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Challenging The 'Unbeatable' Polygraph 101

Posted by timothy
from the scuffle-worth-scuffling dept.
George Maschke writes "Dr. Louis Rovner, a prominent California polygraph operator, has (through PR Newswire) issued a press release titled, 'Polygraph Unbeatable, Says California Psychologist.' All too often, such publicly-made claims by those with vested interests in the perpetuation of polygraphy (a make-believe science that offers make-believe security) go unchallenged. So, I've publicly challenged Dr. Rovner to support his claim and pointed out scientific research that contradicts it, as well as the examples of several notorious spies and a serial killer who have beaten the polygraph. See, A Public Challenge to Dr. Louis I. Rovner."
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Challenging The 'Unbeatable' Polygraph

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  • So... (Score:2, Interesting)

    by Anonymous Coward
    As I read it he isn't claiming the polygraph to be 'unbeatable' and concedes that some people may be able to beat it but most can't and certainly not by reading a book. More importantly, who cares? Last time I checked polygraphs are generally inadmissible by law.
    • Re:So... (Score:2, Insightful)

      Since it was Dr. Rovner's press release, I presume that it is he who selected the title, "Polygraph Unbeatable, Says California Psychologist."
      • Re:So... (Score:1, Insightful)

        by Anonymous Coward
        The title is really irrelevent, the article clearly doesn't suggest that the test is "Unbeatable". The first sentence of the release by Dr. Rovner contradicts this.

        "Almost no human being can beat a polygraph test"

        Almost being the operative word.

        • Re:So... (Score:5, Informative)

          by George Maschke (699175) on Tuesday October 26, 2004 @08:54AM (#10629922) Homepage
          And the claim that "almost no human being can beat a polygraph test" is flatly contradicted by the research to which I referred in the linked public challenge [antipolygraph.org], wherein some 50% of polygraph subjects were able to fool the lie detector after receiving a maximum of 30 minutes of instruction...
          • You fail (Score:5, Insightful)

            by SmallFurryCreature (593017) on Tuesday October 26, 2004 @09:51AM (#10630301) Journal
            What you show is that people can defeat the polygraph if they are lying. What is far more important is if the polygraph says people lie when they are telling the truth.

            Falls positives is what I am worried about. People being convicted because they were nervous and upset about being charged with something they didn't do.

            • Re:You fail (Score:4, Insightful)

              by idlethought (558209) on Tuesday October 26, 2004 @10:20AM (#10630552)
              Think about it a step further along..

              Suspect A lies under polygraph implicating Suspect B - polygraph indicates he's telling the truth.

              Suspect B is interviewed, shown 'proof' that he committed the crime, offered a deal..

              False negatives can be just as dangerous if they are believed..
        • Re:So... (Score:3, Insightful)

          by lobsterGun (415085)
          he alose says that they are only 96% effective when done properly.

          Apparently, 4% of the population constitutes "Almost no human being".

          • Re:So... (Score:2, Funny)

            by Anonymous Coward
            Hey, what's 24 million people between friends?
            • Re:So... (Score:2, Funny)

              by Anonymous Coward
              With a population of 6 billion you should be saying whats 240 million people between friends. But hey, whats 216 million people between friends.
              • Re:So... (Score:2, Funny)

                by Anonymous Coward
                Actually, I was using the British definition of "billion", but hey, what's an order of magnitude between friends?
                • Actually, the difference between a British billion and an American billion is three orders of magnitude.

                  But what's two orders of magni...


                  oh, never mind
    • Re:So... (Score:3, Insightful)

      by kalidasa (577403) *
      Well, for one, there are those who would like to make polygraphs admissable by law.
    • Re:So... (Score:5, Insightful)

      by lobsterGun (415085) on Tuesday October 26, 2004 @08:51AM (#10629902)
      While it is true that you cannot be convicted on the basis of a polygraph, would you want the news that you had failed a polygraph leaked to the press?

      Even if you aren't acused of a crime, consider that you can still lose your job because of a failed polygraph.

      Polygraphs are bad science; They should not be used as the basis for making decisions.
      • by macz (797860)
        I can't imagine how the effects of a polygraph test being leaked to the press somehow have more integrity than the reports of a psychic being leaked to the press.

