The typical Hollywood Lie Detector is not like a polygraph. It is instead equipped with red/green lights or a loud buzzing/dinging to indicate truthfulness, which it decides accurately and instantly. The victim is usually betrayed by the machine to comic effect.
While Perp Sweating an especially naive criminal, the cops may employ a fake lie detector, often a photocopier with an ominous paint job. The device really is a photocopier, secretly loaded with pages that have been preprinted with the words "TRUE" and "FALSE". The cops use the machine's answers (sometimes along with a warning that this is a new and experimental model of lie detector that could cause cancer or erectile dysfunction) to coerce the perp into a confession. (Note: some people claim this has happened in real life, but Snopes has its doubts.)
A real life polygraph test typically works by asking you a mixture of embarrassing "control" questions in which everybody is expected to lie (for example "Have you ever lied to a loved one"), and relevant questions ("Did you do it"). If your physiological response on the relevant questions is the same or higher as on the control questions, you are deemed to be lying. Ironically, this means that being perfectly honest makes you more likely to fail the test.
In real life, there is little to no evidence that polygraphs perform better than chance. Interpretation of the results is highly subjective and usually biased by prior suspicions. And even if polygraphs did work, it is trivial to beat them using measures such as biting ones tongue or thinking exciting thoughts to increase responses on the control questions. Most polygraph operators know this; the polygraph is a distraction, and it's the operator who's really watching you.
For almost all cases, real life polygraphs are simply "Unreliable, Unscientific and Biased", according to the National Academy of Sciences, their findings not being admissible in court. So, this is an Inversion of Truth in Television. Despite their proven unreliability, they are still given great weight by both the media and various governments.
Interesting note: The polygraph was invented by William Moulton Marston, who also created the character of Wonder Woman... who happens to wield a magic lasso that forces people to tell her the truth!
Compare with Living Lie Detector, when someone can discern falsehood as a superpower.
- A commercial for Energizer batteries features an Energizer scientist hooked up to a lie detector and the Energizer Bunny in a cage above a tank of piranhas. If the scientist told the truth about whether or not Energizer outlasted Duracell in digital cameras, the Bunny would be safe, and if not, the Bunny would take a dive.
- In one TELUS ad, Danny the TELUS installer is hooked up to a lie detector and asked about Optik TV. The test confirms that Danny is telling the truth about Optik TV.
Operator: Is is true that Optik TV has the most HD channels?
Operator: I've seen you on TV. Do you work out?
Danny: I hit the gym.
Danny: I do!
Operator: Uh huh.
- A commercial for Snapple in the '90s had the writer of a fan letter (in which he states his love of Snapple and says "I am not lying when I say this") brought in for a polygraph test to prove he really was being honest. The machine is realistically depicted as graphing his stress levels with wiggling pens. He passes.
- A Cars.com advert had a couple talking about the lack of drama in buying their car from a Cars.com sponsored dealership. So to make up for it, the dealership hooks up the husband to a polygraph, and tell the wife to ask her husband anything. She then asks if he thinks her sister is prettier than she is, whereupon the husband starts laughing and then rips off the polygraph sensors to avoid answering the question.
- An advert for antiperspirant had a Femme Fatale Spy being tested, but she passed the 'galvanic skin response' thanks to the product.
- Lie detectors in Judge Dredd function on the basis of red and green lights, though they can apparently still be fooled, for instance by messing with the signal. Two spinoffs have shown undercover judges able to beat it. Aimee Nixon is a natural Consummate Liar and, as a result, her tests always give a true result no matter how ridiculous her lies are. Jack Point, on the other hand, has developed a technique where he rewrites the questions mentally so his answers aree technically true and register as such on the birdie. For example, when asked if he has drunk alcohol, he takes it to mean pure alcohol and not whiskey. He notes that it's a pretty exhausting process.
- Superman once encountered an inquisitive college professor who began to suspect that one of his students was Superboy and started asking everyone if they were him as a demonstration for the workings of a lie detector. Superman avoided detection by realizing he was no longer a "boy".
- The 1980's British Starblazer comic had the Truth Meter and the Truth Sensors, but the latter took a long time to work.
- Subverted in Camelot 3000, when King Arthur has each of those suspected of betraying Merlin hold Excalibur while swearing their innocence, saying that the sword can cleave truth from falsehood. The prospect of having to do this makes the culprit break down and confess, after which Arthur admits that he'd made up the claim that his sword can do any such thing.
- In one old Incredible Hulk story, General Ross tried to get Doc Sampson to take a lie detector test regarding his knowledge of the Hulk's whereabouts, forgetting that as a psychologist, Sampson would be perfectly capable of deceiving it. Sampson's response was to threaten to cram it into one of Ross's orifices.
- Dick Tracy had a classic scene where an actual lie detector was used for a great trick in The Blank story. Tracy has a criminal in custody who apparently knows who The Blank is, but he will not cooperate. So, Tracy convinces him to take an optional lie detector test and then asks him to look over some mug shots to indicate which one is The Blank. Sure enough, the criminal demands to be disconnected from the lie detector, only to be told by Tracy that by doing that he just revealed that the real identity of The Blank has a criminal record, a vital clue to work with.
- A recurring theme in Slylock Fox is an apparently infallible lie detector which detects the actual truth of a statement rather than intent to deceive, leaving Slylock (and the reader) to explain how the criminals have used Exact Words to get round it.
- Dungeon Keeper Ami: Ami tried to used her Mercury Computer as one, in "Adamantine":
She paused to focus all of her computer's sensors on the trapped dwarf. She didn't want to miss any sign he was lying when he answered her next question. [...]
The readings on her screen indicated that the padding of the Duke's armour kept him warm under the ice, and there was no shivering to obscure his body's involuntary reactions. There were no indications that he had been less than truthful, either. [...]
this being her first attempt at using her computer as a lie detector[.]
- The LEGO Movie: In a deleted scene, Wyldstyle is captured and wired up to a lie detector. As control questions, she is asked "Is your name Wyldstyle?" and "Do you love Batman?" She says yes to both. Her real name is Lucy, and she is transferring her affections to Emmet.
