Do Lie Detectors Actually Work? | Earth Science

You might see lie detectors on television shows, but do they actually work? Can a machine tell if you're lying? Greg Foot explains how lie detectors work.
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[@maskimgalgo2046]

Imagine being framed for murder because a machine basically goes: " i feel like he is lying"

[@thedarknessunderneathpodca6366]

Google Jeffrey Deskovic in wiki. He wasn't framed exactly but the cops, based on no evidence, said, hey, she knew a weird kid, let's pin it on him., and had nothing but false hunches. He then took one much later and failed even though he was innocent. DNA 16 years later found the real suspect after he spent all that time in prison.

[@lans2636]

@@thedarknessunderneathpodca6366 I have heard some cases like this and specially when the people are black the US just put them in jail without evidence, I truly hope those people who lost half of thier lifes unfairly live happily ever after.

[@thedarknessunderneathpodca6366]

@@lans2636 lie detector tests aren't really admissable as evidence. They use them as part of interrogation to get confessions but it can cause false confessions, esp in kids, if the cops promise they will not punish you as much if you say what they want.

[@ADSR.682]

Machines doesn't have feelings

[@RandmAnimal]

@@ADSR.682 is a joke

[@GodPikachu]

"How do lie detectors work?".....Answer - they don't

[@iwasadeum]

Exactly. They work, at best, a minority of the time. Any criminal can be pressured or guided to give a certain answer on a test.

[@Inkyminkyzizwoz]

Not to mention that something like a police interview can be quite stressful anyway!

[@edgarz7330]

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[@edwinebijohn6291]

Why??

[@taykforeal]

True a lie detector machine 😂 that's 1000% BS

[@flatsamiscool]

If I was taking a lie detector test, I’d be nervous because I’m nervous around anyone, I’d be nervous about taking the test at all, and if something happened to me, like if a family member was killed, I saw it, and they asked if I did it, I’d be afraid they’d think I did, and I would hate to have to think about what happened. If they asked if I was molested or raped, having to relive it would make me nervous. I’m not so sure we should believe them at all.

[@adelecotton1732]

The Underdog Music ooooh brb lemme check it out

[@adelecotton1732]

The Underdog Music its rlly good wow! subbed, liked and hit notif bell! i love ur music!

[@aoeu256]

I'd ask the prosecutors and the test administrator to also take the polygraph test at the same time, and instead of answering the questions I'd ask a counter question instead.

[@TheDreamBlog]

Yeah but many who take it nervous...which is why they ask the control questionsnto use as a baseline for when youre "just" nervous or very nervous.

[@Hard-Boiled-Bollock]

As I've said many times: If lie detectors actually worked every single politician would be out of a job

[@onlookerofthings6029]

If I had to take a lie detector test for a crime I didn't commit, I'd still be terrified even though I know it doesn't work and that I'm innocent because of what could happen to me if I fail

[@TMS5100]

Q: How do they work? A: They don't.

[@aoeu256]

Petty criminals are more likely to be uneducated so the threat of the polygraph test causes people to take plea bargains.

[@vicious12394]

As i always suspected the polygraph tests works by measuring your fight or flight response. This is a terrible way to determine if someone is lying or not but a great way to determine if they percieve the question to be a threat, which is not evidence of deception.

[@SKYREAPER30]

Yep shouldn’t be used for background checks in both gaming and law enforcement it’s just as stupid as believing in those psychic in the strip malls. Or like Scientologist believe in those cans to determine if someone has a bad soul 😡🙄. Just background check people and family and friends then you will find out who they are. This is just stupid sad they still use this practice today.

[@UltraWindow]

A great liar never lies :^)

[@mrmann673]

Damn.

[@falsereligionsunveiled7088]

Polygraph test (original counterpart middle age torture "if the metal burns you you are lying)) detects heartbeat, blood pressure, sweat. (Examples of criminal it didn't stop. Gary Ridgeway Alderick Gains and Charles Cullen) even the inventor thought it was an awful invention 1960s a polygraph expert experimented on plants and thought it had emotions

[@Sednas]

@@falsereligionsunveiled7088 I wonder where you got that information from.

[@hitormisshuh]

you have strict parents too don't you?

