How accurate is a polygraph?

Discussion in 'General Information & Discussion' started by Kimster, Jan 24, 2011.

  1. Kimster

    Kimster Former Member

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    This is a spot to discuss whether polygraphs are reliable - or not.
     
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  3. Kimster

    Kimster Former Member

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    This is just one site's opinion. There's a lot of pros and cons that can be found on the internet!

    "How accurate is a polygraph?
    While the polygraph technique is highly accurate, it is not infallible and errors can occur. According to the American Polygraph Association over 250 studies have been conducted on the accuracy of polygraph testing during the past 25 years. Recent research reveals that the accuracy of the new computerized polygraph system is close to 100%." <snipped>

    http://www.truthorlie.com/accurate.html
     
  4. Kimster

    Kimster Former Member

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    Did you know they don't polygraph pregnant women?
     
  5. Gypseagirl

    Gypseagirl If JA gets off-there is absolutely NO Justice!!

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    Very interesting...I wonder why that is?
     
  6. Kimster

    Kimster Former Member

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    I heard a fellow on NG say it's because they can get a reading on the baby's reactions somehow. Yes, that is pretty interesting!
     
  7. Gypseagirl

    Gypseagirl If JA gets off-there is absolutely NO Justice!!

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    I never thought about that but it does make sense. Thanks for the info :)
     
  8. OldSteve

    OldSteve Active Member

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    As one who lives with chronic pain, I found it interesting to read that you cannot be in pain during a polygraph...
     
  9. HesterMofet

    HesterMofet Member

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    if polygraphs are so accurate, why aren't they allowed in court? Certainly if they were even as accurate as eyewitness testimony (which is notoriously unreliable), they would be allowed as evidence.

    The website that is mentioned is a pro-polygraph site. I would like to see independent studies on the accuracy of polygraph testing.

    Another issue is that they won't work on true sociopaths/psychopaths who have no guilt over what they have done. If they aren't emotionally heightened or stressed, they won't trip up the polygraph.

    Even if I were clean as a whistle, I would never take a polygraph. Way too many variables and chances for things to go wrong.

    I hate it when I read on here, "He must be guilty! He refused the polygraph!"
    That's just crap.
     
  10. Kimster

    Kimster Former Member

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    "Researchers conducted 12 studies of the validity of field examinations, following 2, 174 field examinations, providing an average accuracy of 98%. Researchers conducted 11 studies involving the reliability of independent analyses of 1,609 sets of charts from field examinations confirmed by independent evidence, providing an average accuracy of 92%. Researchers conducted 41 studies involving the accuracy of 1,787 laboratory simulations of polygraph examinations, producing an average accuracy of 80%."

    http://www.polygraph.org/section/resources/polygraph-validity-research
     
  11. tlcya

    tlcya Well-Known Member

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    MOO (yep, brought my cow with me, seems I take her everywhere now) is that a poly is only as reliable as its administer. I do believe it is right that they are not allowed in court. I think there are just too many variables involved in such an examination to consider it conclusive, hence its unrelaibility in a court as evidence. I do feel it is a valuable tool in the investigative process as it can help investigators get a feel for if they are on the right track or need to look at other angles.
     
  12. Kimster

    Kimster Former Member

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    Do you guys think polys are useful at all?
     
  13. OldSteve

    OldSteve Active Member

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    Won't like to find myself in that 20% of inaccuracy....

    I think it's very tricky, and so much depends upon the questions being asked... simple yes/no answers when a person might have guilt feelings indirectly related to what&#8217;s being asked&#8230;.

    Since LE is allowed to lie to you in interviews, how does one find out the real results?
     
  14. rossva

    rossva George Zimmerman: Innocent until proven guilty.

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    I have taken a polygraph, after my house was involved in a home invasion. I was the victim, treated as the perp, answered every question 100% honestly, and was told I "failed miserably". I had absolutely no knowledge, or involvement with the home invasion, was 100% a victim. This was in Brevard County Florida.

    I did get an apology from them when a few weeks later they caught some one doing a home invasion elsewhere in the county, who confessed to a string of them, my house being one.

    But in short, I can see why they are not used in court (unless both defense and prosecution agree) - imho, they are worthless.

    When I took mine - I was in the room with the interviewer just talking with him (unhooked) about the home invasion, and he went over the exact questions he was going to ask three or four times with me, almost so I could formulate an answer for the real test.

