60 Fun Facts About Lie Detectors

Which of these bodily signals does a standard polygraph record while a person answers questions?

Skin conductivity. Electrodes on the fingertips pick up tiny bursts of sweat, which let the skin carry more current, while an arm cuff and a chest tube track the heart and lungs.

The polygraph made which reference work's 2003 list of 325 great inventions that changed life "for better or worse"?

Encyclopaedia Britannica. Its editors stressed that great did not mean good: the list ran from the printing press to potato chips, and found room for the guillotine, the slot machine and Muzak.

What does the scientific community largely consider polygraphy to be?

Pseudoscience. The machine records arousal such as a racing heart, and no bodily reaction is unique to lying, which is why psychologists say it might better be called a fear detector.

Which body's 2003 review found "little basis for the expectation that a polygraph test could have extremely high accuracy"?

National Academy of Sciences. Its panel warned that overconfidence in polygraph screening was itself a danger to national security, since a test strict enough to catch most spies would also flag crowds of loyal staff.

In a polygraph session, what is the "stim test", staged to convince the subject that the machine works?

A lie told on purpose. The subject picks a card or a number and denies it, then the examiner announces that the chart caught the lie, in some versions helped by a stacked deck.

Which polygraph method, standard in Japanese police work, asks multiple-choice questions such as which of several guns was used?

Guilty Knowledge Test. An innocent suspect has no way of telling which option is the true one, so only someone who was at the scene should react more strongly to it.

Before the word meant a lie detector, Thomas Jefferson prized a "polygraph" that did what?

Copied letters as he wrote them. A second pen linked to his own traced every stroke, so the prolific letter-writer kept a duplicate of what he sent, and historians still mine those copies.

In a 1998 Supreme Court ruling, critics were quoted as rating polygraph accuracy "little better than could be obtained by" what?

The toss of a coin. An airman wanted his court-martial to hear that he had passed a polygraph, and Justice Thomas, noting how experts split on its accuracy, ruled the military could keep such evidence out.

Which CIA officer passed agency polygraphs in 1986 and 1991 while selling secrets to Moscow?

Aldrich Ames. Both tests picked up signs of deception, but the CIA accepted his explanations and passed him each time, and he went on selling secrets until his arrest in 1994.

What did one CIA mole say was the secret of passing the agency's polygraphs?

Confidence and rapport with the examiner. "There's no special magic," the Soviet spy said after his arrest, and polygraphers quoted in the CIA's own review reckoned his examiners had been too friendly to unsettle him.

Why might a person taking a polygraph hide a tack inside one shoe?

To spike the control readings. Examiners compare reactions to harmless control questions with reactions to the ones that matter, so a jab of pain on the controls can make a lie look calm beside them.

In Seinfeld, Jerry is strapped to a police polygraph to hide the fact that he watches which TV show?

Melrose Place. George's only advice is "It's not a lie if you believe it", and Jerry holds out for three questions about the plot before he cracks on the fourth.

In England and Wales, polygraph tests became compulsory in 2014 for which group?

High-risk sex offenders on parole. Nobody is sent back to prison simply for failing, but anything an offender admits during the test about breaking the terms of release can put him there.

In which sport do big-money tournaments often make winners pass a polygraph before they can collect the prize?

Fishing. Nobody referees the catch out on the water, so organisers lean on the test: one failed polygraph cost two walleye anglers about $120,000 in 2021, a year before they were caught hiding weights in fish.

Which American job applicants are most likely to face a lie-detector test, a practice banned for most private employers?

Police recruits. Government employers were left outside the ban on workplace testing, and in a 2007 federal survey about three-quarters of big-city police departments put would-be officers through a polygraph.

Which president said of polygraph tests for his own officials, "I know they'll scare the hell out of people"?

Richard Nixon. White House tapes caught the remark in 1971, and the tactic was an old one: as a congressman in 1948 he dared Alger Hiss to take a lie-detector test.

Which president signed the 1988 law that stops most private employers giving workers lie-detector tests?

Ronald Reagan. Earlier in the decade he had ordered far wider polygraph testing of government staff, and the outcry over that push helped bring on the ban that he ended up signing.

Which industries are exempted from the Employee Polygraph Protection Act?

Security firms and pharmaceutical handlers. Congress let armoured-car and guard companies, and businesses that make or dispense controlled drugs, keep testing new hires because of the cash, valuables and narcotics in their care.

Which 1923 court case about an early lie detector set the "general acceptance" test for scientific evidence in American courts?

Frye v. United States. It was the defence that wanted the test heard: Marston said his blood-pressure readings showed that murder suspect James Frye was innocent, and the judges would not let him testify.

Which figure in the Kennedy assassination story begged the Warren Commission for a lie-detector test and got one in 1964?

Jack Ruby. His first words to the commission were a request for the test, and he took it in the Dallas jail against his lawyer's advice, hoping to show that nobody had put him up to shooting Oswald.

The psychologist who invented the systolic blood pressure deception test later created which comic-book character?