        What I mean to say is I can imagine how it got to the point where a polygraph is somehow more credible than a psychic.

        It is like Scientology and that bogus E-Meter [celebritycentre.org]. Just because it uses "technology" doesn't mean it is valid.

    • Re:So... (Score:4, Interesting)

      by Evil Schmoo (700378) on Tuesday October 26, 2004 @09:25AM (#10630126) Homepage
      True, polygraphs are inadmissable as evidence in a court of law. But that's not the main point.

      As anyone who works for a defense contractor or secure government facility can tell you, polys are the ONLY way you can get to levels of clearance above Top Secret (TS). In fact, there's TS, and there's TS-Poly above that, and then there's all the ones we can't tell you about above them.

      The fact is, people beat polys and get into extremely high levels of clearance. I personally know people who have (mostly on the drug use questions). Now, these folks are my friends, and generally good people, so I don't really have a problem with them per se -- but claiming that polys are indestructible perpetuates the mindset of the higherups that polys don't lie. I'm not saying that the GAO and DOD don't perform good background checks -- they do -- but using polys as a check of last resort leaves a fairly large hole in our nation's security net.

      Would you really want a bright young programmer to get a job in No Such Agency or DIA while having claimed his father was from Kuwait instead of Yemen, all on the strength of having beaten a polygraph?
    • Ah, but would he make the same statement while undergoing a polygraph test, and if so, what answer would the machine give?

      BZZZZZ...

  • Yes. I mean no. I mean... I think I'm not sure. Well but... Maybe... Well if you put it that way... erm. No? *BBBBBBBBZZZZZZZZZZZZZZZT* "What is your favourite color?" "Blue! ... No Red!" "Aaaaaaaaaahhhh..."

  • I'm sure all the Slashdot readers who are notorious spies or serial killers will take heart at this!

  • The problem is... (Score:2, Insightful)

    by hivemind_mvgc (823238)
    ...that they make you take off your tinfoil hat for a polygraph.

    Otherwise, I'd be good.

  • 96% accurate? (Score:4, Informative)

    by hankwang (413283) * on Tuesday October 26, 2004 @08:42AM (#10629850) Homepage
    From the first article:

    "Overall," says Dr. Rovner, "we are confident that polygraph tests have a 96% accuracy rate when done properly."

    If that is true, then if you have 1 spy and 49 honest people, this polygraph will likely falsely accuse two honest people as being spies.

    • Re:96% accurate? (Score:5, Interesting)

      by George Maschke (699175) on Tuesday October 26, 2004 @08:50AM (#10629899) Homepage
      Right, even a test that is accurate 96% of the time is going to produce many more false positives than true positives when the base rate is low.

      But while Dr. Rovner asserts that he is "confident that polygraph tests have a 96% accuracy rate when done properly," the scientific community has no such confidence in polygraphy. The National Academy of Sciences recently published a report titled The Polygraph and Lie Detection that concluded that the theoretical basis for polygraphy is quite weak and that that almost a century of research provides little basis for the expectation that the polygraph could have an extremely high rate of accuracy.

      • Re:96% accurate? (Score:2, Interesting)

        by digitalchinky (650880)
        As part of DSD's 'Welcome Boeing Contractors Day' they were giving out polygraph tests at gunpoint. (Well, not really gun point, but 'you don't take it, you don't come in on Monday morning - idle threat') After being wired, they start out asking really silly questions - What is your name? - Like they don't KNOW already? They chatted with DSB - those positive vetting weenies. They know everything.

        I'd just watched a show on Discovery about how to 'defeat' polygraph! Turns out it more or less is beatable with
      • I'm more inclined to consider a lie detection method that's based on behavior than one based on a machine that records vital signs.
    • The question is whether that 96% figure refers to false positives (specificity), as you take it, or to false negatives (sensitivity), as Maschke thinks. My guess would be that it's the latter, but the failure to make that distinction, as well as the general tone of the press release (and the fact of having a press release!) tend to diminish Rovner's credibility.

