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How to Tell Who is Lying to You - The Latest Psychological Research

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Syria's UN envoy has condemned what he called a "tsunami of lies" being told by some members of the United Nations Security Council. Bashar Jaafari is arguing Syrian forces were not to blame for a massacre in which 108 people were killed and 300 injured, but for which the UN blames heavy weapons by Syria's government.

In the face of what can seem like a 'tsunami of lies' on every horizon, we appear in dire need of the skill to spot who is actually telling the truth, to keep our heads above the rising tide. For example, the Leveson Inquiry continues to pursue the facts, yet some newspapers now prefer body language analysis when reporting what witnesses have said, apparently in order to glimpse the reality behind the words.

The latest psychological research on deception detection casts doubt as to whether the way the inquiry poses questions is likely to penetrate the defences of dissemblers.

It may come as a surprise that so-called experts are not good at spotting lying, but a review of 39 scientific studies by Professor of Applied Social Psychology, Aldert Vrij, a world authority on the science of deception, reveals an average accuracy rate of just 56.6% - in other words for over a third of the time lies go undetected. Men and women are no better than each other, Professor Vrij reports, and professional lie catchers such as police officers and customs officers are generally no superior to the lay public in detecting deceit.

One of the reasons we are so bad at spotting deception is there are widespread erroneous beliefs about what behaviours betray the telling of lies. For example, one of the commonest mistakes is that liars increase their body movements, the famous shiftiness, gaze aversion and fidgeting of a dissembler. In fact scientific research on this demonstrates the opposite is more true, liars more often decrease their body movements and tend to hold your gaze.

So can we learn from the psychological research into deception, to improve our ability to detect deception, and can these techniques help inquiries such as Leveson to sift fake answers from truth?

In fact there are many psychological strategies pioneered by experts such as Professor Vrij, who is based at the University of Portsmouth, which would help us all become better lie detectors, and many are detailed in his book Detecting lies and deceit: Pitfalls and opportunities (published by Wiley). Space only allows two to be mentioned here, both of which are notable in their absence from the style of questioning thus far in the Leveson Inquiry.

The first is called the 'Baseline Method', and it's based on the important principle that there is in fact no one behaviour that is universally characteristic of liars, but when any particular individual starts to stray from the truth, various cognitive, emotional and physiological processes kick in, which it is possible to detect.

But you can only spot these if you already have the 'baseline' of how someone behaves when they are telling the truth, and then compare that with the moment when you wonder if they have begun to lie.

Professor Vrij quotes a real-life example of a videotaped police interview with a murderer being asked to describe a whole day, not just the key moment the police believed he committed the homicide. Detailed analyses of the tape revealed a sudden change in behaviour as soon as the suspect started to describe his activities during the particular time of forensic interest. It was the contrast between his description of times when he didn't have to lie as he spoke, as no crime had occurred then, compared with the period the police were most interested in which was significant.

During his description of the part of the day when the police knew the murder had occurred, he spoke slower, added more pauses, and made fewer movements, compared to the baseline, the other parts of the day the police had patiently asked in detail about. He met the victim and killed her during the period where his behaviour changed when covering up.

Professor Vrij cautions that often interrogators misunderstand the true subtlety of this research finding and misapply it. Crucial in the use of the baseline technique is that correct parts of the interview are compared. Unfortunately, too often in police interviews 'small talk' at the beginning is used to establish a baseline. This is an incorrect way of deploying the technique as small talk and the actual police interviews are totally different situations. Both the guilty and innocent tend to change their behavior the moment the actual interview starts, not least because both are bound to become more nervous then.

Another psychological technique for better spotting lies pioneered by Professor Vrij and colleagues is called 'Devil's Advocate'. Interviewees are first asked questions inviting them to argue in favour of their personal view (eg "What are your reasons for supporting the US in the war in Afghanistan?"). This is followed by a Devil's Advocate question that asks interviewees to argue against their personal view (eg "Playing Devil's Advocate, is there anything you can say against the involvement of the US in Afghanistan?").

The 'Devil's Advocate Question' is an attempt to flush out what the interviewee truly believes, as if they are lying about their position on the war in Afghanistan, for example, the Devil's Advocate Question is actually what they really believe, but are covering up. As we think more deeply about, and are more able to generate, reasons that support rather than oppose our beliefs, this leaks out during the answer to the Devil's Advocate Question.

In effect, for liars the Devil's Advocate approach is a set-up where they first lie when answering the opinion-eliciting question, and are then lured into telling the truth when answering the Devil's Advocate question. Normally we aren't very good at giving reasons for a position we don't hold, so most people aren't good at being a 'devil's advocate' in this situation. Liars however are caught out because they now tend to give fuller and better answers in response to being asked to be a devil's advocate than non-liars. Using this technique Professor Vrij and colleagues found 75% of truth tellers and 78% of liars could be classified correctly.

But before we are too quick to judge those in the headlines who find themselves accused of lying, the psychological research indicates that ordinary people tell an average of 1.5 lies a day, but this rate can climb dramatically because how likely you are to deceive depends a lot on the situation you find yourself in. For example, studies find that 83% of students would lie to get a job and 90% are willing to lie on first dates to secure favorable impressions.

Raúl López-Pérez and Eli Spiegelman, academic Economists, point out in their paper entitled Why do people tell the truth? Experimental evidence for pure lie aversion, soon to be published, that one of the downsides of living in an acquisitive free market economy is how much we constantly gain materially by providing false information.

From doing our accounts, auditing, insurance claims, job interviews, negotiations, regulatory hearings, tax compliance, and all sorts of other situations we stand to gain if we lie, these economists point out, and indeed we are penalised if we are honest.

Given all the incentives to lie, López-Pérez and Spiegelman from the Universidad Autónoma de Madrid and Université de Québec a Montréal, believe the more interesting question is not why do we lie, but instead, why do some people tell the truth? Perhaps more precisely, why do some stick to the truth even when it's not in their interests?

In their research 38.76% of subjects taking part in their experiments, chose to tell the truth even when they would suffer a penalty as a result. López-Pérez and Spiegelman come up with an intriguing new theory of lying where they believe there is a minority of the population who suffer from what they call 'pure lie aversion'. This means some tell the truth because of an innate abhorrence for lying.

López-Pérez and Spiegelman argue this is a significant force behind honesty which has hitherto been neglected by science. It's certainly a factor we should perhaps look for more in our politicians, but then again, maybe we get the lying leaders we deserve because we're constantly seduced into voting for the best con artists. Perhaps all electorates should become more educated in Professor Vrij's techniques before casting their vote.

López-Pérez and Spiegelman also found that those who lied were significantly more likely to believe that others would lie as well. This means the more our politicians and authority figures, even friends or colleagues lie, the more deception will continue spreading.

Dr Raj Persaud is a Consultant Psychiatrist based in London and Aldert Vrij (PhD) is a Professor of Applied Social Psychology who has published almost 400 articles and 7 books on the above topics, including his 2008 book Detecting lies and deceit: Pitfalls and opportunities (published by Wiley), a comprehensive overview of research into nonverbal, verbal and physiological deception and lie detection.

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