Lie Detectors Trivia
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60 free Lie Detectors trivia questions with answers — science & nature quiz, new questions added Aug 2026.
The lie detector is an American invention that most of the world's courts refuse to trust, and this quiz explains why. It starts with the machine itself: what a polygraph actually records, the control question and guilty knowledge tests, the stim test examiners use to unsettle suspects, and the countermeasures a KGB handler taught Aldrich Ames. It then goes back to the inventors: William Moulton Marston and the blood-pressure test his wife inspired (and the Wonder Woman lasso he dreamed up later), John Larson's Berkeley machine of 1921 and the sorority thefts it was first used on, and Leonarde Keeler's portable version that the FBI bought. The second half covers the law and the culture: Frye v. United States and the general acceptance standard, the 1988 Employee Polygraph Protection Act, the National Academy of Sciences verdict, the spies and serial killers who passed, the innocent man who failed, and lie detectors on television from the 1950s to Jeremy Kyle and The Moment of Truth. Easy questions ask what the machine measures; the expert tier asks for dates, cases and the people behind them. Every answer was checked against Wikipedia's articles on the polygraph, lie detection, Marston, Larson, Keeler and related cases, and the supporting sentence is attached to each question. If you like this, try our quizzes on forensic science and famous spies.
30 of 60 questions with answers and explanations. Play the quiz
Q 01Which of these bodily signals does a standard polygraph record while a person answers questions?
Skin conductivity
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.
Q 02The polygraph made which reference work's 2003 list of 325 great inventions that changed life "for better or worse"?
Encyclopaedia Britannica
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.
Q 03What does the scientific community largely consider polygraphy to be?
Pseudoscience
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.
Q 04Which body's 2003 review found "little basis for the expectation that a polygraph test could have extremely high accuracy"?
National Academy of Sciences
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.
Q 05In a polygraph session, what is the "stim test", staged to convince the subject that the machine works?
A lie told on purpose
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.
Q 06Which polygraph method, standard in Japanese police work, asks multiple-choice questions such as which of several guns was used?
Guilty Knowledge Test
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.
Q 07Before the word meant a lie detector, Thomas Jefferson prized a "polygraph" that did what?
Copied letters as he wrote them
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.
Q 08In 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
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.
Q 09Which CIA officer passed agency polygraphs in 1986 and 1991 while selling secrets to Moscow?
Aldrich Ames
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.
Q 10What did one CIA mole say was the secret of passing the agency's polygraphs?
Confidence and rapport with the examiner
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.
Q 11Why might a person taking a polygraph hide a tack inside one shoe?
To spike the control readings
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.
Q 12In Seinfeld, Jerry is strapped to a police polygraph to hide the fact that he watches which TV show?
Melrose Place
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.
Q 13In England and Wales, polygraph tests became compulsory in 2014 for which group?
Q 21The psychologist who invented the systolic blood pressure deception test later created which comic-book character?
Wonder Woman
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.
Q 22By one family account, who gave William Marston the idea that blood pressure climbs with strong emotion?
His wife
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.
Q 23According to legend, what does Rome's marble Mouth of Truth do to a liar who slips a hand inside it?
Bites it off
High-risk sex offenders on parole
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.
Q 14In which sport do big-money tournaments often make winners pass a polygraph before they can collect the prize?
Fishing
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.
Q 15Which American job applicants are most likely to face a lie-detector test, a practice banned for most private employers?
Police recruits
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.
Q 16Which president said of polygraph tests for his own officials, "I know they'll scare the hell out of people"?
Richard Nixon
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.
Q 17Which president signed the 1988 law that stops most private employers giving workers lie-detector tests?
Ronald Reagan
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.
Q 18Which industries are exempted from the Employee Polygraph Protection Act?
Security firms and pharmaceutical handlers
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.
Q 19Which 1923 court case about an early lie detector set the "general acceptance" test for scientific evidence in American courts?
Frye v. United States
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.
Q 20Which figure in the Kennedy assassination story begged the Warren Commission for a lie-detector test and got one in 1964?
Jack Ruby
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.
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.
Q 24In 1938 Marston fronted adverts claiming lie-detector tests on hundreds of men proved which brand left them less irritable?
Gillette razors
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.
Q 25On whom did William Marston first try his blood-pressure test for lying?
His fellow students
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.
Q 26Which qualification set John Larson, who built the first polygraph in 1921, apart from every other American policeman?
A PhD
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.
Q 27What became of Margaret Taylor, the first student tested when John Larson's polygraph met a real case in 1921?
She married him
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.
Q 28Which nationally renowned Berkeley police chief encouraged Larson's lie-detector work?
August Vollmer
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.
Q 29John E. Reid, a Chicago polygraph examiner, gave his name to a widely taught police method for doing what?
Interrogating suspects
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.
Q 30John Larson came to regret how police used his polygraph, writing late in life that it had become what?
A Frankenstein's monster
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.