- Subverted in Equilibrium, which uses a polygraph—not necessarily to detect lies, but to detect emotional fluctuations.
- Used in great comedic effect in Meet the Parents. Already intimidated by Robert De Niro, Ben Stiller was hooked up to the machine. When DeNiro asked, "Have you ever watched a pornographic video?" Stiller visibly stumbled through a "No" while the needles flickered about wildly. He later finds out that Jack Byrnes is a Living Lie Detector, so the polygraph was just a prop.
- The Voigt-Kampf test in Blade Runner - although that is more of an emotion detector.
- Flash Gordon. While Princess Aura is being interrogated by Klytus, she is hooked up to a Lie Detector. When she lies a light blinks and a siren goes off.
- The Adventures of Buckaroo Banzai Across the 8th Dimension. Lord Whorfin hooks Buckaroo up to the Shock Tower, which not only detects when Buckaroo is lying but gives him a shock when he does.
- The Sentinel (2006). Basically the first plot twist. Secret Service Agent Pete Garrison is blamed for treachery and has to go on the run because he failed a polygraph test. Why? Because he was scared they'd find out he's been having an affair with the first lady!
- One character in Anatomy of a Murder has taken a lie detector test, but its results are not admissible in court.
- The movie Sneakers plays this oh-so-straight. The sneakers improvise a lie detector out of an old Cradle Modem and some miscellaneous equipment. They attempt to hand-wave it by saying that it's not as good as a real lie detector because it can only test the stress in the person's voice(Note, that this is through a phone line, and into a device that essentally puts a microphone up to the earpiece), but it still seems to work perfectly and they trust the results implicitly.
- In one of the Ocean's Eleven films, the team nerd has to pass a polygraph test as part of a scam, and spoofs the system by keeping a thumbtack in his shoe and pressing his foot down on it while answering the calibration questions. Later in the same movie, the sophisticated computer systems can tell if a person was cheating at the games by reading various body signals. It is fooled when the rigged slot machine gives off the giant jackpot to a random woman who didn't know about the con. The first example even has the person administering the test point out that, if he didn't have the machine, he would've sworn that Livingston was lying. But the machine passes him.
- Basic Instinct: During Catherine's interrogation at the station, she offers to take a polygraph test, which seems to confirm that she's innocent. Nick counters that she simply manipulated the results, because he knows people who have done it before—not mentioning that he's talking about himself.
- In Freejack, Mick Jagger's character Vacendak suspects a traitor in his team and wants to run everyone through a lie detector. When his Number Two (a longtime friend) starts to walk away, Vacendak tells him to "step up!" The other man puts his hand on the scanner and angrily recites his name, position, and his attitude towards being thought of as a traitor. Vacendak counters that he wasn't testing his friend, he was testing the machine. When the machine gives out the "truth" result, he adds that the machine works.
- The humorous scifi novel Who Goes Here by Bob Shaw had a natural extension of this trope: a Mad Scientist, frustrated with the failings of lie detectors, designed a device to force the subject to tell the truth. It consisted of deodorant to stop him sweating, and devices to keep the subject's breathing and heart rates constant. It failed.
- Appears in David Weber's Off Armageddon Reef as a piece of high-tech gear that looks like a glowing gem the protagonist recognizes but the locals regard as magical, with the color changing to indicate a lie. The protagonist very carefully phrases the answers to not set it off.
- In The Marvellous Land of Oz, Glenda the Good possesses a magical white pearl that turns black in the presence of falsehood, which she uses to extract a confession from the witch Mombi.
- In the Stephen King novel The Waste Lands, Roland and company are on board a high speed train run by a sophisticated A.I. The A.I. informs them it can tell with great accuracy when they are lying by monitoring voice stress patterns.
- The same thing happens in The War Against the Chtorr. During a therapy session Jim McCarthy is told he's lying; he immediately jumps out of the chair he's sitting in. The therapist answers the unspoken question that yes, there are polygraph sensors in the chair, but he can tell Jim is lying from the stress in his voice.
- H. Beam Piper's Little Fuzzy series has the veridicator, which shows blue for truth, red for lies, and mixed patterns for half-truths. The veridicator is an accepted and vital part of the judicial system, to the point that trying to prove that it works on the Fuzzy race is a major plot point in the third book—otherwise they can't legally testify in court.
- The veridicator is also used for an interrogation in Space Viking:
"This is a veridicator. That globe'll light blue; the moment you try to lie to us, it'll turn red. And the moment it turns red, I'm going to hammer your teeth down your throat with the butt of this pistol."
- The veridicator is also used for an interrogation in Space Viking:
- Robert A. Heinlein's novel The Star Beast. A "truth meter" is used on witnesses during a court trial. When the subject lies, a needle swings into the red zone, a ruby light flashes, and a warning buzzer goes off.
- Interestedly enough, a witness is telling all sorts of lies and the device keeps going off. At one time, she tells an obvious falsehood and it doesn't go off. The judge concludes that she really believes what she is saying...even though it patently is false. A limitation of even perfect (i.e. fictional) lie detectors.
- This limitation is also discussed in H. Beam Piper's Fuzzy novels (see above); in-universe, lawyers like to make the point by telling the old saw about the lunatic who said he was God and the veridicator backed him up.
- Interestedly enough, a witness is telling all sorts of lies and the device keeps going off. At one time, she tells an obvious falsehood and it doesn't go off. The judge concludes that she really believes what she is saying...even though it patently is false. A limitation of even perfect (i.e. fictional) lie detectors.
- Also by Heinlein in his Between Planets the protagonist Don Harvey is subject to questioning by Venus Republic soldiers while hooked up to a lie detector after first waiving his rights about self-incrimination.
- In Randall Garrett's story "The Best Policy," an alien race planning an invasion kidnaps a random human and hooks him up to a Lie Detector in order to get information. He manages to cleverly word his answers so as to give them the impression that humanity is insanely powerful and not to be messed with.