Wonder Woman. William Moulton Marston wrote her under the pen name Charles Moulton and armed her with a golden lasso that makes anyone caught in it tell the truth.

By one family account, who gave William Marston the idea that blood pressure climbs with strong emotion?

His wife. Elizabeth Holloway Marston, a lawyer and psychologist herself, remarked that her blood pressure seemed to climb when she got mad or excited, yet none of his early papers credits her.

According to legend, what does Rome's marble Mouth of Truth do to a liar who slips a hand inside it?

Bites it off. The medieval legend attached itself to a huge marble face that is thought to have begun as an ancient drain cover, and the film Roman Holiday made the test famous worldwide in 1953.

In 1938 Marston fronted adverts claiming lie-detector tests on hundreds of men proved which brand left them less irritable?

Gillette razors. Each man shaved one cheek with a Gillette blade and the other with a rival's, but when the company had John Larson repeat the tests he found no difference at all.

On whom did William Marston first try his blood-pressure test for lying?

His fellow students. At Harvard he had them tell the truth or spin tall tales while he tracked their blood pressure, and he then took the method into Boston's criminal courts.

Which qualification set John Larson, who built the first polygraph in 1921, apart from every other American policeman?

A PhD. Larson had a doctorate in physiology, but he was the worst shot on the Berkeley force and once wrecked two squad cars in a day, and his chief soon had him building a deception test instead.

What became of Margaret Taylor, the first student tested when John Larson's polygraph met a real case in 1921?

She married him. Taylor was a victim, not a suspect: her stolen diamond ring had brought the police to her Berkeley dormitory, and the newspapers loved the romance that followed.

Which nationally renowned Berkeley police chief encouraged Larson's lie-detector work?

August Vollmer. Often called the father of modern policing, he hired college graduates, put his officers on bicycles and then in cars, and in 1921 asked Larson to build him a deception test.

John E. Reid, a Chicago polygraph examiner, gave his name to a widely taught police method for doing what?

Interrogating suspects. The Reid technique piles on pressure and then offers sympathy in order to draw out a confession, and critics blame it for a string of false ones.

John Larson came to regret how police used his polygraph, writing late in life that it had become what?

A Frankenstein's monster. Larson wrote that he had spent more than 40 years fighting the misuse of his own machine, and he died in 1965 still at work on a vast manuscript meant to unmask it.

After World War II, polygraph pioneer Leonarde Keeler was sent to test the workers guarding which secret?

The atomic bomb. Within months of Hiroshima he was polygraphing staff at the Oak Ridge uranium plant, a programme that cost many of them their jobs and ended in 1953 amid accusations of coercion.

What did CIA polygraph expert Cleve Backster wire to his machine in 1966, claiming it reacted to his thoughts?

A houseplant. Backster said the needle leapt when he merely pictured burning a leaf and concluded that plants sense human intentions, but controlled attempts to repeat his results failed.

Polygraph pioneer Leonarde Keeler plays what role in the 1948 film Call Northside 777?

Himself. The film retold a real Chicago case in which his test had helped free a man wrongly convicted of murder, and Keeler ran the machine on the prisoner for the cameras.

Which Italian criminologist tracked suspects' blood pressure during questioning in 1895, among the first uses of an instrument to catch a liar?

Cesare Lombroso. Better known for claiming that born criminals could be told by their looks, he questioned suspects with one hand sealed in a special glove that registered each change in pressure.

In the old ordeal by water, an early test of guilt, which outcome condemned a suspected witch?

Floating. Water, the medium of baptism, was believed to accept the innocent and reject the guilty, so a suspect who sank was cleared and one who bobbed on the surface was condemned.

Former CIA chief Richard Helms told Congress in 1978 that Americans rarely beat the polygraph because they are what?

Raised to tell the truth. Helms added that some Eastern Europeans could pass "without a blip" even when the agency had evidence that they were lying.

The lie detector was sold in the 1920s as science's humane answer to which police practice?

The third degree. Confessions were routinely beaten out of suspects, and Larson's machine promised the truth without violence, though in other hands it became what he called a psychological third degree.

Marston's 1928 "Love Meter" stunt used his lie-detector cuff to compare the reactions of which women to film love scenes?

Blondes and brunettes. He announced that brunettes were the more stirred, and the publicity won him a job at Universal Pictures measuring how audiences responded to films.

Which serial killer passed a polygraph in 1984 and stayed free until DNA evidence led to his arrest in 2001?

Gary Ridgway. The Green River Killer later said he just relaxed and took it, and detectives came to think that a man who felt no stress about his murders gave the machine nothing to read.

Bill Wegerle failed two polygraphs after his wife's 1986 murder in Wichita, until DNA tied the crime to which serial killer?

BTK (Dennis Rader). Wegerle was never charged but lived under suspicion for 18 years; the examiner he had hired himself put the failed test down to the stress he was under.

Ana Montes, a senior Pentagon intelligence analyst, passed a 1994 counterintelligence polygraph while spying for which country?

