Erikka Askeland: Old donkey of truth still has legs

TV presenter Jeremy Kyle. Picture: Robert Perry

For the Kyle uninitiated, the programme features dramatic confrontations between friends and families whose denizens probably would have benefitted greatly if the NHS fully covered regular trips to the dentist.

Why folk are so keen on airing on television their dark concerns about whether the child is theirs, or their spouse has committed adultery, is a question for another day. But what I gleaned from that hour was they were craving certainty. Because they all, to a man and woman, seemed willing to sacrifice what passed for their dignity in exchange for something that their appearance on the show offered – the test, which would answer irrevocably the vexing mystery that had been driving them to extreme behaviour.

Some got a DNA test, while others were subject to a lie detector. And while the former seems scientifically beyond reproach, I was pretty sure that the polygraph had been pretty much rubbished as way of telling if someone was telling porky pies. Yet there was Mr Kyle, leering menacingly in front of a lad accused of stealing his brother’s holiday money, shouting, “You are a liar” on the basis that he had failed it.

The trouble with polygraphs, which measures signs of nervousness, is that they have been shown to be more or less effective when someone has been proved to be lying. But they are prone to giving “false positive” results.

As long as there have been humans there has been demand for a sure-fire way of finding out a lie. Folklore tells us of the “donkey of truth”, where the defendant was ushered blindfolded into a tent and told that the animal inside would bray if its tail was pulled and the person was telling the truth.

Once leaving the tent, his or her inquisitors would know whether the person was guilty or not regardless of what the donkey did. That’s because the one keen to clear her name would have grasped the tail – which, most importantly, had been inked up, while the liar wouldn’t have touched it. So the miscreant that emerged with clean hands was deemed guilty. And the scheme would have been pretty foolproof too, until the liars caught onto the trick.

We need truth devices because we are pretty bad at spotting mendacity. A recent study found people who were seasoned at interviewing job hopefuls were no better at telling the fake interviews – where subjects made up their experience – than others. Even the ones who were aware of the non-verbal cues people give off when being economical with the actualité only slightly improved their scores.

A-ha. Yes, there are ways of telling – but not in the way you might think. Many still believe that shifty eyes and fidgeting are sure signs someone’s being deceptive, but they would be wrong.

The science of micro-expressions, fleeting emotions that unconsciously play across the face, has been popularised by a professor of psychology at San Francisco State University, Dr David Matsumoto. He realised, during a paralympics event, that congenitally blind athletes showed the same expressions of joy when they won despite never having seen someone else’s mug. Expressions are thus innate and although we can try to pull a straight face, our bodies often betray or “leak” the truth what we really know and feel.

But the trouble with this field of detection is that it is hard to observe, and even more difficult to interpret.

So there remains the lie detector. Local authorities and insurance firms are using a techie variation on the polygraph, known as voice risk analysis software. This promises to indicate if people are making fraudulent claims just by their tone of voice on the phone. This is despite the fact such stuff has been debunked by academics as being no more accurate than astrology.

But there is a strange phenomenon when it comes to the lie detector, known to psychologists as the “bogus pipeline to the truth”. Like the donkey in the tent, if people believe it is true they are more likely to be honest, even to the point of confession. But it only works if people truly believe the machine can reveal what is inside their minds. So don’t tell anyone on Jeremy Kyle.