- In On a Pale Horse, Luna and Zane hold Truthstones (which glow when someone lies) while discussing sensitive personal matters.
- Kurt Vonnegut's novel Player Piano includes a courtroom scene where the protagonist is hooked up to a lie detector with a large dial ranging from "False" to "True".
- The Goblin Wood by Hilari Bell features an explicitly magical version of this; a bell that rings when a lie is told near it. This has its downsides, as indicated when its user is asked, "Are you sure this will work?" "Of course I'm sure—" Ding. Later, her captive turns the questions around on her, and in response to her Motive Rant asks whether her Actual Pacifist mother would appreciate the violent vengeance that has been taken for her murder. "If my mother was still alive, she'd be proud of me!" Ding.
- In Life, the Universe and Everything, a witness is forced to tell the "whole truth" after being given too much truth serum. Sure enough, he begins spouting facts about everything the universe has to offer. It takes him several years.
- The Heralds of Valdemar series has the Truth Spell, the only form of magic known to the Heralds between the death of Vanyel and Elspeth's becoming a Herald-Mage centuries later. The spell has two forms: The weaker form is a truth/lie indicator, the stronger form forces the target to tell the truth as they know it.
- The Magic and Malice duology had a truth spell connected with a set of artifacts known as the Saltash Set. The spell used with the full set can compel a person to tell the truth. With an incomplete set of the artifacts, it just indicates whether the person is telling a lie or the truth (or if they're hiding part of the truth).
- A truth spell is used in Simon R. Green's Hawk & Fisher, which forces people to speak only truthful statements. This attempt to find out who committed two murders fails, due to the murders having been committed by two different people, each of whom could truthfully deny having killed both victims.
- In Snow Crash by Neal Stephenson the rump of the federal government (which pretends to still rule the USA) has its employees take weekly lie detector tests that may involve sedative drugs and NMR machines to detect activity in parts of the brain used for lying. It's a plausible technology for a reliable lie detector.
- In William Brittain's story "The Artificial Liar," one of the guards at a government research center was gaslighting a file clerk who lived in the same boardinghouse as him so that, during the inevitable investigation after said guard had smuggled out some highly sensitive material, his chosen patsy would have extreme reactions to the polygraph questions.
- The Katharine Kerr novel Snare has shamans who can smell whether or not a person is telling the truth. It works by detecting a person's emotional state through subtle changes in a person's scent (One of the talents held by the shamans is exceptionally sharp senses), and lying makes most people nervous. It's mentioned that this might not work against a habitual liar who would remain perfectly calm when deceiving others.
- In Mercedes Lackey's Firebird, Ilya suspects Mother Galina may be one (he's certainly never been able to lie to her), and fears the Katschei might be one. His experience in getting around the former helps him considerably with the latter.
- The Stainless Steel Rat beats being polygraphed by the secret police on a couple of occasions, once by working himself into an artificial state of panic before the test, then thinking boring thoughts during it. In another book he insists on a lie detector and is told the chair he's sitting in is one, causing him to think, "I'm glad I didn't know that when telling those other lies!" The Rat then proceeds to give a truthful but misleading statement that clears him.
- In the first novel the Rat breaks into the home of a politician and finds some handy blackmail material about numerous corrupt deals. The politician claims everything he's found is a Frame-Up, whereupon the Rat reveals that the security robot holding the politician captive is also a lie detector. The robot confirms that 74% of everything the politician has just said is a lie...except about the case the Rat is investigating. Their conversation then proceeds on a more amiable basis.
- Parodied in Diary of a Wimpy Kid: Cabin Fever when the school is vandalized. The police come there to question the worst troublemakers, but it's obvious that their "foolproof lie detector" is just a photocopier. Whenever the troublemaker says something they don't like, they hit a button to copy a sheet that says "He's lying". Predictably, they fail to catch the real culprits.
- Subverted as early as 1913, in the Father Brown story "The Mistake of the Machine". Father Brown is introduced to a Psychometric Machine that measures the suspect's pulse, and is rather scathing of the idea, saying American scientists must be great sentimentalists to try and prove things from heart-throbs. He proves his point when a man is accused of murder based on his pulse rate when the victim's name is mentioned, and Father Brown is able to demonstrate another reason for this.
Greywood Usher: Now, in my opinion, that machine can't lie.Father Brown: No machine can lie. Nor can it tell the truth.
- In The Lost Fleet, interrogation rooms are actually brain scanners similar to an fMRI. The machine shows the interrogator when regions of the subject's brain associated with deception or various other emotions light up, so not only do they know when the subject lies, but they can also tell when one of their questions has really hit home, even if the subject is refusing to answer at all. There are ways to deceive without setting off the machine, but those usually involve Weasel Words that a skilled interrogator can spot. Of course, the machine can still only tell you what the subject believes, so false answers with no deception noted are still possible from a dupe or a delusional subject.
- In Earthsearch by James Follett (also a Radio Drama), the Chief Prosecutor of the Solaric Empire interrogates Astra with two cerebral analysers focused on her brain. Lying modulates the beams causing a feedback "that you are unlikely to survive." So when Astra says that the spaceship she's from is unarmed and stranded in orbit around another planet, the Prosecutor thinks it's safe to kill the prisoners. Astra isn't lying; she just doesn't know that the asteroid Deflector Shields make a handy Improvised Weapon and the surgical androids can be reprogrammed to pilot the spaceship, which arrives Just in Time for a Big Damn Heroes.
- The Drew Carey Show:
Mr. Wick: "Carey, you're one of our most valued employees." [buzz] "Well, maybe not, but I respect you a lot." [buzz] "You've got a bright future here..." [buzz] "Oh, will you get these things off me! I don't like being tied down like this!" [buzz]
- Family Matters: Steve's lie detector has the added feature of giving Carl an electric shock if he doesn't tell the truth. After Carl and Steve work out the issue they were having, Harriet decides to take the opportunity to ask Carl how many women he was serious about before her, resulting in him being continuously shocked.