[@electricheisenberg5723]

@@Sednas adam ruins everything i would guess.

[@bacon.cheesecake]

SPOILER ALERT: they don't.

[@VincentGonzalezVeg]

i have ADHD so many things set off my adrenaline and startle me or make my blood pound fast for hours

[@FBI-5]

Vincent Gonzalez so if I say hey fuck you. You are gonna start drawing the Mona Lisa?

[@jessicarobb7590]

Vincent Gonzalez Thats what Im sayin

[@blastomanto5687]

same

[@ashh9666]

I was watching Jeremy Kyle and was curious

[@roosgreg6972]

AshH 96 I was watching Maury

[@Kjca_1998]

Same mate 😂😂😂😂

[@codypack4417]

Same actually 😂

[@leslynazaire5045]

me too

[@presleyrodrigues]

Me too

[@deemaaladhadh6306]

I’d be lying without even saying a word just because everything stresses me out

[@derrickmensah7189]

You've not met my friend yet...he can lie with passion😂😂

[@katrinavivianne]

B-but what if I have always had anxiety especially when confronted, I get jumpy when talking to people esp when under pressure.

[@jaimep456]

I remember watching that one Dr phil show where a mom thought that her son's gf killed him. The cops ruled the death as an accident but the mom was adamant about the girl taking a polygraph but the girl wouldn't because she didn't believe they were accurate. Then the mom and Dr phil made it seem like she must be hiding something becaude she wouldn't take the test. I hate how he bases most of his conclusions on those results like they're 100 percent accurate. I had this crazy friend who wanted me to take one. I had to cut that weirdo off real quick.

[@juliameyer10313]

Especially on "Dr." Phil, polygraphs are treated like the unbeatable determination of truth.

[@callofduty873]

What did they want you to take a test for?

[@arizonaboleynworley]

Yep ur completely right

[@petersmythe6484]

I just feel heart rate and breathing rate are not the same as lying. I am not particularly convinced by "lie detector tests".

[@Adumb_]

To answer the title, they don't.

[@mike2207]

The Underdoggg Music k

[@Handle873]

Yep this is why courts don't use lie detectors. A good liar won't be shaking and scared when telling a lie, so they would pass it even though they lied. And an innocent person can be scared even if they didn't do a crime.

[@st_us]

Jet fuel doesn't melt steel.

[@Flagen579]

Or does it?

[@BlackBirdJacobo]

it can.

[@shroomyesc]

7/11 jet fuel doesn't melt ice creams there were hot dogs planted into the towers!

[@XxRemixerzxX]

The jet fuel burnt the metal enough to weaken it which caused it to collapse

[@Rocky-rm4bc]

no fuel on its own melts anything. if you light it up it might :D

[@NKofman]

What if you know you're lying but you manage to keep your calm perfectly ?

[@crypton18]

I get stressed while telling truth because people might think i lie.😿

[@keaton6575]

I’m thinking about bringing a lie detector test to my school if they allow it

[@hancockautomotive1]

I subscribed. I lied. I was already subscribed. I'm a bad liar :(

[@teonyi]

Well if you confess right after of course you are.

[@gabrielvanlalruata2528]

I would be failing even tho' im not lying coz of my Anxiety Attack 😂

[@ｚ３ｎｔｒｏｐｙ]

The following sentence is true. The previous sentence is false.

[@nathanapocalypse1992]

BOOM

[@asmahussein4613]

Woooow

[@ExoticBloxed]

Zac Lee is this a riddle?

[@horseradish843]

Great video man.

[@MaxPSVR]

How many lives have been ruined by TVs shows like Jerry springer show where they ask have you cheated on your wife. And the lie detector said their lie.ing. Their should be something that helps repair the lives of those affected by this and the public ridicule. Family destroyed. Children loose their parents.

[@aoeu256]

Jerry Springer gives those guests money to appear on the show though...

[@BazamO]

There is no way to tell if someone is lying unless it's plainly obvious. There are probably billions of different factors that affect someones body for example you may be nervous if you take a lie detector test, not because you're lying but because you are just nervous and then the machine will tell you you're a liar.

