# Stop the Lies! **URL:** \ **Category:** Great Debates\ **Created:** [May 29, 2000, 5:12am UTC](https://boards.straightdope.com/t/stop-the-lies/20783 "2000-05-29T05:12:42Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![zuma](https://avatars.discourse-cdn.com/v4/letter/z/e9c0ed/32.png) [@zuma](https://boards.straightdope.com/u/zuma)\ **Post date:** [May 30, 2000, 9:56am UTC](https://boards.straightdope.com/t/stop-the-lies/20783/21 "2000-05-30T09:56:22Z")
> [@](#): > > \*\* > Anyone else remember when Secretary of State George Shultz said he’d resign from Reagan’s cabinet before he would take a lie detector test? > > \*\* Hrm… my recollection was that he said he’d resign before taking a drug test. I think Reagan had proposed drug testing for all, or a large number of, government employees. ---
**Author:** ![AHunter3](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ahunter3/32/368_2.png) [@AHunter3](https://boards.straightdope.com/u/AHunter3)\ **Post date:** [May 30, 2000, 2:21pm UTC](https://boards.straightdope.com/t/stop-the-lies/20783/22 "2000-05-30T14:21:48Z")
From the depths of my cobwebby memory banks, I seem to recall an alternative to the polygraph called the Voice Stress Analyzer, or VSA, which was supposed to be far more accurate. Was that hype that did not withstand closer examination, or what? If they work, why don’t we hear about them any more? ---
**Author:** ![hardcore](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@hardcore](https://boards.straightdope.com/u/hardcore)\ **Post date:** [May 30, 2000, 6:49pm UTC](https://boards.straightdope.com/t/stop-the-lies/20783/23 "2000-05-30T18:49:04Z")
Read [this excerpt](http://www.skepdic.com/refuge/2good.html) from the Skeptic’s Dictionary. It was definitely hype, as the the VSA is no more (or less) accurate than the polygraph. Both devices are a fraud. ---
**Author:** ![Devil\_In\_Disguise](https://avatars.discourse-cdn.com/v4/letter/d/5f8ce5/32.png) [@Devil\_In\_Disguise](https://boards.straightdope.com/u/Devil_In_Disguise)\ **Post date:** [May 30, 2000, 9:30pm UTC](https://boards.straightdope.com/t/stop-the-lies/20783/24 "2000-05-30T21:30:02Z")
I was asked in a polygraph whether I had smoked pot in the last 5 years. Well I hadn’t smoked it for close to 10 years and even then only in experimentation. But the whole subject made me extremely uncomfortable to talk about and the examiner noted I didn’t do well on the question. He didn’t say I was lying but he inferred I had a problem and I was glad I accepted another job and didn’t have to face the interviewer who sent me to get the polygraph again because I don’t know if he would have called me a liar or not. I will never take a polygraph again. They may detect emotional variations, but I don’t think they can specifically tell when someone is lying. ---
**Author:** ![2nd\_Law](https://avatars.discourse-cdn.com/v4/letter/2/f475e1/32.png) [@2nd\_Law](https://boards.straightdope.com/u/2nd_Law)\ **Post date:** [May 31, 2000, 1:12am UTC](https://boards.straightdope.com/t/stop-the-lies/20783/25 "2000-05-31T01:12:56Z")
> [@](#): > > \*\* > > > [@](#): > > > > \*\* > > Anyone else remember when Secretary of State George Shultz said he’d resign from Reagan’s cabinet before he would take a lie detector test? > > > > \*\* > > Hrm… my recollection was that he said he’d resign before taking a drug test. I think Reagan had proposed drug testing for all, or a large number of, government employees. > > \*\* No, it was lie detector. Apparently there was some kind of a flap about leaks to the press and Reagan said something about subjecting members of his staff to lie detector tests to find out who was leaking. ---
**Author:** ![The\_Ryan](https://avatars.discourse-cdn.com/v4/letter/t/7feea3/32.png) [@The\_Ryan](https://boards.straightdope.com/u/The_Ryan)\ **Post date:** [June 2, 2000, 5:47am UTC](https://boards.straightdope.com/t/stop-the-lies/20783/26 "2000-06-02T05:47:44Z")
> [@](#): > > \*\* > **The Ryan** > > > [@](#): > > > > It is well established that there is a positive correlation between a polygraph machine saying that somone is lying and that person actually lying. The statement “These devices likely have the same effectiveness in determining trustworthiness” is ignorance at best. > > Please assume I have actually done some research prior to posting. > \*\* I try to assume as little as possible. I have no intention of changing that policy simply because you ask me to. You say that everything I have ever read about polygraph tests is false, and what do you have to defend your position? Thorough scientific evidence? No, of course not! I’m supposed to just take your word for it! If we’re going to be asking each other to make assumptions, here’s one I’d like you to make: please assume that I am not a complete idiot who will believe anything you say. > [@](#): > > **I suggest you investigate the links JonF provided above to realize that most scientists dispute the legitimacy of polygraphs.