- Murphy Brown: Murphy takes a buzzing lie detector test after she accuses a coworker of sexual harassment. Miles takes the opportunity to get Murphy to confess having switched his medical records with a guy from Accounting as a prank, causing the former to get an enema and the latter to get unnecessary stomach ulcer surgery.
- An episode of Nikita has Alex hooked up to a "FMRI" it looks alot more like an ECG and is able to trick it through short and precise statements that are technically true. The problem is that to make such statements avoiding a lie would cause a lot more activity in the brain than such short statements would produce normally.
- Stargate SG-1:
- A strange alien lie-detector appears on several episodes, which is somehow capable not only of discerning when the person is telling a lie, but also when they're lying even if their conscious mind thinks they're telling the truth. However, the Za'tarc detector only detects concealment, not the subject being concealed. This distinction becomes important when Jack and Sam come under suspicion because they trigger the Za'tarc detector. It's not because they've been compromised, but because they're trying to conceal that they care about each other "way more than they should". The operating principle of the Za'tarc detector assumes that (as was once widely believed in real life, but now has fairly little support) the human mind secretly keeps an accurate "recording" of everything it experiences, and therefore even an unknowing lie (and even, one supposes, an honest mistake) can be detected by comparing what is said to the infallible mental record. The device is related to the Mental Picture Projector technology sometimes seen in the series.
- Also, the comedic take was subverted in an early season 10 episode with an ordinary lie detector, where the tester is tortured:
Tester: By the way, I must say you're looking excellent today.
Vala: Thanks, you look excellent yourself... [needle ticks rapidly] I mean, very nice... [needle ticks rapidly] That is, not objectionable... [needle ticks rapidly]...
- Gilligan's Island: The Professor builds a lie detector out of — what else? — bamboo and coconuts and tests all the men to find out who sent Mrs. Howell a love letter. One of the gags is The Skipper passing until he says, "See? I always tell the truth," which sets it off. At the end of the episode, Gilligan is playing with it when Mary Ann comes in asking him what happened to a couple of coconut cream pies she made, and Gilligan denies seeing or taking them, which causes the lie detector to explode.
Gilligan: Well, they were delicious.
- Avoided in Alias, which features a more realistic lie detector—that is to say one that doesn't explicitly say "Truth" or "Lie", but just provides raw data such as heart rate and blood flow in particular areas of the brain, requiring the interrogator to use his own judgment to decide on the truth of a given statement, and being much harder to fool. Then, outright subverted, when the difficulty of tricking the device almost gives away the protagonist, when after extensive training and practice with her handler her results look too perfectly honest during the real interrogation.
- In the Jonathan Creek episode "The Tailor's Dummy", TV presenter Carla, who is preparing to host a talk show with a lie detector as the gimmick, uses it to prove to Jonathan she's happy in her marriage with the show's director. It announces she's lying. Later the director (who doesn't know about this) admits to Jonathan that it's completely random.
- The X-Files episode "Squeeze" uses a lie detector test to good effect, where the killer manages to fake his way out of the test quite effectively - except for two questions Mulder inserted implying the truth about his identity (that he was over one hundred years old and a human liver-eating mutant) that he most definitely was not expecting, which pinpoint the fact that he is lying. Of course, the other agents aren't willing to accept that he's one hundred years old and let him go anyway. As the other agent points out, any innocent man would likely have had some kind of reaction to that question. Mulder might have had a better result if he'd asked Tooms about the victims he killed decades ago, using their names but giving no other details.
- In Seinfeld, Jerry takes a surprisingly realistic lie detector test to try and prove he doesn't watch Melrose Place. Instead of being asked directly, he's just asked to give his details before being asked a string of questions about events from Melrose Place ("Did Kimberley steal Jo's baby?" "Did Billy sleep with Allison's best friend?" etc etc). And instead of lights or buzzers or wildly jagged needles, the needles just jiggle a little when he answers, but not in any significant way. In the end he breaks down under the pressure of endless Melrose Place trivia and confesses, and we never find out whether he was beating the machine or not.
- From back in da day, the lie detector was the plot point of an episode of Barney Miller, as an entire police division was being randomly tested (a procedure that was the Hot Topic of the Day in the 1970s). Det. Wojohowicz failed miserably due to being nervous and deliberately provoked, while Det. Dietrich passed perfectly (despite claiming to be from outer space) simply by remaining calm.
- In Star Trek: The Original Series, the Enterprise's computer has a lie detector function seen in a few episodes.
- In "Mudd's Women", it states that Mudd's responses are "INCORRECT" when he gives a false name, claims he has no criminal record, and states that he is licensed to operate a spaceship. It's possible that the computer identified Mudd's face and then compared his statements to records, as it immediately provides the true answers.
- In the episode "Wolf In the Fold", it gives the response SUBJECT IS RELAYING ACCURATE ACCOUNT when questioning serial killer suspects.
- Star Trek: Voyager. In "Ex Post Facto", Tuvok uses an Autonomic Response Analysis to interrogate Tom Paris. It shows that he's telling the truth about not committing the murder he's accused of, which turns out to be a Frame-Up. However in "Basics, Part One", Chakotay requests the Doctor do an ARA to see if an alien prisoner is lying. The Doctor points out that they don't have enough baseline information on that species to give an accurate result.
- The sheriffs on Reno 911! frequently spend their downtime interrogating each other with the polygraph. Of course, the questions or responses invariably turn uncomfortably personal, and Hilarity Ensues.
- Parodied in this sketch on Mr. Show; prospective employers are interviewing a job applicant and putting him through a lie detector test. It starts with basic questions (like "Have you ever drank alcohol to excess?" or "Have you ever taken an illegal drug?"), but they're soon flummoxed when the applicant - who answers everything in the affirmative - begins confessing to the most ludicrous things, including being addicted to every hard drug known to man, stealing 'space plans' from NASA, killing a man with his mind, and eating a train piece by piece after first derailing it with his penis (for charity). All the while, the lie detector is silent, indicating that he is telling nothing but the truth. Eventually, the employers - who are revealed to be the operators of a shoe store - give him a job, and the applicant says that he loves shoes - BUZZZT!