[@raflamar4146]

The Polygraph tests your stress levels to see whether you are lying. But in that case, as long as you are totally calm during be testing you should be all good. If you aren’t stressed out after murdering those 25 orphans then the Polygraph shouldn’t really detect anything that would indicate that you were lying. If the murderer was an undiagnosed psychopath then they might not really feel regret over doing it, or once it’s done. And in the case of people who’s mental states prevent them from fully interpreting emotions then they might just not be able to comprehend the trouble that they are in. There have been a number of cases where the criminals took a lie detector test and passed as “innocent” just because they were calm, and didn’t panic. Cases such as: Gary Ridgeway, the Green River Killer. Soviet Spy Aldrich Aims. Serial Killer Charles Kullen. All they did was stay super chill and passed with flying colours. So yeah, if you end up in prison or on a show that involves the Polygraph, just remain super chill and you should be totally fine.

[@MrCatalin090]

person with high anxiety levels? guilty of every crime on earth.. person with no morals and doesnt care about anything(psychopath) the most innocent person on earth never agree to a "lie detector test" , and you know what's funny about it? it's never truth detctor test, they only care about "lies" and the only way they can detect a lie is if you are stressed , WHO IS NOT STRESSED WHEN DOING A SUCH AN INTRUSIVE TEST??

[@kingjamesviscotland241]

The fact that moles still get through the polygraph is proof it don't work.

[@Redactedredacted5837]

Lie detector don't work.

[@Hooverdarnit]

I took a polygraph TODAY and failed it though I was completely truthful. I'm sure I failed it because I was asked questions that I was supposed to lie about. Because the polygraph examiner instructed me to lie on certain questions, the fear of lying on those questions was none existent and couldn't possibly be compared to truthful questions. Before the test I showed him a photograph (that the prosecutor hid from me and my jury) that proved I was not guilty. Even though he saw a photograph that proved I was telling the truth, his polygraph says I failed the test. The fact is, the polygraph failed.

[@robinl4975]

Short answer: no Long answer: noooooooooo

[@justindie7543]

The best liars convince others that lying is wrong.

[@foxythepirate9823]

tysm! im working on a lie detector for my project!

[@fireaza]

You don't need a polygraph to catch spies, you just need a flamethrower!

[@305tzar]

The mythbusters in the US once put three of their guys into the polygraph test. It only helped to correctly discriminate 2 out of the 3 guys.

[@Owsikowy]

I actually am a pretty good liar... But I don't really like lies themself, so I do it rarely.

[@rustyknott-W.D]

I think a great test would be to hook the polygraph examiners up to the polygraph and ask them, yes or no, If they believe the exam is infallible.

[@piotrekiwn]

quality comments down there

[@sportsfaniguess154]

Short answer: No Long answer: Absolutely not

[@thehazelnutchannel6698]

I wonder why no one ask ‘do you trust lie detector test?’.

[@oddlysatisfiedviewer8568]

It can be used correctly. Just to determine if someone's stressed.

[@C_0_D_E1]

Lie detectors seem to be a great way of garnering business and making money. I'm from the UK and the main show that used it was the Jeremy Kyle show until it got canned. From what I gather, the Jeremy Kyle show always stated that their Lie Detectors were 96-97% accurate................. However, at an official Government Enquiry the show's Executive Producer couldn't give a straight answer as to how accurate the Lie detector tests actually were even when pressed on the subject by the Parliamentary Select Committee Chairman. As the executive producer you'd think he would have at least had that data with him when being questioned. Finally, in the UK, Polygraphs (Lie Detectors) are NOT ADMISSABLE in a court of Law as they are deemed too unreliable to be presented as a form of Evidence.

[@BANKO007]

It is even worse that it sounds because even if they do work for known lies (say, 70% accuracy), when testing unknown liars, you have to make an assumption about the frequency of liars in the test population. This prior assumption will often be the deciding factor. In other words, it is self-fulfilling.

[@limdarren3666]

what is that number thing at the bottom left of the video?

[@goldanima]

footnotes to the sources in the description

[@fanaticalpotato]

The number of the relevant footnote that's in the description.

[@limdarren3666]

ohh thanks

[@limdarren3666]

ohh thanks

[@benemles]

@@goldanima what the heck ? where are the sources in the video ? there ain't anything !

