesty even a liar will find it hard to be less than candid after that.
And finally… it takes one to know one
There is one other point which can work in your favour, and that is being an accomplished liar yourself. Many studies – including a fairly recent one by Dr Geoffrey Bird at UCL - have found that practised liars are well above average in their ability to spot others in the act. Probably because they are familiar with the acts of fabrication.
Of course if you aren’t a good liar you could always hire one to help you out. But be careful if you do - how will you know whether to believe them or not?