- In the short-lived sitcom Quintuplets, two of the brothers, Pearce and Parker, try to make a lie detector in order to find out which of the two their mutual crush likes better. Unlike most detectors, when someone lies, the detector makes toast. Pearce is the one to put the thing together, and tests it out on himself. He sets it up, and tells Parker to touch it. The detector gives Parker a (very painful) shock. Pearce tells Parker, "I had no idea that was going to happen." Toast pops out, leading Pearce to gleefully exclaim "It works!" Hilarity (and disaster) ensues.
- There's one beneath the Buy More in Chuck, which they use to question a character about Fulcrum activities. Too bad Chuck didn't pay attention to the last answer...
- Lie to Me:
- The show, which bases its detection off people's microexpressions, hates polygraphs. The characters point out that your reaction is going to be altered if say, a hot chick walks in and takes over the lie detector exam. Also that you might as well use a large egg being held in your hands as one, because if you are under stress and squeeze and break it, that could indicate that you're lying. In one episode, they show it's possible to beat a polygraph by taking a depressant to decrease your body's stress reaction. The main character can make utter hash out of not just polygraphs, but his own system - in the pilot episode, he tests a recruit by faking stress.
- In a later episode, they use a (fake) polygraph on a suspect who he knows is going to try to trick the system. The idea is that he'll focus on trying to trick the polygraph instead of the people reading his facial cues.
- Used twice by Homicide: Life on the Street.
"We're gonna neutron this son-of-a-bitch!"
- Parodied in at least one case; the 'lie detector' turns out to be a photocopier that the detectives have loaded with sheets of paper with "LIE!" printed on them, which they use to trick particularly credulous suspects into confessing the truth.
- The fifth season premiere of The Wire opens with Bunk Moreland and a bunch of other detectives using the above-mentioned photocopier trick to trip up a suspect.
- Repeatedly on all versions of Law & Order.
- The show frequently alludes to its fallability and inadmissibility in court, at least.
- As always, MacGyver (1985) did it. As always, it worked well enough to cause the villain of the week to give himself away. Notable components included an alarm clock and a sphygmomanometer.
- Used in The Unusuals against a serial killer of cats. It appeared to be a Lexmark or Canon inkjet printer with the lid over the scan plate removed.
- RoboCop: The Series:
- Robocop was literally a walking lie detector. He used "voice stress analysis" to make instant, near-infallible truth assessments. However, it was very plot-sensitive; Robo could easily use it to interrogate low-level criminals and witnesses, but the real bad guys always had some way to beat it.
- A recurring nemesis was able to make the system give null responses because he was a stone-cold sociopath.
- Once they had to interrogate a career politician, which just plain broke the system. He was such an instinctive liar that every statement he made registered exactly halfway between truth and falsehood. He was able to make the system give a null response to a claim that he was Abraham Lincoln. He walks out because a female acquaintance (not his wife) explains that they were together at the time of the crime. The machine works this time.
- In the Torchwood episode "Adam", Jack uses the "best lie detector on the planet" (complete with green/red light) on Ianto, who has had false memories implanted. Since Ianto is convinced he's murdered 3 girls, no lie is detected ... but Jack still knows he's innocent.
- The Commish. The title character knows that an informant is somehow beating the lie detector, and uses a Honey Trap to find out how. It turns out he's placed a thumbtack in his shoe, and is pressing down on it so as to give the same response each time. The Commish schedules another test, then has him walk up and down an endless amount of stairs under the excuse that the testing area keeps getting changed. Eventually the informant realises the game is up and removes the tack to give his by-now extremely sore foot a rest.
- Battlestar Galactica. In a flashback to before the war, Adama is seen applying for a job in which he must take a lie detector test. One of the baseline questions (used to establish the reliability of the other questions) is "Are you a Cylon?" (This was before anyone knew the human-looking Cylons existed). In a further irony, the man administering the test is himself a human-cylon.
- The Parkers: A lie detector watch zaps when the wearer tells a lie.
- seaQuest DSV has a police officer in one episode with a sneaky lie detector. He hands people a roughly pen shaped object, tells them it was found at the scene and asks if they have any idea what it could be. After they answer in the negative he proceeds to ask regular questions. The device is actually a lie detector which he owns and he is tricking them into holding it while being questioned.
- The first episode of Lois & Clark has a polygraph that works this way. Clark's 'baseline' questions are 'Is your name Clark Kent' and 'Are you Superman'; he's supposed to say yes to both and get a 'lie' response on the second, and even though he's totally freaked out at saying it to the Superman-hunters, saying 'yes' he's Superman gets a no-lie flatline. The hunters mutter "the machine is broken or this reporter is so mild-mannered he hasn't got a pulse," to make things more confusing, and funny. He sets it off by blowing on the needle with super-breath to get his no, then sets it off by saying he can't contact Superman. (Although it's fine with 'I've never met Superman.') Magic! On another question where he needs to set it off, he levitates an inch above the floor and drop the chair, setting off the needles.
- This old Johnny Carson skit on The Tonight Show involves a politician who agrees to be hooked up to one of these at a press conference, with the expected hilarity ensuing.
"I feel my opponent is a decent man." [BUZZ!] "He's an okay man." [BUZZ!] "He's a man." [BUZZ!] "He's bisexual."
- An episode of Tek War had a hardline investigation unit use a combination lie detector/shock collar - Hand Waved as a neural interface which detects "cognitive dissonance" instead of just reading biorythyms, and turns said dissonance into direct stimulation of the pain center. It's used once on a known criminal, who gives truthful information after realizing his training(Truth in Television) can't beat the device. However, the designers never accounted for someone absolutely determined to defy the device; it's later used on a hotel maid that they suspected was concealing evidence. The Mob Boss Is Scarier, she hated the cops, so she denied knowledge despite increasing levels of pain until it rendered her comatose.
- In Pan Am Kate has to pass a lie detector test that she has to lie to in order to not incriminate herself regarding a man she shot.