** Can you find anything in those links which disputes my claim that 1 - beta \> alpha ? Yes, scientists disagree about _how_ effective polygraph tests are, but that doesn’t mean that they disagree about _whether_ they are effective. > [@](#): > > **Calling me ignorant _“at best”_ about a topic I initiated** What does the fact that you started the thread have to do with it? What am I supposed to say? “Gee, if Hardcore started a thread on this, he must know everything there is to know about it”? > [@](#): > > **indicates you either dismiss the conflicting evidence,** _What_ conflicting evidence? > [@](#): > > **are unaware of it,** Seeing as how you haven’t presented any evidence, I guess it is accurate to say that I am unaware of it. > [@](#): > > \*\*or merely wish to depict your _ **insolence** _ It’s always nice to have a discussion with someone who can interpret disagreement as “insolence” :rolleyes:. ---
**Author:** ![tracer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tracer/32/20578_2.png) [@tracer](https://boards.straightdope.com/u/tracer)\ **Post date:** [June 3, 2000, 1:13am UTC](https://boards.straightdope.com/t/stop-the-lies/20783/27 "2000-06-03T01:13:11Z")
hardcore wrote: > [@](#): > > I don’t see how it can be appropriate. Would either of you feel the same if a potential employer were to whip out a magic 8-ball and use it during the interview? **DO NOT QUESTION THE WISDOM OF MAGIC 8-BALL!** ---
**Author:** ![hardcore](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@hardcore](https://boards.straightdope.com/u/hardcore)\ **Post date:** [June 4, 2000, 8:29am UTC](https://boards.straightdope.com/t/stop-the-lies/20783/28 "2000-06-04T08:29:29Z")
**tracer** :D:D I’ll try not to mock Happy Fun Ball either. **The Ryan** > [@](#): > > please assume that I am not a complete idiot who will believe anything you say. I have never made such an assumption, and likely never will. However, I will assume that you haven’t bothered to research the links I mentioned. So I will go through the tedium of pasting portions of it on this page to increase the chances that you might read it. All bolding will be mine. > [@](#): > > Can you find anything in those links which disputes my claim that 1 - beta \> alpha ? Since this sounds greek to me, I will assume you are referencing the subject of this thread – the scientific validity of polygraphs as lie-detectors. Let’s start with a few excerpts from the first link, [The Skeptic’s Dictionary](http://skepdic.com/polygrap.html): > [@](#): > > Psychologists do not think either the CCT or the DLT is scientifically sound… Is there a scientific formula or law which establishes a regular correlation between such physiological changes and lying? No. Is there any scientific evidence that polygraph experts can detect lies using their machine at a significantly better rate than non-experts using other methods? No. > > The ACLU supported the EPPA not only because of the **lack of evidence for the accuracy of the polygraph** , but because of abuses related with its administration, including, but not limited to, the invasion of privacy. > > What is the evidence that the rate of correct identification of lying corroborated by extrinsic evidence is greater than the rate of identification of lying by non-technological means? There isn’t any. The proofs are anecdotal or based on fallacious reasoning such as thinking that a correlation proves a causal connection. I realize you might dismiss the information from The Skeptic’s Dictionary because it is just so, well… _skeptical_. So let’s try the next link provided, from our own government’s Office of Technology Assessment, entitled [Scientific Validity of Polygraph Testing: A Research Review and Evaluation](http://www.fas.org/sgp/othergov/polygraph/ota/index.html) > [@](#): > > In 1965 and again in 1976, the House Government Operations Committee concluded that there was \*\*not adequate evidence to establish the validity of the polygraph. \*\* > > OTA concluded that the **available research evidence does not establish the scientific validity of the polygraph test** for personnel security screening. > > The validity of polygraph examinations to detect deception has long been a controversial issue. … Despite many decades of discussion, no consensus has emerged about the accuracy of polygraph tests. > > OTA recognizes that the administration as well as NSA, CIA, and DOD believe that the polygraph is a useful screening tool. However, OTA concluded that the **available research evidence does not establish the scientific validity of the polygraph** for this purpose. > > It appears that NSA (and possibly CIA) use the