Why spotting a liar is harder than you think

Posted on August 22, 2012


Why spotting a liar is harder than you think


We live in a world blighted by crime, deception and fraud. With governments fabricating excuses to go to war, bankers manipulating interest rates to fill their own pockets, and the media awash with tales of adultery, it’s hard to know who to trust.


In this climate of institutionalised dishonesty, confidence in political leaders, and the businesses that dominate the economy, may have been eroded beyond repair. But we cling to the idea that, in our day-to-day life, we can at least tell when another individual is lying to us. We’re seduced by the idea that there are certain signals that reveal when someone isn’t telling the truth, and we convince ourselves that learning to read these signs will allow us to avoid being cheated or tricked, or maybe even win a game of poker.


Taking this a step further, we’ve all seen polygraph tests paraded on daytime TV, apparently settling arguments about who fathered a child, or whether an infidelity took place. In fact, polygraph tests have even been admitted as evidence in court. In truth, though, there are all kinds of problems with the techniques and technology of lie detection. In this article, we take a closer look at some of the illusions that underpin the pseudo-science of lie detection.


Speech and Body Language

According to some so-called experts, the way people speak, and the gestures and expressions they use, can reveal whether or not they’re telling the truth. The verbal and non-verbal signals commonly associated with lying include fidgeting, mumbling, throat clearing, avoiding eye contact and touching one’s face. Whilst many or all of these signals may be present when someone is lying, they don’t prove anything. In fact, controlled studies have shown that people who have undertaken behaviour analysis training (such as police interrogators) are actually less able to tell the difference between genuine and false denials, when compared with people who are not trained to spot these signals. Furthermore, a recent study by a team of British and Canadian psychologists debunked the link between eye movements and lying.


Polygraph Machines

Polygraph lie detectors, which measure things like perspiration and pulse rate, aren’t just used on talk shows by the likes of Jerry Springer and Jeremy Kyle; the FBI and CIA use them to screen applicants, and the British government has just announced that probation officers will be able to send paroled sex offenders back to prison on the basis of failed polygraph tests. But, so far, the scientific evidence has shown that these tests are only slightly better than random chance at detecting lies. In real-world situations, sweating, or an increased heart rate, could easily be the result of fear rather than guilt, whilst, in lab tests designed to gauge the reliability of these tests, variables such as observer bias have rendered the results essentially meaningless.


New Techniques


Although the methods used in an effort to detect lies in the past have been flawed, scientists and security agencies remain committed to the concept of lie detection. There are techniques including functional magnetic resonance imaging (fMRI) and electroencephalography (EEG), which measure brain activity, that approach the problem in a different way. But, once again, critics question the reliability of such technology. And that’s before one even considers the ethical issues raised by the development of technologies that promise to read people’s minds.


Still Think You Can Spot a Liar?


Clearly, spotting a liar is a lot harder than is often made out. However, that’s not to say that people don’t ever reveal things unintentionally through the sound of their voice or their physical behaviour. Many people find that studying the way humans communicate helps them to read between the lines, and get a better sense of the emotion and meaning behind the things people say and do, even if it can never offer a reliable means of establishing truth. If you’re interested in learning more about interpreting people’s behaviour and becoming a more effective communicator yourself, you may with to try something like NLP training. Just don’t kid yourself that you’re some kind of magical human truth wizard; at the end of the day, we’re all fallible.

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