- In Psych, Lassiter uses one on Shawn with excuse that he's just testing whether the machine is working or not to figure out whether Shawn's secretly dating Juliet. The machine appears at first to be a typical hyper-accurate bit of Hollywood Science (registering an honest response when Shawn blurts out that he's in love with Juliet while hooked up to it), but promptly subverted when Lassiter follows up with the question "are you psychic?". Shawn lies and still passes the test. A flashback at the end of the episode reveals that learning how to beat a lie detector was one of the many skills Henry taught Shawn as a young boy (namely, trying to believe in the lie so that the polygraph registers an honest response).
- At the end of the episode, Lassiter invites Shawn into the interrogation room and hooks himself up to the machine. He then proceeds to tell Shawn that if he ever hurts Juliet in any way, he will discharge his pistol. Repeatedly. The result? Zero deception.
- On Roseanne, the employees of Rodbell's have to take a lie detector test. During the end credits, manager Leon is asked about Roseanne and the machine explodes when he lies and says he thinks she's a good worker.
Polygraph Tester: Do you consider Roseanne a good worker?Leon: Well... I... I guess... she has her—Polygraph Tester: Yes, or no, Mr. Carp.Leon: Well... okay then... (nervous pause) Yes. (The Polygraph explodes, sending sparks everywhere) ...I knew that was going to happen.
- Hot Seat was a short-lived ABC game show from 1976 (premiering the same day Family Feud did except it aired at the low-clearance 12 noon spot) that had couples being asked questions about their married life while attached to a lie detector.
- Talk shows like Maury and Jerry Springer use this all the time, often to find out whether a spouse or significant other is unfaithful or for other purposes. So much so that the use on Maury has now become a meme!
"You said that [Statement]. [Contradiction] determined that was a lie".
- Also used in Great Britain by Jeremy Kyle on his lowest-common-denominator confrontation show and treated as if it had God-like infallibility.
- In the Smallville episode "Committed", a psycho named Macy would kidnap couples and hook them up to these, then question them about their love lives and fidelity. For each lie, the other person gets electrocuted. When Macy mistakes Lois and Clark for a couple and kidnaps them (thanks to kryptonite), Lois answers "Yes" when she's asked if she loves Clark, which registers as the truth much to Clark's shock as the pair couldn't stand each other at this time. Later, after they are freed, Lois claims that she slipped the sensor off her when she gave her answer.
- In the Murdoch Mysteries episodes "Still Waters" and "Invention Convention", Murdoch has a device of his own invention called a pneumograph, which as the name suggests, measures the suspect's breathing. Instead of the lights, his machine has blue liquid that rises in a spiral-shaped tube. Despite not having any of the other measurements of a polygraph, it appears to be nearly infallible... providing Murdoch is asking the right questions. Murdoch himself is the subject when he first demonstrates it for his colleagues, a demonstration very much Played for Laughs. Of course Dr. Ogden walks in, and the questions get very personal, and Murdoch is embarrassed by the accuracy of his own invention.
- In White Collar:
- In season 2, episode 6, Neal confounds a polygraph by pressing a tack into his finger during sensitive questions.
- Later, in season 3 (ep 1), a polygraph is used on Neal who tells the truth, but his questioner is still not convinced.
- On ER, after Doug tells him he has reconciled with Carol, best friend Mark teasingly asks him if she makes him submit to this as a condition (Doug cheated on her left and right the first time they dated).
- In The Americans, Stan tells Nina that she will have to pass the lie detector in order to be exfiltrated, thinking Nina was sincere with him. As Nina was a double agent she was trained by Oleg for passing the test. She did.
- An episode of The Good Wife revolves around the idea that NSA employees are regularly given lie detector tests. The results are never depicted (including when a character answers a question regarding removal of classified files from the office while unsure if he technically did so), and it's implied that the tests are more about presenting questions intended to manipulate people into revealing their own mistakes or wrongdoings.
- The use of a lie detector was actually Played for Drama in an episode of The Jeffersons where Lionel was offered a high paying job. At his interview, after answering all questions given to him, he was obligated to answer them again while hooked up to a lie detector. Feeling he was being denied his rights, he turned the job down, much to George's anger.
- In the episode "Dream a Little Dream," Chiana and Rygel must defend Zhaan against a murder charge on Litigara, a planet where 90% of the population are lawyers. One of the cornerstones of their legal system is the (generally considered to be metaphorical) "Light of Truth," which blazes brighter in the presence of lies. Chiana lights a broken chair leg on fire to serve as the Light of Truth when accusing a prominent lawyer of framing Zhaan. The accusation is true, but Pilot is manipulating the stick from orbit.
- Another episode has a straighter example in the form of an alien headcrab monster that was trained by the local merchant guild to sit on people's heads and stab through their skulls if they told a lie. It requires incredible force of will to fool, and Crichton would have been killed by it if not for the fact that he had access to an identical twin for whom the statements he had to say were indeed true. The villain of the episode managed to deny all of his crimes with much effort, but couldn't successfully say a false answer to a big question that Crichton asked completely by accident: "Well, aren't you just a good and loyal son?"
- Person of Interest:
- In "Booked Solid", Detective Carter is polygraphed for her application for the FBI, and worries that it will expose her association with Team Machine. Finch advises her to lie on an early question to skew the results. So Carter confesses to having smoked marijuana in college, and the polygraph operator congratulates her on being the first one to answer that question honestly.
- In "Proteus", Finch rigs up an improvised version with seismograph equipment, measuring the micro-tremors from the interviewees hands as they rest on the table.
- In Wiseguy Frank McPike says he Experimented in College with marijuana. When Vinnie asks how he passed the polygraph when applying for the FBI, Frank says he didn't consider himself a user.
- House once used a Cat scan as a lie detector, observing which parts of the patient's brain were active to tell when he was lying.
- Penn & Teller: Bullshit! has an episode on polygraphs and their operators. Their case study, a private contractor, uses the machine as his Bad Cop in a Good Cop/Bad Cop routine (despite not actually being a police officer or affiliate).