      On the other hand, George Maschke's inability to comprehend the distinction between "almost no" and "no" doesn't do him any favors either. I'd file

      • Re:96% accurate? (Score:2, Interesting)

        The truth about polygraph matters (to Americans, at least) because, despite the recommendations of the National Academy of Sciences, the U.S. Government continues to rely heavily on the polygraph for purposes of national security and public safety.

        When advocates of the polygraph make such dubious claims regarding polygraphy as Dr. Rovner did, I think it is important that they not go unchallenged.

      • Neither is right. The 96% is usually referring to the confidence interval that the machine returns an output within specifications (in this case Truth when the person is telling the truth and Lie when the person is lying).

        I'm currently taking a class (Industrial Engineering 423: Statistical Quality Control) where we learn how to set the specification range, confidence intervals, and machine capability. Things like 6sigma and ISO(pick a number).

        It's actually quite interesting learning how companies manip
    • Base Rate Fallacy (Score:5, Insightful)

      by hey! (33014) on Tuesday October 26, 2004 @09:16AM (#10630054) Homepage Journal
      What you are referring to is something that is called the "base rate fallacy". This mathematical fallacy occurs when you try to interpret the results of a test without taking into account the frequency of the thing being tested for in the population being sampled.

      Taking the claimed 96% accuracy rate as a given, suppose that 1/10K people are terrorists. If I randomly polygraph 10K peple, I'll on average turn up 1 terrorist and 400 false positives. I can only be 1/4 of one percent sure in my result.

      On the other hand, suppose I know that 50% of the people working in an office are stealing supplies, but I don't know which. If I test 100 people, I'll get 4 false positives and 48 true positives. I can be 92% positive than any person who failed their polygraph steals office supplies.

      The lesson is this: evidence can only be weighed in context. There will probably never be a single test that can determine the truth on its own.

      • On the other hand, suppose I know that 50% of the people working in an office are stealing supplies, but I don't know which. If I test 100 people, I'll get 4 false positives and 48 true positives.

        And is the employer prepared to fire 52% of his employees, including the ones who didn't do anything wrong? I'd say you typically use a polygraph to identify a small fraction of your population. An exception may be a screening of job applicants.

        Anyway, I agree with antipolygraph.org that it is all a bunch of p

      • Taking the claimed 96% accuracy rate as a given, suppose that 1/10K people are terrorists. If I randomly polygraph 10K peple, I'll on average turn up 1 terrorist and 400 false positives. I can only be 1/4 of one percent sure in my result.

        But that doesn't really matter much in the context of screening job candidates for the govt. If you screen 10k applicants and throw out 401 of them for being "possible terrorists" you're still left with 9599 people to pick from. Hardly much of a loss even if 400 of the on
    • by hummassa (157160) on Tuesday October 26, 2004 @09:19AM (#10630080) Homepage Journal
      She can tell when I'm lying 100% of the time....
    • "Overall," says Dr. Rovner, "we are confident that polygraph tests have a 96% accuracy rate when done properly."

      If that is true, then if you have 1 spy and 49 honest people, this polygraph will likely falsely accuse two honest people as being spies.

      I can see two problems with this comment. One is that he doesn't state what that "96% accuracy" rate really means. That could mean that it's able to catch 96% of lies, which would be pretty good, or it could mean that it incorrectly calls the truth a lie 4

    • not exactly. 96% statistical accuracy means that if you have a population of 49 honest people and 1 spy (or H honest people and S spies for a total population of H+S) that it will pick out the S spies 96% of the time.

      to have what you suggested, the test would have a 96% "POWER" (or a 4% beta error for n=50).

      Alpha error (Type I error) = Probability(X returns false | X is actually true) => false negative
      Beta error (Type II error) = Prob(X returns true | X is actually false) => false positive

      The actu
      • (.96^47)(.04^3) = .00000939 or 9.39 per million

        What distribution are you using?

        The model it looks like your are describing is binomial with probability of success 0.96. If that's so, the probability of having exactly 3 positives is .18, and the probability of having at least 3 positives is .32. That's a 1 in 3 chance that you are falsely accusing 2 or more people.
        • It is the binomial, but you aren't applying it properly.

          A 96% probability says that "We are 96% confident that the Lie detector will get it right." So p=.96 and q (or 1-p) = .04.