[@cynthiaharris4799]

My boyfriend says he wants to me take a polygraph test and if I don’t, he’s going to break up with me.. and it’s not even 100% accurate lol

[@Vxnilla_00]

let him go

[@Vxnilla_00]

3 months ago •... A fool always has to have a say.

[@creepystank420]

It takes time to realize lying does nothing. There's no price on peace of mind. I always tell the truth, but i don't do anything that constitutes me needing to lie. So that helps.

[@xxxxxrandom]

They don't work. Unless the tester tells to the subject that the machine shows you lied there, didn't you? and the subject says yeah I did.

[@jakobwolters3049]

yes I am! Is that a lie or not? ;) hmmm

[@Unknown-zj4ns]

Ussop should try it

[@AudoricArt]

that's easy. they don't.

[@narsplace]

What about lie detectors with fake memories?

[@kleptocat2478]

So... I could escape prison by literally being chill, and thats my attitude!

[@RAMROD1847]

I once betrayed an entire nation by giving them false information... does that make me a good liar?

[@liitleman5020]

They don't work if you suffer from anxiety are are naturally a nervous person in general. That's why courts don't use them. So there about 60% Accurate

[@Raiden-the-Goat32]

Not quite so accurate all though this is particularly correct. For instance anyone can have anxiety or stress under being giving a polygraph assuming they are capable of those emotions. So technically 99% of people if they tell the truth can still fail a polygraph. But let's take the missing 1% such as psychopaths who can not feel stress or anxiety they can pass while lying. When people say suffer from anxiety they typically mean anxiety disorder which is different from situational anxiety that basically every that is not a psychopath can have. Stress is something everyone but a psychopath can have to. In any case rather it's anxiety disorder or situational anxiety or stress a polygraph can be quite unreliable. So just being innocent and having a normal reaction to being questioned by law enforcement or the government over a crime investigation can cause you to fail. Honestly though being questioned by the government or law enforcement is quite stressful and anxiety inducing at the same time.

[@Kog233]

If you are being interrogated by the cops for murder, I would be nervous even if I was telling the truth

[@FakeButt]

Good job on the lighting! You can definitely see the improvement by comparing his skin tones to the ones in the video in the annotation at 4:57

[@vladneacsu5212]

And if someone is stressed al the time and they also tell the thruth? :))

[@crazyentertainment4842]

Sometimes people react like lying when telling the truth

[@AreyemMeyera]

I'm still waiting for the question to be answered. Does it work?

[@dominiccolangelo4965]

Me: Looking up if lie detectors actually work Steve Wilkos: You weren’t supposed to do that. I am addicted to the show tho

[@maxhomax1364]

Fraaaaannnccce

[@jennifertenorio2588]

I was watching Maury and wanted to know 😂

[@MrEccentricities]

a machine that is going to be responsible for someone believing you or something yeah not gonna stress anyone out

[@carelesswhisker4155]

Yeah but what other reason could a person have to be stressed during a police interrogation

[@Raiden-the-Goat32]

What reason could a person be stressed during interrogation? 1 Let's see being put in jail over a crime you did not commit which is very common. 2 an inaccurate test causing the police to target you for a crime you did not commit. 3 interrogation's themselves are stressful especially when they can last for long periods of time. Some going for 3-4 hours. 4 police trying to force a confession using fear tactics for prolonged periods of time not caring if the person committed the actual crime. I mean false confession's are very common because a cop either not caring about an honest confession or just being shit at his job. Point in case what reason would an innocent person be stressed under police interrogation? Plenty .

[@JaapVanderHorst]

Were is scientific proof it works at all? and why is it never used at all in European countries. Does that not make you think?

[@MrRolnicek]

I never lie and everyone knows it. ... ... So if I were to tell a lie at some point, ...

[@nocturnalsingularity3138]

I'd say, you have more of the face of a man who just tossed his wife off their Yacht, after tennis practice, then showed up on time for dinner at HER parents house. All in time to play worried with everyone else when wify is a no call no show

[@geoffjames992]

I'm a good liar. Or am I?...

[@ZHP330]

Coin flip is same accuracy

[@seanhills6187]

No offense he does kinda look like a video-game villain, maybe from Dishonored?

[@splashaf]

sean hills if you have to say no offense it's gonna be offensive

[@yea1]

I'm lying.

