AI and brain-scanning technology could soon make it possible to reliably detect when people are lying. But do we really want to know?

AI and brain-scanning technology could soon make it possible to reliably detect when people are lying.

We learn to lie as children, between the ages of two and five. By adulthood, we are prolific. We lie to our employers, our partners and, most of all, one study has found, to our mothers. The average person hears up to 200 lies a day, according to research by Jerry Jellison, a psychologist at the University of Southern California. The majority of the lies we tell are “white”, the inconsequential niceties – “I love your dress!” – that grease the wheels of human interaction. But most people tell one or two “big” lies a day, says Richard Wiseman, a psychologist at the University of Hertfordshire. We lie to promote ourselves, protect ourselves and to hurt or avoid hurting others.

The mystery is how we keep getting away with it. Our bodies expose us in every way. Hearts race, sweat drips and micro-expressions leak from small muscles in the face. We stutter, stall and make Freudian slips. “No mortal can keep a secret,” wrote the psychoanalyst in 1905. “If his lips are silent, he chatters with his fingertips. Betrayal oozes out of him at every pore.”

Even so, we are hopeless at spotting deception. On average, across 206 scientific studies, people can separate truth from lies just 54% of the time – only marginally better than tossing a coin. “People are bad at it because the differences between truth-tellers and liars are typically small and unreliable,” said Aldert Vrij, a psychologist at the University of Portsmouth who has spent years studying ways to detect deception. Some people stiffen and freeze when put on the spot, others become more animated. Liars can spin yarns packed with colour and detail, and truth-tellers can seem vague and evasive.

Humans have been trying to overcome this problem for millennia. The search for a perfect lie detector has involved torture, trials by ordeal and, in ancient India, an encounter with a donkey in a dark room. Three thousand years ago in China, the accused were forced to chew and spit out rice; the grains were thought to stick in the dry, nervous mouths of the guilty. In 1730, the English writer Daniel Defoe suggested taking the pulse of suspected pickpockets. “Guilt carries fear always about with it,” he wrote. “There is a tremor in the blood of a thief.” More recently, lie detection has largely been equated with the juddering styluses of the polygraph machine – the quintessential lie detector beloved by daytime television hosts and police procedurals. But none of these methods has yielded a reliable way to separate fiction from fact.

That could soon change. In the past couple of decades, the rise of cheap computing power, brain-scanning technologies and artificial intelligence has given birth to what many claim is a powerful new generation of lie-detection tools. Startups, racing to commercialise these developments, want us to believe that a virtually infallible lie detector is just around the corner.

Their inventions are being snapped up by police forces, state agencies and nations desperate to secure themselves against foreign threats. They are also being used by employers, insurance companies and welfare officers. “We’ve seen an increase in interest from both the private sector and within government,” said Todd Mickelsen, the CEO of Converus, which makes a lie detector based on eye movements and subtle changes in pupil size.

Converus’s technology, EyeDetect, has been used by FedEx in Panama and Uber in Mexico to screen out drivers with criminal histories, and by the credit ratings agency Experian, which tests its staff in Colombia to make sure they aren’t manipulating the company’s database to secure loans for family members. In the UK, Northumbria police are carrying out a pilot scheme that uses EyeDetect to measure the rehabilitation of sex offenders. Other EyeDetect customers include the government of Afghanistan, McDonald’s and dozens of local police departments in the US. Soon, large-scale lie-detection programmes could be coming to the borders of the US and the European Union, where they would flag potentially deceptive travellers for further questioning.

But as tools such as EyeDetect infiltrate more and more areas of public and private life, there are urgent questions to be answered about their scientific validity and ethical use. In our age of high surveillance and anxieties about all-powerful AIs, the idea that a machine could read our most personal thoughts feels more plausible than ever to us as individuals, and to the governments and corporations funding the new wave of lie-detection research. But what if states and employers come to believe in the power of a lie-detection technology that proves to be deeply biased – or that doesn’t actually work?

And what do we do with these technologies if they do succeed? A machine that reliably sorts truth from falsehood could have profound implications for human conduct. The creators of these tools argue that by weeding out deception they can create a fairer, safer world. But the ways lie detectors have been used in the past suggests such claims may be far too optimistic.

For most of us, most of the time, lying is more taxing and more stressful than honesty. To calculate another person’s view, suppress emotions and hold back from blurting out the truth requires more thought and more energy than simply being honest. It demands that we bear what psychologists call a cognitive load. Carrying that burden, most lie-detection theories assume, leaves evidence in our bodies and actions.

Lie-detection technologies tend to examine five different types of evidence. The first two are verbal: the things we say and the way we say them. Jeff Hancock, an expert on digital communication at Stanford, has found that people who are lying in their online dating profiles tend to use the words “I”, “me” and “my” more often, for instance. Voice-stress analysis, which aims to detect deception based on changes in tone of voice, was used during the interrogation of George Zimmerman, who shot the teenager Trayvon Martin in 2012, and by UK councils between 2007 and 2010 in a pilot scheme that tried to catch benefit cheats over the phone. Only five of the 23 local authorities where voice analysis was trialled judged it a success, but in 2014, it was still in use in 20 councils, according to freedom of information requests by the campaign group False Economy.

The third source of evidence – body language – can also reveal hidden feelings. Some liars display so-called “duper’s delight”, a fleeting expression of glee that crosses the face when they think they have got away with it. Cognitive load makes people move differently, and liars trying to “act natural” can end up doing the opposite. In an experiment in 2015, researchers at the University of Cambridge were able to detect deception more than 70% of the time by using a skintight suit to measure how much subjects fidgeted and froze under questioning.

The fourth type of evidence is physiological. The polygraph measures blood pressure, breathing rate and sweat. Penile plethysmography tests arousal levels in sex offenders by measuring the engorgement of the penis using a special cuff. Infrared cameras analyse facial temperature. Unlike Pinocchio, our noses may actually shrink slightly when we lie as warm blood flows towards the brain.

In the 1990s, new technologies opened up a fifth, ostensibly more direct avenue of investigation: the brain. In the second season of the Netflix documentary Making a Murderer, Steven Avery, who is serving a life sentence for a brutal killing he says he did not commit, undergoes a “brain fingerprinting” exam, which uses an electrode-studded headset called an electroencephalogram, or EEG, to read his neural activity and translate it into waves rising and falling on a graph. The test’s inventor, Dr Larry Farwell, claims it can detect knowledge of a crime hidden in a suspect’s brain by picking up a neural response to phrases or pictures relating to the crime that only the perpetrator and investigators would recognise. Another EEG-based test was used in 2008 to convict a 24-year-old Indian woman named Aditi Sharma of murdering her fiance by lacing his food with arsenic, but Sharma’s sentence was eventually overturned on appeal when the Indian supreme court held that the test could violate the subject’s rights against self-incrimination.

Source: The Guardian

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