The false promise of the lie detector
A new generation of high-tech tests is giving authorities undue faith in their power to detect deception, said journalist Amit Katwala in We’ve seen this before, and it usually hasn’t ended well.
WE LEARN TO lie as children, between the ages of 2 and 5. By adulthood, we are prolific. We lie to our employers, to 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, to 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 microexpressions 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 percent of the time—only marginally better than tossing a coin. Some people stiffen and freeze when put on the spot; others become more animated. Liars can spin yarns packed with color 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. 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. But none of these methods has yielded a reliable way to separate fiction from fact.
That could 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 commercialize 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, CEO of Converus, which makes a lie detector based on eye movements and subtle changes in pupil size.
Converus’ 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 U.K., 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 United States. Soon, large-scale lie-detection programs could be coming to the borders of the U.S. and the European Union, where they would flag potentially deceptive travelers for further questioning.
UT 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. Nothing provides a clearer warning about the threats of the new generation of lie detectors than the history of the polygraph, the world’s most widely used deception test.
John Larson, the inventor of the polygraph, came to hate his creation. In 1921, Larson was a 29-year-old rookie police officer working the downtown beat in Berkeley, California. But he had also studied physiology and criminology, and when not on patrol he was in a lab at the University of California, developing ways to bring science to bear in the fight against crime.
In the spring of 1921, Larson built an ugly device that took continuous measurements of blood pressure and breathing rate, and scratched the results onto a rolling paper cylinder. He then devised an interviewbased exam that compared a subject’s physiological response to questions relating to a crime with the subject’s response to control questions such as “Is your name Jane Doe?” As a proof of concept, he used the test to solve a theft at a women’s dormitory.
Larson refined his invention over several years with the help of an enterprising young man named Leonarde Keeler, who envisioned applications for the polygraph well beyond law enforcement. After the Wall Street crash of 1929, Keeler offered a version of the machine concealed inside an elegant walnut box to large organizations so they could screen employees suspected of theft. Not long after, the U.S. government became the world’s largest user of the exam. During the Red Scare of the 1950s, thousands of
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