Getting your questions ready
Getting your questions ready
Beat the crowd
10 questions No timer
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 01A polygraph records several bodily signals at once. Which of these is one of them?
Skin conductivity
It also tracks pulse, breathing rate and blood pressure while the subject answers questions.
Q 02The polygraph appeared on which reference work's 2003 list of greatest inventions, "for better or worse"?
Encyclopaedia Britannica
Larson's original instrument is now in the Smithsonian.
Q 03What does the scientific community largely consider polygraphy to be?
Pseudoscience
The American Psychological Association says most psychologists agree there is little evidence it can accurately detect lies.
Q 04A 2003 review of polygraph research concluding there was "little basis for the expectation that a polygraph test could have extremely high accuracy" was issued by which body?
National Academy of Sciences
It found 57 of the roughly 80 studies the American Polygraph Association relied on were significantly flawed.
Q 05In a polygraph session, what is the "stim test"?
The subject is told to lie so the examiner can 'catch' it
The idea is to convince guilty subjects that the machine works, though innocent ones may become just as anxious.
Q 06What is the alternative to the Control Question Technique that is used in Japan, testing whether a suspect reacts to details only the perpetrator would know?
Guilty Knowledge Test
Also called the Concealed Information Test, it asks multiple-choice questions such as whether a .45 or a 9 mm was used.
Q 07What is a polygraph test called within the US federal government?
Psychophysiological detection of deception examination
Roughly 70,000 federal job applicants a year were being polygraphed as of 2013.
Q 08In United States v. Scheffer (1998) the Supreme Court said polygraph results were "little better than could be obtained by" what?
The toss of a coin
It left individual jurisdictions to decide whether to admit polygraph evidence at all.
Q 09Which CIA officer turned KGB mole passed polygraphs in 1986 and 1991 while spying for the Soviets?
Aldrich Ames
His handler's advice was to get a good night's sleep, be nice to the examiner and stay calm.
Q 10What did the KGB mole Ames say was the key to beating the polygraph?
Confidence and rapport with the examiner
"There's no special magic," he said; the examiners were later judged "overly friendly".
Q 11A common "specific point" countermeasure is to spike your reaction to control questions by doing what?
Pricking yourself with a hidden sharp object
Thinking of something scary or exciting is the gentler version of the same trick.
Q 12Which country's police were described in 2017 as Europe's most frequent polygraph users, with about 300 tests a year?
Belgium
Its results are used in jury trials there but not accepted as viable evidence in bench trials.
Q 13In England and Wales, polygraph tests became compulsory in 2014 for which group?
High-risk sex offenders on parole
Q 21The 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, complete with a Lasso of Truth.
Q 22Who suggested to William Marston that emotion and blood pressure were linked, noting her own pressure seemed to climb when she got angry?
His wife Elizabeth
Elizabeth Holloway Marston appears in photographs of his 1920s laboratory but was never credited as a collaborator.
Q 23What device does Marston's Amazon superheroine use to force villains to tell the truth?
A magic lasso
Failing cannot be used as evidence, but confessions made during the test can.
Q 14Which Australian state made polygraph evidence inadmissible under the Lie Detectors Act 1983?
New South Wales
The act also bans polygraphs for employment, insurance and lending decisions.
Q 15Roughly how many polygraph tests were estimated to be given each year in the United States in a 2018 Wired report?
2.5 million
Most go to paramedics, police officers, firefighters and state troopers, in a two-billion-dollar industry.
Q 16Which US state admits polygraph testing in jury trials under certain circumstances?
New Mexico
In 2007 polygraph testimony was admissible by stipulation in 19 states.
Q 17The Employee Polygraph Protection Act, which bars most private employers from lie-detector testing, was passed in which year?
1988
Senate testimony said 400,000 workers a year were suffering after being wrongly flunked before the law.
Q 18Which industries are exempted from the Employee Polygraph Protection Act?
Security firms and pharmaceutical handlers
Government agencies at every level are also outside the act.
Q 19The 1923 court case that created the "general acceptance" test for scientific evidence concerned an early lie detector. What was it called?
Frye v. United States
The court refused Marston's systolic blood pressure deception test, and the Frye standard bore its name for 70 years.
Q 20Which 1993 Supreme Court case replaced the Frye standard for scientific evidence in federal courts?
Daubert v. Merrell Dow Pharmaceuticals
Under Daubert the underlying methodology must be scientifically valid, a bar polygraphs struggle to clear.
Her creator styled himself "the father of the polygraph" and lobbied for the machine in courts.
Q 24In 1938 Marston appeared in advertising claiming the lie detector proved which brand's products superior?
Gillette razors
The same year he published his book The Lie Detector Test.
Q 25Marston's early deception research tested his blood-pressure method on which group?
German prisoners of war
The project was abandoned, but he claimed a strong link between systolic pressure and lying.
Q 26Who is credited with inventing the modern polygraph in 1921?
John Augustus Larson
He was a Berkeley medical student and police officer, and the first American cop with an academic doctorate.
Q 27Larson's first criminal use of the polygraph in April 1921 investigated a string of thefts where?
A women's dormitory at Berkeley
He questioned all 90 residents of College Hall, and later married one of them.
Q 28Which nationally renowned Berkeley police chief encouraged Larson's lie-detector work?
August Vollmer
Vollmer later became chief in Los Angeles, and the teenage Keeler followed him there.
Q 29What did the 1920s press nickname Larson's polygraph, because they could not pronounce "sphygmomanometer"?
Sphyggy
His original instrument is now in the Smithsonian Institution.
Q 30Larson came to call his own invention a "Frankenstein's monster" that he had spent how long combating?
Over 40 years
He objected to what he saw as incorrect and abusive use by some police forces.