          To expand:
          If the person is honest, there is a .96 chance the machine will return H(onest) and .04 it will return S(py). If the person is a spy, there is a .96 chance it will return S(py) and .04 chance it will return H(onest).

          The original poster postulated that if there was 1 spy and 49 honest people, that it would return 4
          • OK, we agree, if nothing else is specified, that "96% accurate" means: If the person is honest, there is a .96 chance the machine will return H(onest) and .04 it will return S(py). If the person is a spy, there is a .96 chance it will return S(py) and .04 chance it will return H(onest).

            Now you calculate, for a population of 49H, the chance of detecting 47H + 2S(correct) + 1S(false):

            .96^47 * .04^3 or 9.9 per million.

            Talk about "know your statistics". It should of course be: .96^48 * .04^2 * 49!/(47!*

            • Talk about "know your statistics"....

              We calculated 2 different things. You calculated 3 S (1 correct, 2 false). That wasn't the original poster's posstulate. His was 2 S (both false) which implies one of the H's is false as well. As for the factorial part, that isn't used because the order is irrelevant and the individual trials are not dependant on each other. The first guy has a .96 chance of being correct regardless of whether he's H or S.

              I was calculating the odds of exactly 2 false S and 1 fa
              • As for the factorial part, that isn't used because the order is irrelevant and the individual trials are not dependant on each other.

                Whoa, missed this earlier. I think you have a major mistake in there: The factorial part IS USED because the order is irrelevant and the individual trials are not dependant on each other. The factorial part accounts for all possible combinations of 47 successes and 3 failures.

                Consider the simplified example of three people taking the polygraph test and you'll see you mus
          • It is the binomial, but you aren't applying it properly.

            Okay, well what is the probability distribution function for the binomial distribution?

            The probability is:
            H[.96 * .96 * ... (44 more) ... * .96 * .04 * .04] * S[.04]
            Which simplifies to .96^47 * .04^3 or 9.9 per million.


            .96^47 * .04^3 means you will get exactly 47 successes followed by exactly 3 failures in exactly that order, which seems strange. However the probability of exactly that outcome is what you say, about one in 9 million.

            If
  • remorse (Score:3, Interesting)

    by Anonymous Coward on Tuesday October 26, 2004 @08:53AM (#10629914)
    Most polygraphs work on the idea of remorseful feelings the subject will have if they report a lie in response to a question. Indeed they are beatable - most murderers and other criminals would not give off remorse when asked questions, thus the machine interprets the response as the "truth". This is the main reason polygraphs cant use these results in court.

    Thus, when polygraphs are used, it's important it _not_ be the only tool used. For instance, when the USGov't investigates someone applying for a security clearance, they check everything in addition to using the poly. Credit history, school records, school/military diciplinary records, tax records, medical history, family medical history, they perform various psychological exams, they talk to the guy's friends and co-workers and supervisors, and so on. They ask questions about international travels, friends who are non-US citizens, etc.

    This way, when someone "passes" a poly, there's evidence to back that up or refute that result. If the investigate report backs up a positive polygraph result and nothing negative is found (or the negatives are manageable), then the guy can probably be given that clearance. Otherwise - the red denied stamp gets pulled out. Indeed, someone can pass the poly and still be denied the clearance - such as a black eye on the credit report (espionage risk - if the guy falls behind on mortgage payments, he could sell secrets to whomever wants them) or a history of alcoholism (clumsiness with classified material risk - if the guy gets drunk while acting as a courier, he risks losing it).
    • Re:remorse (Score:3, Informative)

      by Anonymous Coward
      That's not totally accurate.

      A polygraph works based on relative stress. Usually it goes as follows:

      First they ask some "control" questions. These are questions they already know the answers to. From that they determine your baseline responses. Then they start asking the real questions. They will usually introduce more control questions during this process so they can make sure the baseline is still working (you won't know which are the control questions during this phase).

      Do beat the machine all you
      • Do beat the machine all you have to do is fuck up the baseline. There are different ways of doing this. If you can cause physical pain to yourself that will stress your system.

