Is it possible to fail a lie detector test when telling the truth?

11 Answers

  • 2 months ago
    Favourite answer

    Yes.  That is why they are not admissible in most courts of law.  The test can not measure lies or truth.  It can only measure body reactions.  It checks things like pulse, temperature, etc.  If those raise, that is usually an indication that you are lying.  But it can also be caused by your being nervous.  Or many types of medical conditions.  

    A few years back a friend of mine who was a police officer was given a lie detector test to try to see if he was prejudice against black people.  He was told that was the purpose of the test, and it would be looking for body reactions when in a series of phots he was shown a black person.  Of course, knowing that he did not dare to react to a picture of a black person, his nervousness made him reaction by trying not to react.  The person being tested was black.  So it seems unlikely that he would be prejudice against black people.  But the test showed that he was because  he was warned not to react which assured that he would react.

    Lie detectors are not always accurate.  They often are, but not to were they can be used in courts.

    (Interesting the side note.  The inventor of the lie detector was also the creator of Wonder Woman and wrote the her comic series for over 20 years.)

  • Anonymous
    2 months ago

    Yes, because people can just look at the results and computers make mistakes, plus the fact that good liars can get away with lying is another piece of evidence to the puzzle. I don't want to answer to what others are saying but that is why these aren't admissible in court. I never took a lie detector test but I looked at videos where people are getting looked at or watched, usually lie detector tests are used to prove if someone is cheating on them. All the computer can do is read emotions and stress levels and convert them to a threshold, then they will determine whether it is a lie or the truth. Since computers are inaccurate most of the time, it's usually one of the reasons that these are the machinery that I do not trust. People can also change the algorithm or results as well. Even though I hardly see that happen, I hate lying as I have no reason to lie. If you are telling the truth then you'd best better have evidence as well like a recording for proof because people will look at that. What happens depends on the situation and severity of the offense as where you are failing the test, like if you are charged with murder and they use lie detector tests which is a high severity case, and you claim your innocent, the judge can't go by the lie detector, they need full proof that you murdered someone with fingerprints and all that necessary evidence that they use, whether someone got it on film or found a knife or firearm registered with your serial number or name. Otherwise if it is for something that is not as offensive like, 'your girlfriend saying she is cheating on you' or 'you stole a pack of gumballs, (in case you ask) the worst that can happen is you getting humiliated and dumped by your girlfriend or (getting probation for theft of stolen item), hopefully you don't see cameras around, usually you will. Unless your girlfriend is forgiving and you can work it out later, then you would be able to say look, "I never cheated on you, I can't lie and I wouldn't lie to you, I swear by the bible and God, that I would never cheat on my loved one." If you are in this situation, just respectfully say "I did whatever it was that they said you did or didn't do", then work it out later. The last thing you want is to be looked at as a liar or accrue more unnecessary attention, God knows whether you are telling the truth or not, People wouldn't be able to tell if I am lying because I get stressed and emotional almost every day from work. People can say you lie or feel you lie, but that is their reasoning. However, another example, is if you stole a pack of gumball, since it requires you to go to court, they can't use a lie detector test to put you in jail and you can't go to jail for stealing a gumball, because that isn't sufficient evidence or valued enough to be theft to put you in jail. Why do you think they have cameras in stores?

  • RICK
    Lv 7
    2 months ago

    yes and because it is they are not admissible 8n court

  • 2 months ago

    That's the exact reason polygraph tests aren't admissible in court.

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  • 2 months ago

    Sure it is possible.  Happens all the time.  Lie detectors are fake machines.  There are numerous ways to screw up the recording.  They are used to intimidate people and that is their only use.  The law can and does lie to people in investigations and interviews,  But if you tell just one lie, that is a felony.  Keep your mouth shut and refuse any lie detector.  That is your right. 

  • Lv 4
    2 months ago

    YES. if you are not confident about what you are saying then that machine can tell 

    You are lying even though you are saying truth. 

    All that machine does is measure your response & reactions. So I wouldn't even call that response measuring machine a ' Lie detector "

    You can get away with lie with you are very good Liar. I have tried it & proud to say that I got away with lies 😉😛😎

  • 2 months ago

    All a "lie detector" does is detect a strong emotional reaction to a question could evoke said reaction.  A well trained, experienced polygraph operator would be able to discern if a reaction was indeed a lie or just a reaction to the question.  i.e. "Do you ever watch pornography?".....Could be that your vehemently opposed to porn and it causes a detectible reaction to the question.  (For those of you that say that lie detector results are not admissible in court....For the most part that's true, BUT they ARE allowed in Federal Court.)

  • Foofa
    Lv 7
    2 months ago

    Yes, polygraphs are notoriously unreliable, which is why they're not admissible in court. 

  • 2 months ago

    YES.  In fact I did ... MULTIPLE TIMES.  

    Scientific research on the polygraph show that it is NO BETTER THAN CHANCE at detecting truth or lie in MOST situations.  There are a few narrow applications where it does better than chance, but still has an unacceptably high false positive and false negative rate.

    In short, it's worthless.  Even it's INVENTOR denounced his own invention late in life.  It was created based on NO EVIDENCE whatsoever that heartrate, perspiration, and breathing rate correlated with lying.  Many of the most damaging spies in US history passed MULTIPLE polygraph tests, like Aldritch Ames.

    So why do they use it?  A retired FBI official once told me that they only use it to intimidate people they already know are lying.  So for example, say a prison inmate suddenly claims he can identify where Hoffa was buried in exchange for time off his sentence.  The FBI knows he's full of sh_t, and to spare themselves the work of having to prove it, they challenge him to take a poly under penalty of perjury.  Because he believes the poly is real, he withdraws his claim.

    But the intelligence community is still using it as a condition for employment to many jobs.  Why?  Because in the hands of a skilled interrogator, the fake psychological pressure that the poly creates can cause people to be more honest EVEN IF IT DOESN'T ACTUALLY WORK.  It's a bluff.

  • ?
    Lv 7
    2 months ago

    It happens a lot, as a so called lie detector only measures physical body responses to a question.  Not if someone is actually telling the truth. 

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