The history of lie detection, from ancient Greece to Love Island That giant of social philosophy, Homer Simpson, once said: “It takes two to lie; one to lie and one to […]

That giant of social philosophy, Homer Simpson, once said: “It takes two to lie; one to lie and one to listen.” Although the line was delivered in jest, there is truth in it. Lying is an active process that requires one party to accept a falsehood as truth.

But how can you tell if someone is lying to you? We live in an age of ‘fake news’, ‘gaslighting’, and ‘alternative facts’, and getting to the truth seems harder than ever.

There are many different types of deception, and we’re all guilty of deceit at one time or another: “I bought these shoes in the sale”, “I found your father’s thoughts on pipe lagging fascinating”, “Of course I orgasmed, you’re a stallion, darling”, etc. There are little white lies, lies of omission, beneficial lies, malicious lies and lies of deception.

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Another type of liar

In 1986, Harry Frankfurt added a further classification of a liar in his essay on ‘bullshitting’. Frankfurt reasoned that a liar is different to a bullshitter as the liar cares about a specific truth remaining concealed, whereas the bullshitter cares less about a truth than they do about impressing whoever is listening. The nasty ‘pants on fire’ type of lie require three distinct components; the lie must communicate some information, the liar fully intends to deceive, and the liar knows what they are saying is not true.

‘Reading a person’s physical response to spot a lie is actually a very ancient technique of truth-seeking’

As long as people have been telling fibs, there have been methods of lie detection. The sad truth is that there really isn’t any foolproof way of sniffing out a porkie pie – not yet anyway.

Even the modern-day polygraph is considered so unreliable that it is rarely used in a court of law. The polygraph measures levels of arousal – respiration, pulse rate, skin response, etc. – it does not measure the truth. If you don’t happen to have a portable polygraph, or a lie detecting app, there is an abundance of information available on body language and the involuntary ‘tells’ we make, to help you navigate your way through the various tangled webs of deceit. But, reading a person’s physical response to spot a lie is actually a very ancient technique of truth-seeking.

For example, the Greek physician Erasistratus (300-250 B. C.) was said to have proven Prince Antiochus was desperately in love with his father’s new wife, Stratonice, by noting his pulse increased significantly whenever the Queen’s name was mentioned, despite his insistence that he did not have the hots for his stepmother.

The ancient Hindu text, ‘Papyrus Vedas’, dating from 900 B.C., draws on body language techniques to spot someone lying about poisoning people:

‘A person who gives poison may be recognized. He does not answer questions, or they are evasive answers; he speaks nonsense, rubs the great toe along the ground, and shivers; his face is discoloured; he rubs the roots of the hair with his fingers; and he tries by every means to leave the house’.

The methods used in lie detection

Another method practised in China around 1000 B.C. involved filling the suspect’s mouth with dry rice. After being left for a while, the accused then spat the rice out and if the rice was found to be completely dry, then they were guilty of lying. Bonkers as this may seem, there was method in the madness. The theory was the anxiety and fear felt by the liar would result in a dry mouth, and dry rice. (This also works with dried pasta, but you will be thrown off Tinder for turning up to all new dates brandishing a packet of supernoodles and a stopwatch.)

‘Trial by ordeal’ has no footing in scientific rigour but was used throughout Europe until the 17th century. The theory here was that God would not allow an innocent to be found guilty and would intercede to save them from the ordeal being inflicted. Common trials have included throwing trussed up people into water to see if they float, forcing someone to eat bread to see if they choked, and having the accused walk over red-hot pokers to see if they lived.

Economist Peter Leeson suggested these trials may have had some success in sorting the innocent from the guilty, but not because of any divine intervention. Leeson argued the belief in God and punishment was so strong, only the innocent would agree to submit to them.

Water-ordeal. Engraving, 17th century. (Wikicommons)

In the nineteenth century, phrenology was touted as a scientific method of lie detection. Phrenology taught that different points of the brain are responsible for various behaviours – including criminal tendencies. Repeated behaviour would cause the brain to strengthen in one area, which would, in turn, create distinct lumps and bumps on the skulls. Phrenologists claimed to be able to read these lumps and bumps to determine a wrong’un. Franz Joseph Gall (1758-1828), the founder of phrenology, travelled the world shaving criminal’s heads, reading bumps and outing compulsive liars. By the end of the nineteenth-century phrenology had been discredited.

The first modern lie detector was Cesare Lombroso’s ‘hydrosphygmograph glove’, described in his book, ‘Criminal Man’ (1876):

‘The glove is filled with air, and the greater or smaller the pressure exercised on the air by the pulsation of the blood in the veins of the hand acts on an aerial column… [T]his chamber supports a lever carrying an indicator which rises and falls with the greater or slighter flow of blood in the hand’.

‘Vittorio Benussi (1878-1927) found that breathing changes when we lie, and called this the ‘inspiration-expiration ratio’

According to the second edition of this work, Lombroso had used his glove successfully in several criminal proceedings. While Lombroso was focusing on hands and blood pressure, his contemporary Vittorio Benussi (1878-1927) found that breathing changes when we lie, and called this the ‘inspiration-expiration ratio’.

It was William M. Marston (of ‘Wonder Woman’ fame) in 1915 who brought all the existing research together and created a systolic blood pressure test that recorded changes in blood pressure and respiration rates. Marston’s work formed the basis of the first polygraph or lie detector, designed by John Larson and Leonard Keeler a few years later in 1921. The Larson / Keeler polygraph recorded respiratory rate, blood pressure, and the bioelectric reactivity of the skin. Larson later developed the R/I (relevant/irrelevant) technique of polygraph interviewing where questions relevant to the crime are interspersed with irrelevant ones to better gauge a change in arousal rates.

The reliability of the test

Leonarde Keeler (1903–1949) testing his improved lie-detector on Kohler, a former witness for the prosecution at the 1935 trial of Bruno Hauptmann. (Wikicommons)

Almost as soon as it was invented there were challenges to the reliability of the polygraph. In the landmark 1923 case of Frye v United States, it was ruled the polygraph could only be used in court if it had “sufficiently established to have gained general acceptance” in the scientific community.

It’s almost 100 years later and, despite the extensive work done by numerous daytime talk shows, the polygraph still has not gained general acceptance by the scientific community. However, polygraphs are regularly used in criminal investigations in the US, and are used in the UK to monitor sex offenders after their release.

‘The annual lie detector test has not yet been unleashed on this year’s ‘Love Island’ contestants, but will no doubt add to the drama when it is.’

Despite its unreliability, the lie detector has gained something of a mythical status in popular culture. In ‘The Truth Machine: A Social History of the Lie Detector’ (2012), Geoffrey C. Bunn reads the history of the lie detector against the rise of mass culture and the information age. He argues the polygraph has become an icon of social control, and he may be right. In the wake of Facebook data scraping, Donald Trump, Russian electoral fraud, Brexit, and trial by social media, the polygraph offers a remote, but very welcome, chance of beginning to untangle the knot of ‘alternative facts’ we’re faced with every day.

The annual lie detector test has not yet been unleashed on this year’s ‘Love Island’ contestants, but will no doubt add to the drama when it is. However, given that some scientists have placed the reliability of the test as low as 50 per cent, we really may as well be asking them to sit in a corner spitting rice.