    I was told to lie to a particular question. He held up a card with the number 4 on it and asked if the card had the number 4, and I was told to lie and say no. Other standard questions were asked, such as is John Robert Doe your name is 1/1/60 your birthdate, etc. I was also asked questions that I felt had no bearing on the home invasion, and questions that were very ambigous. I had the tester clarify some questions, such as "Have you ever taken anything of value form some one that loved or trusted you?" "Ever? Well, I took a dollar out of my mom's purse when I was 9, does that count?"

    There were questions that I never really understood. The incident happened when I was 48, and the questioner prefaced a lot of questions with "prior to your 46th birthday did you ever....".

    I was then hooked up to the machine. All in all I was asked about 50 total questions, with several of the questions repeated more than twice during each session. I was officially asked the sets of questions three times.

    The questioner afterwards told me I passed all questions except one where it showed deceit when asked if I felt responsible for the home invansion - explaining that was natural, because since I was insured, it was a victimless crime, did I in some way help them, etc - at the time I didn't realize it but in retrospect, I think I passed those questions too, and he was trying to trick me into a confession. I was never shown a copy of the polygraph, or a copy of his evaluation of it, but on a copy of the final police report, the investigating detective said I had showed "extremely high levels of deciet, and not only failed, but failed miserably.
     
  15. strach304

    strach304 New Member

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    I saw that show. He said they won't do them after the first trimester. He also said a LDT causes a lot of anxiety in addition to the current stress of a missing child.
     
  16. weedemout

    weedemout Member

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    If a person can control their emotions and nerves, these machines are useless. For the rest of us, they are probably 100% reliable. The question then becomes is the person innocent or good at controlling their nerves? Thus why it's not allowed in court. My general thinking is that they are probably useless, but in some cases they may give some insight.
     
  17. MLE

    MLE New Member

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    That's why I would never take one. For them to be nearly 100% accurate, I've seen so many of those shows on ID channel where murderers have passed their polygraphs while innocent loved ones of victims have failed.

    If they were truly 100% accurate, it would be an asset however.

    Plus, I like to give long, detailed answers and would be worried a cop would start yelling, "JUST ANSWER THE QUESTION!!!" lol.
     
  18. Tracker

    Tracker New Member

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    HesterMofet, Yes so many variables can alter the results of a poly. One variable is the examiner's personality themselves. The tests have been known to read *Inconclusive* repeatedly. I know this as fact in regards to one particular examiner in the St Pete/Tampa area whose attitude is brutal...

    The poor kid who had to take the poly got told it was *Inconclusive every time this guy did it and made him return half a dozen times. The teen was not lying. he was not hiding anything. Yet the test was always *Inconclusive* and therefore the examiner stated the teen MUST be hiding something when in fact he was not.

    Ended up that the young man finally was allowed to take the poly with a different examiner in the area and he passed - I have personally met the examiner and he is a stand up guy.

    I have a friend who took the poly for a job many years ago - mall security. *C* took the poly, and failed it..She could never lie it wasn't in her to be dishonest lol. She did end up getting the job after all...

    SO many variables....
     
  19. STANDREID

    STANDREID A slacker when slacker wasn't cool

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    Aldridge Ames, the Soviet spy, passed multiple polygraphs. Also passing their tests were Richard "The Wood-chipper Killer" Crafts, Mark "The Mormon Bomber" Hofmann and Gary "The Green River Killer" Ridgway.

    On Kraft Suspense Theater it was called The Machine That Played God.

    I think your attitude toward taking the test may actually be at least as important as the test itself. If you quickly and enthusiastically agree to take the test, after letting authorities bring it up first, then the assumption is going to be that you are innocent. I know because I did just that and the police were so impressed that they didn't even make me take the test. And to be clear, I was actually innocent too.

    A lawyer would have told me not to take the test but he wouldn't know I was innocent where I did.

    I saw somewhere they are about 60% accurate so flipping a coin plus 10%.
     
  20. JBounds

    JBounds I feel lucky

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    I think it was useful in the Susan Smith case. Susan's test showed that her greatest level of deception was when she was asked the question; "Do you know where your children are?"

    Other than that I don't think they are that useful. They can wrongfully accuse and people are able to beat them.
     
  21. Fuze

    Fuze New Member

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