- An episode of Adam Ruins Everything has Adam debunk the usefulness of a polygraph, pointing out that even the machine's creator was horrified when he learned that cops were using it to seriously question suspects. Hell, the polygraph was once used to tell that a plant was lying. The cops then admit that they know it doesn't work, but they use it to Perp Sweat ignorant suspects. Of course, the whole thing is an Engineered Public Confession to the audience.
- An episode of Sliders has the heroes find themselves in a world where the US is under a martial law, the Constitution has been banned, and all cops wear skirts. When Rembrandt goes to the police to trade the last known electronic copy of the Constitution for the freedom of a judge (one of the last "Constitutionalists"), the chief asks if he's willing to take a lie detector test to prove that they haven't made any copies of the disk. Rembrandt agrees, although the actual test is not shown. At the end of the episode, a copy of the document is emailed to everyone.
- One episode of World's Dumbest... features a gadget called the "liar card" which acts like a phone version of a polygraph, telling you if the person you're talking to is lying. Of course, it also gives you the ability to lie to the other person with a fake phone number and/or a fake voice (which sounds like the classic "ransom demand" voice, for whatever reason); several commentators point out how morally gray this is.
- The British sketch comedy series The Russ Abbott Show had a sketch where the police tries to use a new kind of lie detector, which notices the lies by testing the voice and the suspect doesn't have to be attached to it. The interrogator ends up embarrassing himself when the machine buzzes at his lies ("I'm a very busy man!" "I am not a man to use violence!" "I can't be bought!")
- The Good Place: Michael uses a cube which flashes green when someone tells the truth and red when they lie when investigating Eleanor.
- In the live-action drama adaptation of Death Note, L uses a polygraph on Light. He does not do so in the anime or manga.
- Blake's 7.
Caliph: The neuronic whip is on an automatic setting. It has only to sense one lie and it will boil your brains in your skull. Where is Orac?Tarrant: If he's not on the ship, I don't know where he is.Caliph: How tall is he? (Tarrant demonstrates) A dwarf?Tarrant: We never think of him as one.Caliph: What is the color of his hair?Tarrant: He hasn't got any. A bald dwarf shouldn't be too hard to find.
- In "Dawn of the Gods", our heroes are able to beat this through Exact Words. The Caliph is seeking Orac, not realising it's actually a Master Computer.
- The pilot episode shows that this trope doesn't work on someone who's been brainwashed to believe their own lies. Blake is framed for molesting children, and it's mentioned the accusers have all passed a lie detector test. However he's been framed by the government so they Don't Create a Martyr, and his lawyer discovers the children have all been taken out of school for unregistered medical treatment on the days they said they were assaulted.
- Vila insists that Master Computer Orac verify an offer of Servalan's is genuine, apparently because Computers Are Just Better at detecting these things. This is suggested in an earlier episode where a Rebel Leader has been replaced by a Federation robot and kills a rebel who's become suspicious, because it would be able to pick up his body language showing that suspicion no matter how he tried to hide it.
- In 2003, Vince McMahon suspected that Mr. America was Hulk Hogan in disguise (he was) and forced him to take a lie detector test. Mr. American passed when he said he wasn't Hogan. Angry, Vince took the test to prove it was rigged, only for the machine to buzz when he said things like he wasn't an asshole, wasn't a pervert, etc.
- Subverted in GURPS: High-tech even if the polygraph works as advertised (by default it doesn't) the machine still doesn't detect lies, the interrogator is the one doing that. By Ultra-Tech lie detectors that operate on micro-expressions and brainwaves have been perfected.
- There's a short adventure from an early Dungeon magazine, in which an elf suspected of murder steals a magical lie-detecting sword and flees before it can be used in his trial. He's innocent, but knew that the sword also detected elves, and was afraid its use to test his statements would ensure his wrongful conviction.
- The core rulebook for the "XP" version of Paranoia includes a picture of an Alpha Complex citizen strapped into one of these. He's grinning and giving a thumb's-up, while behind him an enormous video screen blares the word LIE.
- The Kanohi Rode, Mask of Truth, in BIONICLE essentially does this: it can see through any deception or illusion, but as far as lies go, it seems that it can only tell if the potential liar truly believes what he is saying or not.
- The Magatama in the Phoenix Wright: Ace Attorney series sort of works like this. Whenever Phoenix encounters a person that is either lying or is hiding a secret, the Magatama shows chains and locks over the person in question. The more locks there are, the harder it is to crack the person into spilling the beans. In one notable case, this system is fooled by Phoenix's own client, who actually is the killer for once. He had the victim taken out by a hired killer, so when asked "did you kill him", he just says "no". Normally the Magatama sees through Exact Words of that sort by detecting the associated guilt, but it's implied that he's The Sociopath to the point that he didn't have any guilt over it.
- In The Sims 2 a lie detector can be unlocked as a career reward item for the criminal track, although in this case, the use for it is not to tell when someone is lying, but to increase a Sim's creativity skill by learning how to lie without setting it off (it will give the Sim an electrical shock if they fail).
- NSFW Comix had an Independence Day comic where two fast food workers are interviewed by the secret service about the "secret ingredient" they added to President Obama's burger using a typical Hollywood Lie Detector.
- Electric Wonderland has Aerynn cast a spell that causes one's pants to light on fire if he tells any lies.
- Reynard Noir. Slylock simply tricks the perps into thinking it's caught them lying by raising their stress levels.
- In Worm, Armsmaster creates a lie detector that actually works. It's later used by Legend as well.
- Grandmaster in Enter The Farside can have his helmet customised to include one of these. It can also pick on responses and relay back their tells and ticks. In Beginnings 2-3, Shaun believes Artifex used one of these on him.
- SCP Foundation: SCP-2128 is a stone furnace used as a torture device by a medieval cult. Whenever someone in the oven tells a lie, the SCP incinerates them. This happens even for things the person doesn't know the truth of, and it has ways of avoiding paradoxes. It's sentient, loves to eat human flesh, and isn't above roasting a truthful person.