        There was a very short-lived TV series on FOX in 1996 called Profit [tvtome.com]. There was one episode where the main character took a polygraph test. Before the test, he put a tack in his shoe and stomped it into his foot. They showed him bearing down on that foot for certain questions of the test. He lied his ass off, but he passed. :)

        I

    • Re:remorse (Score:3, Informative)

      by Anonymous Coward

      Most polygraphs work on the idea of remorseful feelings the subject
      will have if they report a lie in response to a question.

      Sort of. This is how they work:

      There are null questions, 'control' questions, and pertinant questions which are asked by a tester who also attempts to spook/convince the victim that their 'high tech' equipment actually gives them the ability to tell if someone is lying. No equipment can tell if you are lying short of a PET scan which they can't afford to give you. Even a PE

  • by ForestGrump (644805) on Tuesday October 26, 2004 @08:55AM (#10629929) Homepage Journal
    ok, this is a little OT, but i thought it was fascinating enough that i'll post it anyway.

    So a few weeks ago, I was driving back to school late at night and was listening to Art Bell (yes, its full of wackos but it's entertaining. Been listening since 7th grade)

    Anyway, there was this guest on about polygraphs and plants, yogurt bacteria, eggs, food, etc.

    Basically the guest said that if you hook up a polygraph to various "living" things, you can get some sort of reading off of them. If you put stress on/around the thing being monitored, it will react.

    For example, if you hook up a polygraph to an egg, and have a dozen other eggs around it. If you take one of the eggs and put it in boiling water, the egg hooked up to the polygraph machine will go crazy.

    With plants and yogurt. If you hook up a polygraph to a plant, and have a cup of "live" yogurt beside it. If the yogurt is disturbed (such as stirring up the fruit in the yogurt). This will kill the live bacteria in the yogurt and the plant would react.

    Lastly, the guest said that you can't (for the most part) beat a polygraph with anything mjaor (such as if you murdered someone). Why? Because you conscience would get the best of you. The one exception is if you life was in danger. (he didn't elaborate much on what that meant)

    And lastly, a link to the show [coasttocoastam.com]
    • by ForestGrump (644805) on Tuesday October 26, 2004 @08:57AM (#10629937) Homepage Journal
      oh look, antipolygraph.org has a thread on that show.
      http://antipolygraph.org/cgi-bin/forums/YaBB.pl?bo ard=off;action=display;num=1096866906 [antipolygraph.org]
    • Lastly, the guest said that you can't (for the most part) beat a polygraph with anything mjaor (such as if you murdered someone). Why? Because you conscience would get the best of you. The one exception is if you life was in danger. (he didn't elaborate much on what that meant)

      If you are the type of person who can murder someone, isn't there a higher probability that you don't have much of a conscience? Yes, I know, it's still the case that most murderers will have done it for a stupid reason and feel wr

    • conscience would get the best of you eh? Obviously he's never heard of people without consciences. He's also never heard of people like me who have consciences but can act against them at will providing I can prove to myself that what I'm doing is correct despite feeling it is wrong.
      • "He's also never heard of people like me who have consciences but can act against them at will providing I can prove to myself that what I'm doing is correct despite feeling it is wrong. "

        This is totally off topic, but what standard are you using when proving to yourself that your conscience is wrong? I'm sure the philosopher Hume would have liked to know, as this is believed to be impossible in moral questions :-)

        But I don't think you are wrong when you say you do that. Millions of people do it all the t
    • What exactly does it mean to hook a polygraph up to a plant? A polygraph usually includes a heart rate monitor, a respiration monitor, a blood pressure cuff, and a galvanic skin response monitor. I suppose I could pretend that plants sweat in response to stress, but what is the heart rate monitor going to do? And where do you hook up the respiration sensor (which counts chest motion, not gas composition)? Can you have systolic pressure in something which doesn't have a heart?

      In other words, not only is
      • The guy who was on the Art Bell show is Cleve Backster [backster.net], a living legend in the polygraph community. He is the "father" of the CIA's polyraph program (c. 1948), and he later (c. 1960) came up with the concept of numerical scoring of polygraph charts, which made it possible for different polygraphers to generally reach the same conclusions in scoring polygraph charts.

