Lie detectors have not been telling the truth: Polygraph tests used for sex offender parole hearings made famous by the Jeremy Kyle Show are little more than ‘junk science’, author claims
- Lie detectors or ‘polygraphs’ are not and never have been reliable, it is claimed
- Author Amit Katwala makes the claim in his book Tremors in the Blood
- Huge discrepancies in results depend on location, race and gender
- The polygraph was created by three men in Berkeley, California in the 1920s
For more than a decade, viewers of The Jeremy Kyle Show tuned in hoping to see a familiar parade of chaotic people – and one notorious feature in particular.
For the show’s cheating partners and feckless fathers, there was no more sobering prospect than the lie detector.
More often than not, the test would reveal that the subject was ‘a liar!’ as the day-time host was fond of shouting. Sometimes they were ‘scum’.
Yet as a Channel 4 documentary revealed last month, even in perfect conditions, with a highly trained expert administering them, Jeremy Kyle’s lie detector tests were only 66 to 70 per cent accurate at best.
They were little more than a pantomime.
We shouldn’t be surprised, says author Amit Katwala in his new book, Tremors in the Blood. For all the immense harm they can cause, lie detectors, or ‘polygraphs’, are not and never have been reliable.
Polygraphs are supposed to work by tracking physiological changes in a person as they answer questions. These could include a rise in blood pressure, sweating on the palms of the hands or a quickening of breath, any of which might indicate that a person is lying
‘There is no way for an examiner to be sure whether a change in blood pressure is due to fear of getting caught, or anxiety about being falsely accused,’ says author Amit Katwala, pictured above
They are supposed to work by tracking physiological changes in a person as they answer questions.
These could include a rise in blood pressure, sweating on the palms of the hands or a quickening of breath, any of which might indicate that a person is lying.
Author Amit Katwala says in his new book, Tremors in the Blood, that for all the immense harm they can cause, lie detectors, or ‘polygraphs’, are not and never have been reliable
The subject’s breathing is measured through rubber tubes on the upper chest and abdomen. Adhesive pads on the hands or fingers measure sweating. A machine called a cardiosphygmograph monitors blood pressure and pulse.
Yet this is little more than ‘junk science’:
‘There is no way for an examiner to be sure whether a change in blood pressure is due to fear of getting caught, or anxiety about being falsely accused,’ says Katwala. ‘There is no single tell-tale sign of deception that holds true for everyone – no Pinocchio’s nose.’
Millions of polygraph tests are conducted every single year. In the United States, they are regularly used by the police and other law enforcement agencies, even though their findings are inadmissible in court.
In Britain, we use polygraphs to assess whether or not sex offenders have breached parole conditions.
This is despite the fact that they are there are huge discrepancies in test results depending on such things as location, race and gender.
Moreover, there have long been ways of beating the machine, including ‘exaggerating the body’s response to the control questions [straightforward ones used to measure a person’s response when not under any pressure] by, for instance, biting the tongue or stepping on a pin hidden in the shoe.’
The subject’s breathing is measured through rubber tubes on the upper chest and abdomen. Adhesive pads on the hands or fingers measure sweating. A machine called a cardiosphygmograph monitors blood pressure and pulse
‘Yes, lie detectors have been used to get confessions from some of the worst criminals,’ says Katwala, ‘but they’ve also perpetrated grave miscarriages of justice.’
The idea that the actions of the body could betray the mind has been around for centuries.
Tremors in the Blood takes its title from a suggestion by the author Daniel Defoe that the racing pulse of a pickpocket would give them away.
‘Guilt carries fear always about with it,’ he wrote in 1730. ‘There is a tremor in the blood of a thief.’
Even the main inventor of the modern-day lie detector started to worry about what he had unleashed.
The polygraph machine was created by three men in Berkeley, California in the early 1920s: August Vollmer, John Larson, a young detective, and a teenager named Leonarde Keeler.
For more than a decade, viewers of The Jeremy Kyle Show (above) tuned in hoping to see a familiar parade of chaotic people – and one notorious feature in particular
For the show’s cheating partners and feckless fathers, there was no more sobering prospect than the lie detector
Vollmer, the town’s chief of police, is often described as the father of modern policing for his efforts to further the use of scientific methods of investigation.
He tasked Larson, who was then the only police officer in America to hold a PhD, with developing a lie detector based on the newly devised – but now standard – systolic blood pressure test.
Vollmer hoped such a device would put an end to the brutal police interrogation methods then widely used.
Keeler, the son of a poet and spiritualist, became involved after he started hanging around the Berkeley police station. At the time, he was known as an amateur magician, yet would he also prove a gifted inventor and played a leading role in developing and refining the contraption.
Larson’s pride in their lie detector soured almost immediately when the machine helped acquit a man called Henry Wilkins, charged with arranging the murder of his wife, in 1922.
The test suggested Wilkens was innocent, yet all other evidence pointed clearly to his guilt. Larson viewed the debacle as ‘a spectacular public failure of the lie detector.’
That same year saw the machines banned from most American courtrooms on the grounds that the technology was too new.
If Larson was relieved, his partner, had other ideas.
Keeler created his own, updated version of the lie detector and continued to promote it among police officers.
The original aim had been to eliminate violence from interrogations, yet Keeler’s recommended methods for getting at the truth combined the use of his lie detector with elements of the old brutality – the ‘third degree’ .
He found commercial outlets, too. In 1931, Keeler struck a deal with the insurance conglomerate Lloyds of London to offer banks a 10 per cent discount on their premiums if they allowed him to test their employees regularly.
Larson was infuriated, saying Keeler had ‘fostered a Frankenstein’s monster’ and their relationship became poisonous.
‘Not only had Keeler taken the bulk of the credit for what was Larson’s invention, he had “prostituted” the polygraph until it was little more than “a racket”,’ writes Katwala.
Soon enough, the lie detector would ‘reach into almost every…aspect of the justice system, and beyond, into business and politics.’
Even Keeler would be unnerved by the treatment of a man called Joseph Rappaport in 1937.
Rappaport had been on death row awaiting the electric chair for the murder of a man due to give evidence against him for heroin-dealing.
As a last-ditch attempt to save the condemned man, his lawyer arranged for Keeler to administer a polygraph.
‘The Rappaport test broke every rule Keeler had laid out,’ writes Katwala. ‘The room was not dark, empty and silent. It was crowded with lawyers and witnesses and journalists hanging around outside.
The test should also have lasted several hours, but was completed in less than one. And Keeler himself was both judge and jury, concluding that: ‘On the basis of my findings, Rappaport is guilty’. He was duly executed the same night.
Yet as Keeler would later admit: ‘The whole atmosphere was like a circus.’
‘John Larson wanted to end the “third degree”, but he ended up creating a psychological form of torture and, as Katwala puts it, a ‘long, dark history of failure and human rights violations’.
Larson spent the rest of his life trying to stop the spread of the machine, but he was fighting an unstoppable tide.
Today, lie detectors creep ever further into British policing, with plans to subject convicted terrorists and domestic abusers to the tests.
Dozens of new lie detection technologies have been invented in recent years, including ‘brain fingerprinting’ and techniques involving artificial intelligence.
But they serve no more than an illusion of justice.
‘It’s been a hundred years since the first polygraph test,’ writes Katwala. ‘And there’s still no such thing as a lie detector.’
- Tremors In The Blood by Amit Katwala is published by Mudlark, priced £20.
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