- In the lonelygirl15 episode "Man in the Suit", Bree tries out a "home-made lie-detector", i.e. a piece of paper and a pen, on Daniel. He has to draw a straight line on the paper while answering a question; supposedly, if the line wobbles, he's lying. In which case he is, or has in the past been, a member of a terrorist organisation, and he intends to eat P. Monkey, Thor and Owen if he runs out of food.
- The Simpsons:
- Parodied when Moe was interrogated by the local police force.
Tester: It checks out. Okay, sir, you're free to go.
Moe: Good, 'cause I got a hot date tonight. [buzz] A date. [buzz] Dinner with friends. [buzz] Dinner alone. [buzz] Watching TV alone. [buzz] Alright! I'm gonna sit at home and ogle the ladies in the Victoria's Secret catalog. [buzz] ...Sears catalog. [ding] Now would you unhook this already please? I don't deserve this kind of shampy treatment! [buzz]
- In "The Springfield Files" (Fake Crossover with The X-Files), Agent Scully hooks Homer up to a lie detector and explains how it works. When she asks him if he understands what she's told him, Homer says yes and the machine explodes.
- In "Poppa's Got A Brand New Badge", Bart tries out a lie detector, saying "Lisa is a dork!" over and over. Naturally, Lisa doesn't like that, but when Homer looks at the sheet, he says "According to this, he's telling the truth.".
- Parodied when Moe was interrogated by the local police force.
- Batman got hooked up to one in The Batman. If he lied, though, Detective Ellen Yin got shocked. The Riddler did this to play a Twenty Questions game with Batman. The Riddler wanted to ask Batman 20 questions and use the answers to deduce Batman's identity. When Batman lured Riddler into a position where he would feel the shock, Batman answered 'Yes' to Riddler's question about Batman being a cop.
- The Three Little Pigs Disney short "The Practical Pig" (1939) features a lie detector, which notably goes off on Practical when, while punishing his brothers, he proclaims "This hurts me more than it hurts you!"
- Beavis and Butt-Head were forced to take a lie detector test after being suspected of taking money from the Burger World cash register. Before they took the test, Butt-Head told Beavis that they can trick the lie detector by holding their breath. When Butt-Head steps up, the lie detector buzzes when he claims that he understands how the lie detector works but dings when he gets the number of fingers the man holds up wrong; when asked if he ever stole anything in his life, he passed out before he could answer. When it was Beavis's turn, he successfully convinced them that he was a serial killer from the 1960s, and he didn't even hold his breath yet.
- In the Futurama episode "A Head in the Polls", Nixon's head is put under a "truth-o-scope" during the presidential debate. Cue flop sweat when he's asked whether he'd take candy from a small child.
Nixon's Head: Uhh... well, the question is vague. You don't say what kind of candy, or... whether anyone is watching... In any case, I certainly wouldn't harm the child. [truth-o-scope goes nuts]
- In one of the episodes of The Fairly OddParents!, Timmy's parents suspect him of stealing and he whips up a Lie Detector. Which works against him of course. Timmy's Dad asked where he got the detector and Timmy, out of habit, says "Internet".
- Ed, Edd n Eddy strap Jonny 2x4 to one of these in the Pilot Episode when they suspect him of stealing possessions from the children of the cul-de-sac.
- Every time The Powerpuff Girls tell a lie in "Lying Around The House," a mysterious little figure starts to grow until it becomes unmanageably monstrous. The girls can only defeat it by renouncing their lies and telling the truth. First implemented in issue #21 of the comic book ("Big Fish Story," DC run) in which the little fish the Professor caught grows with the girls' lies as it is manipulated by Him.
- One episode of Pacific Heat has a witness being subjected to a voice stress test, with Kwong measuring her vocal stress via sensors and determining whether or not the witness is lying. Of course, the sensors also track the voices of the Pacific Heat agents, and Kwong has fun announcing when they're lying.
- Batman: Assault on Arkham. Harley Quinn tells Batman she doesn't know where the Joker has hidden a dirty bomb. The eyes on Batman's mask light up and we see a scan of her physiology (heart-rate, pupil dilation, etc) which reads as normal to establish that she's telling the truth. Which raises some Fridge Logic she had just fought Batman hand-to-hand, so why would her heart-rate be steady?
- The first episode of The Crumpets has Ma building one and having her family tested so she can find out who kidnapped her husband.
- In the Rick and Morty episode "The ABCs of Beth", one item that Rick invented for Beth in her youth was a doll that very blatantly had a lie detector built in.
- Various people with U.S. security clearance have taken polygraph tests and passed, despite being foreign spies. From 1945 to the present, at least six Americans had been committing espionage while they successfully passed polygraph tests. Two of the most notable cases of two men who created a false negative result with the polygraphs were Larry Wu-Tai Chin and Aldrich Ames. Ames was given two polygraph examinations while with the CIA, the first in 1986 and the second in 1991. The CIA reported that he passed both examinations after experiencing initial indications of deception.
- The NAS report that led to the downfall of the device's widespread use pointed out that they said this about pretty much everyone they ever "passed".
- Magnetic resonance imaging scans can pinpoint which parts of a person's brain become more active when they engage in particular types of thinking, and making up a lie on the spot causes different areas to "light up" than relating things from one's memory. Note that this is only true of lies being invented at the time the test is being administered; a long-term deception still in progress, or a lie that's been thoroughly planned out in advance, may produce a similar pattern of activity to a genuine recalled memory.
- In 1993, then-President Bill Clinton called up KMOX in St. Louis (1120 AM) and said on-air, "After I get off the phone with you, Rush Limbaugh will come on and have three hours to say whatever he wants and I won't be able to defend myself. There's no truth detector." Limbaugh came on shortly after and said, "We don't need a truth detector. I am the truth detector."
- After Susan Smith claimed her children had been kidnapped by a carjacker, she and her estranged husband David were submitted to this almost immediately. David passed with flying colors and was never tested again, while the results of Susan's exam were inconclusive and she was tested everytime she was interrogated. She repeatedly failed the question, "Do you know where your children are?" After nine days of this, she finally broke down and admitted that she had killed her children.