        He attached only the finger electrodes of the polygraph instrument to plants. For more on his ideas about plants (no one has been reproduce hi

        • George,
          Cleve seems to have quite an impressive background. However, is this guy serious about plants and poly, or is he just someone who "lost his mind" and is like my 85 year old grandfather who used to be an accountant? thinks he can still add numbers (but his math is 90% wrong these days)

          Grump.
          • As far as I know, there is nothing wrong with Backster's mental faculties. I listened to a five-minute excerpt from his interview with Art Bell, and he seemed quite lucid.

            While Backster appears to sincerely believe what he says about plant "perception," it also seems that his plant experiments were poorly designed, which would help to explain why no one else has been able to reproduce his findings.

    • With plants and yogurt. If you hook up a polygraph to a plant, and have a cup of "live" yogurt beside it. If the yogurt is disturbed (such as stirring up the fruit in the yogurt). This will kill the live bacteria in the yogurt and the plant would react.

      I'm not sure, but I would say the plant was lying. The bacteria on the other hand was just making things difficult by revolting against the stirred fruit.
  • by PIPBoy3000 (619296) on Tuesday October 26, 2004 @09:04AM (#10629978)
    There was a recent study [scotsman.com] where a small number of people were able to detect lies with a nearly 100% accuracy. To me, this is far more impressive than a polygraph's results.
    • by Anonymous Coward
      this would suggest that the polygraph is really a sort of rosarch test- it doesnt matter what the thing does, its the examiner looking the subject in the eye where the real test is.

      It also seems to me that if the myth of the polygraph is debunked and the subject doesnt believe in it, he can just look the examiner in the eye without fear and lie to him like normal.
    • There was a recent study where a small number of people were able to detect lies with a nearly 100% accuracy. To me, this is far more impressive than a polygraph's results.

      The problem with such a skill, is it is going to be damned well inadmissable in court.

      You will never (I hope) see a day where someone can simply say This person is lying, and I offer my level two wizard to prove it.

      At least with a polygraph they can holt up charts and the like and say "This is why we think this man is lying", and som

    • Actually, there called "mothers" and they're a much larger group than previously thought.
    • Dr. Oliver Sacks, in his fascinating "The Man Who Mistook His Wife for a Hat", related a case of a group of aphasia and agnosia patients in a group home laughing out during a speech by Ronald Reagan...when Sacks asked them what was so humorous, they told him that Reagan was blatantly lying. Further testing by Sacks led him to believe that these individuals were indeed endowed by their disability with the capacity to distinguish dishonest people.
  • by Free_Trial_Thinking (818686) on Tuesday October 26, 2004 @09:19AM (#10630078)
    I always wondered how a lie detector would respond to the statement:

    "I am lying." or "This sentence is a lie."

    It's not true or false. ...maybe it would break...

  • Polygraphs are bunk (Score:5, Informative)

    by BenEnglishAtHome (449670) on Tuesday October 26, 2004 @09:37AM (#10630206)
    I've taken one polygraph in my life. I was 19 and full of that sort of moral superiority that comes from the false certainty of youth. I answered all the questions truthfully, especially the one about whether I'd ever smoked pot. I hadn't and thought anyone who did was a loser. In fact, I felt strongly about the subject.

    Afterward, the guy puts his arm around me and tells me I passed and that one lie that I told about the pot wouldn't be held against me. He patted me on the back and sent me on my may.

    One anomalous response was interpreted as a lie. A faulty technology had convinced a total stranger that I smoked pot when I never had. The report of that session went to my new employer who didn't fire me but did make the report available to another employee who happened to be my sister. To this day, she thinks I've experimented with drugs when I haven't. After all, what's my word balanced against a neat-o cool technology with all those scribbling pens and sensors and stuff, right?

    Polygraphs are bunk. People who make their living in that industry are, by my definition, liars and should be shunned.

    Yes, I know I'm only one data point. But sometimes it only takes one data point to know when a technology has failed and is not trustworthy in broad application.
    • Two data points.

      Your experience almost exactly parallels mine except I didn't get a job at the 7-11 when I "failed" the test.