[@mikaMKP]

"Flighting" Greg, really? ;o) Good video, though. Thanks!

[@ScorpioHighlander]

Me? I'm a tribal liar. No one has ever believed a word I've ever said. So am I? Eh? Eh?

[@asshoo1]

No, I'm not ;)

[@bentoth9555]

This whole video could have been you saying "not really" and then standing there for a bit.

[@isaywhateveriwantandyougot7421]

No

[@al.s.3277]

It’s like people trying to scientifically explain beauty. There are simply no facts it’s all subjective.

[@5u5annah]

Quoves lol

[@slyfer5321]

I am a liar, do you believe that I am a liar?

[@Cha0ticHarm0ny]

Y would be stressed before the question

[@Saumiiiii]

LMAO

[@grachogracho5918]

In the oppeside way like, truth printer done....

[@saeedurrahman2056]

The simple way is a person is actually lying about something just be calm take a deep breath an focus on something else I guarantee the lie detector won't work I mean is unreliable

[@oi6925]

I was just watching Steve wilkos

[@johnnychang4233]

Why polygraph isn't applied to presidential candidates?

[@rhynosouris710]

johnny chang What would be the point? We already know they're liars

[@shanematthews1985]

I lie on a daily basis, but most of these are white lies, i work in retail and thats my excuse :P

[@BrokebackBob]

No excuse. Sorry, you're a liar.

[@DannySullivanMusic]

Keep lying to yourself

[@lutu1321]

I don't trust polygraphs

[@chadgould7453]

Yer well what if your life is threatened over a lie n truth is only thing to keep it

[@ryanschroeder9749]

Yes I am a good lier

[@banterlad1514]

I only trust James May

[@thedairylord7861]

I guess you just proved that true story video with the lie detector is false

[@CaitlynDover]

My dad had to be polygraphed and had an extremely in-depth background check done by the FBI to work for a nuclear power plant! I always thought it was insane and way too over the top, but never did I think a spy would try to infiltrate the Tennessee Valley Authority- Nuclear Power Plant. Why though? What would they accomplish? Granted my dad was pretty high up the totem pole, but still...why would a spy want to know the inner workings of a nuclear power plant?

[@albinblomdahl4489]

I mean I guess a spy would be quite interested in either to steal nuclear-plant technology superior to where the spy came from, or if the spy's boss had more serious intents maybe to try to sabotage it or blow it up. Nuclear energy can be very destructive if it gets fiddled with, as we've been told by hiroshima/nagasaki and verious tests

[@CaitlynDover]

@@albinblomdahl4489 I'm going to ask him about this now! You've peaked my interest. It's insane the things he had to go through to secure his position.

[@evanb.6150]

In the polygraph I took (with the government, so it's a legit one), the control questions weren't super incriminating questions. Rather, they were basic-beyond-belief stuff, like "is today Thursday?" yes. "is today Friday?" no. Etc. And my practitioner said that after administering thousands of these tests, she was very confident that for every incriminating signal picked up by the test, there is some real reason for it (few false positives), and they are learning more about catching the ways in which people cheat the system (fewer false negatives).

[@WynneL]

Well, that person is an idiot. A psychopath will not feel guilt about lying, which is why they can pass polygraphs. An innocent person with anxiety will think, "oh god, this question could get me thrown in jail" so their heart rate and other vitals will increase in response. No amount of baselining will do a damn thing about those factors, and polygraphs are therefore bs pseudoscience that will *NEVER* do anything more than (a) prejudice investigators, and (b) lead to false confessions from innocents who think "if the infallible all-knowing polygraph says I did it, I must just not consciously remember that I did."

[@jibjab1408]

Are you saying that a person who makes their living from polygraph exams said that polygraph tests work, or will work eventually?

[@MysteriousStranger42]

Nope

[@stefanbrown8176]

No. Simple

[@animegod6060]

I'm a sociopath

[@speedkiss22]

mmm no bitcoin adress

[@rafelemay5070]

When I was much younger and really wanted a certain job, I beat one. I see they have shown that men that were clearly innocent lying.

[@Hunter-bm6ss]

well seeing that i have to hide 75 percent of myself from my family yes i am a vary good lyre