Cuba. Montes was the Defense Intelligence Agency's senior analyst on Cuba itself, and passing the test let her go on handing its secrets to Havana until her arrest in 2001.

What delivers the verdict on the hand-held PCASS lie detector that US troops began using in Afghanistan in 2008?

A built-in algorithm. The device reads less of the body than a full polygraph and needs no trained examiner, and the Pentagon barred soldiers from using it on American personnel.

What sent Doug Williams, a former police polygraph examiner turned outspoken critic of the test, to prison in 2015?

Coaching people to beat it. Undercover agents came to him posing as clients who needed to pass a federal polygraph, and he was convicted of mail fraud and witness tampering for training them.

Which figure from the Clinton scandals took a polygraph on the 2005 TV series Lie Detector?

Paula Jones. Her sexual harassment suit against the president had ended in a settlement with no apology, and the show offered accusers like her a polygraph as a shot at vindication.

Which British daytime programme did ITV cancel in 2019 after a guest died days after failing its lie-detector test?

The Jeremy Kyle Show. The episode was never broadcast, and in 2024 a coroner found no causal link between the guest's appearance on the programme and his death a week later.

Which Fox game show judged contestants' answers to embarrassing questions against a polygraph they had taken days earlier?

The Moment of Truth. It was adapted from a Colombian hit that was taken off the air in 2007 after a contestant admitted on camera to hiring a hit man to kill her husband.

Which TV science show tried pain and calm thoughts to beat a polygraph, and failed?

MythBusters. Tory Belleci and Grant Imahara were told to take cash from a safe and deny it, with first-class seats on the next trip if they fooled the examiner, and neither managed it.

Chicago neurologist Alan Hirsch claimed that lying sends extra blood to which part of the body, making liars touch it more?

The nose. Hirsch called it the Pinocchio effect after studying Bill Clinton's grand jury testimony, though other researchers say a touched nose may show nothing more than discomfort.

In 1930s Chicago, Leonarde Keeler built a lucrative sideline polygraphing the staff of which businesses?

Banks. He promised managers that staff retested every six months would become their most honest employees, and the idea of routinely screening workers spread from there.

Which brain-scanning method has been sold by US start-ups as a lie detector, though courts have refused it as evidence?

fMRI. Firms such as No Lie MRI and Cephos sold scans said to catch the brain in the act of lying, but judges have kept the results out for want of proof that they work on real suspects.

Which lie-detection method, sold to police forces and insurers, performed no better than guessing in peer-reviewed tests?

Voice stress analysis. The software hunts for strain in a speaker's voice, yet a Justice Department-funded field test in a jail found two popular programs no better than chance at spotting lies about drug use.

Who first gave John Larson's 1921 invention the catchy name "lie detector"?

Newspaper reporters. Larson's own name for it was the cardio-pneumo-psychograph, and it was the San Francisco press, splashing his cases across its pages in 1921, that christened it the lie detector.

In the 1987 case R v Béland, which country's Supreme Court ruled polygraph results inadmissible?

Canada. The ruling shut polygraph results out of the courtroom only: Canadian police may still use the test during an investigation when the person agrees to take it.

What was notable about the FBI polygraph record of Robert Hanssen, who spied for Moscow for some 20 years?

He was never tested. In 25 years the Bureau did not polygraph him once, and after his arrest in 2001 it announced that agents with access to intelligence would now face the machine.

Psychologist Vittorio Benussi's 1914 lie test, a forerunner of the polygraph, tracked changes in what?

Breathing. He reported that the ratio of time spent breathing in to time spent breathing out shifted after a lie, and a tube around the chest became one of the polygraph's standard sensors.

After a 1983 polygraph cost CIA trainee Edward Lee Howard his job, what did he do next?

Defect to Moscow. Reported to have sold CIA secrets to Soviet agents, he gave his FBI watchers the slip in 1985 when his wife drove home with a dummy in his seat, and he surfaced in Moscow a year later.

Which famous defence lawyer hosted the 1983 TV series Lie Detector, on which guests took polygraph tests?

F. Lee Bailey. His guests included Caril Ann Fugate, jailed as the teenage companion of spree killer Charles Starkweather, who took the test on air to back her claim of innocence and was judged truthful.

Which country's Supreme Court in 2010 ruled narcoanalysis, brain mapping and polygraphs illegal without consent?

India. The judges held that forcing such a test on a suspect makes the accused a witness against himself, which the constitution forbids, though leads from a test taken willingly may still be followed up.

Which actor played the lie-spotting scientist in Lie to Me, the Fox drama inspired by Paul Ekman's research?

Tim Roth. His Dr Cal Lightman was loosely based on Ekman, who checked every script as the show's scientific adviser and then published his own notes on what each episode got right and wrong.

Pennebaker's word-counting software found that liars, often anxious or guilty, use more words like which?

Hate. Negative words rose in the false stories, while liars used fewer words such as I and me, as if keeping their distance from the tale, and fewer qualifiers such as but and except.