      Previously, the manager had been keen to have me start and even planned my schedule, but after the required poly, the job offer was rescinded. I was never told the reason but I think it was quite clear.
      • You had to do a polygraph to get a job at a 7-11 ??!?

        I knew the job market was a bit on the slow side these days.. but sheesh!
    • Dude, you sound like such an angry young man.

      Go smoke some pot!!!!!!

    • You say you feel strongly on the subject of the use of drugs. When you were asked this question your body reacted and this was detected.

      Polygraphs pick up body reaction. Sadly to few are used and humans are to complex to truly be able to tell why a person reacts.

      A simple test is a pedophile image. Both a pedo and a normal person would react with an increased heart rate. The pedo because he is excited, the normal person because of revulsion.

      Only when you would start to measure things like blood chemistry

    • I agree with you for the most part. I pretty much think like you do, but recently I've heard things to make me re-evaluate how good polygraphs are.

      My girlfriend is a psycology major, and she's interested in the criminology aspect. She's currently taking a class that discussed this very subject.

      She was talking about the success/failure rate of polygraphs, and I stated the opinion that polygraphs were nothing more than stress/sweat tests.

      She said that is was partially true, but that they look at so many
      • That's not a testament to the accuracy of polygraph tests, it's a testimony to how *horrible* eyewitnesses are at remembering details.
      • Well, yes and no.

        While it's true that the new techniques are better for detecting lies made up on the spot, they still fail against someone who has thought up, "visualized", and/or gone over their story before.

        The brain is complicated, but one thing that's becoming clear is that it's not good at differentiating input sources. Without extensive training, it can be unreliable. That's where all the "false memory" stuff comes from and where the pre-visualization "success!" techniques come from. If you visuali
    • by Sigma 7 (266129)

      Afterward, the guy puts his arm around me and tells me I passed and that one lie that I told about the pot wouldn't be held against me. He patted me on the back and sent me on my may.

      A polygraph test needs is composed of four parts:

      1. Reaction when no question is being asked.
      2. Reaction to a question where you have no reason to lie.
      3. Reaction to a question that where the true answer is embarrasing. For this question, the polygraph is detecting an emotional response rather than a lie (e.g. Have you ever

  • by Jason Ford (635431) on Tuesday October 26, 2004 @09:48AM (#10630274)
    I took three polygraphs as part of a process to obtain a security clearance (no, I didn't get it.) I believe the effectiveness of the polygraph has little to do with the 'technology', and a lot to do with the theater surrounding the examination.

    From Skepdic [skepdic.com]:

    'It doesn't appease me that many defenders of the polygraph know it is junk science but defend its use because many people confess to crimes during interviews done before or after being given the test. The machine may not be able to detect lies accurately but, as Richard Nixon said, "it scares the hell out of people." The end justifies the means.'
  • by Kronovohr (145646) <kronovohr@nOsPam.gmail.com> on Tuesday October 26, 2004 @11:21AM (#10631111) Homepage

    is in Scientology. Those individuals train for years to defeat a lie detector, even if they're not ready for it. The e-meter basically is a lie detector (it's a little hyper-sensitive on any reaction, as is shown from their "rock slam" of the needle bouncing like mad since they don't use the reduced bounce meters) that they train against for years to get to where nothing they say or do will carry a reaction (i.e. "floating").

    Naturally, as was said before, you can defeat most polygraph tests with 30 minutes of training, or using the ability to answer the "wrong" question with the right answer for what they're asking you.

    • KGB and few other east-european agencies were training their high-profile spies to beat lie detector since mid 50s. They have them hooked on a lie detector and trained them to have "embarassed" response on an emotionaly neutral question. This way the baseline (neutral response) was set high enough to cover a real response. But method took some training and it was not fail-proof (some agents got nervous or tired in a real interrogation, and were less apt at faking their response)
  • On the surface, the press release looks pretty good to me -- the fact of the matter is that only a very small amount of the population has the disicpline, self awareness, and controll to intentionally not get caught lieing on such a test. With access to a machine and a skilled operator and many hours/days/months, etc of practice most people could learn through biofeedback techniques how to do it.

    The real problem (and the reason why it is generally inadmissible in court) is that the polygraph measures phys

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