polygraph not to determine deception or truthfulness per se, but as a technique of interrogation to encourage admissions. > > Claims of usefulness, however, are often dependent on information (e.g., confessions and admissions) obtained before or after the actual test, and on its perceived value as a deterrent. > > However, there is very little research or scientific evidence to establish polygraph test validity in large-scale screening as part of unauthorized disclosure investigations, or in personnel security screening situations, whether they be preemployment, preclearance, periodic or aperiodic, random, or “dragnet.” Just in case you think the government is in on the conspiracy, I’ll go to the next link offered, [Psychologists debate merits of the polygraph](http://www.apa.org/monitor/jun98/lie.html): > [@](#): > > Some scientists say the so called lie-detector test is about as accurate as a palm reading. > > In the majority opinion, Justice Clarence Thomas states that military rules of evidence call for only reliable evidence to be introduced in trial and that **scientists and legal experts have never agreed that polygraph results are reliable.** > > To illustrate the disparity, Thomas cited psychologists W.G. Iacono, PhD, and David Lykken, PhD, who showed the accuracy rate of polygraphs to be barely better than 50 percent. To be thorough, I also include this from the aforementioned [Statement of Steven Aftergood](http://www.fas.org/sgp/othergov/polygraph/aftergood.html#skep): > [@](#): > > The validity of polygraph testing as a means of detecting deception is the underlying question that cannot be escaped. Only the answer to this question can determine whether, how, and to what extent the polygraph is used. > > Unfortunately, as the Joint Security Commission reported in 1994, “ **the scientific validity of the polygraph is yet to be established.** ” > > Without established validity, the process lacks full integrity and appears more like trickery because information is obtained from subjects under the pretense that it is in their best interest to be forthright since false answers will be discovered. > > Without an established scientific basis for the application of the polygraph, the controversy over its use will continue to fester. Now all of the above was included in the links **JonF** provided and I mentioned to you. Yet you replied to me with this: > [@](#): > > What conflicting evidence? Seeing as how you haven’t presented any evidence, I guess it is accurate to say that I am unaware of it. Hmmm… are you now aware of it? Or do you simply proclaim everyone cited above to be “ignorant at best”? Always one to try and provide more than necessary, I present further evidence of the polygraph’s fallibility. To determine the scientific community consensus, see [The Validity of the Lie Detector: Two Surveys of Scientific Opinion](http://www.nopolygraph.com/academia.htm) > [@](#): > > …we conducted mail surveys to obtain the opinions of 2 groups of scientists from relevant disciplines: members of the Society for Psychophysiological Research and Fellows of the American Psychological Association’s Division 1 (General Psychology). Survey return rates were high (91% and 74%, respectively). Most of the respondents believed that **polygraphic lie detection is not theoretically sound** Since the FBI likes to use the damn thing, I thought this [statement](http://www.nopolygraph.com/) from the Head of the FBI Polygraph Unit, Special Agent James Murphy would be appropriate. > [@](#): > > The FBI uses the polygraph as an investigative tool and cautions that the results should not be relied upon to the exclusion of other evidence or knowledge obtained during the course of an investigation. This policy is based upon the fact that, a) **the polygraph technique has not reached a level of acceptability within the relevant scientific community** , b) scientific research has not been able to establish the true validity of polygraph testing in criminal applications, c) there is a lack of standardization within the polygraph community for training and for conducting polygraph examinations. A recent article in Salon (admittedly not a scientific journal) had these tidbits from [The truth about the polygraph](http://www.salon.com/health/feature/2000/03/02/polygraph/index.html) > [@](#): > > The House of Commons’ employment committee, “concerned at the Government’s apparent faith in the polygraph test procedures and its implications,” held an inquiry, at which the **British Psychological Society, among others, roundly denounced polygraphs** , and the scheme was dropped. > > Manuel Garcia, a physicist at the Lawrence Livermore Nuclear Laboratory (LLNL) compares it to **phrenology**. **Edward Teller** , director emeritus of the LLNL, put it more tactfully in a letter to DOE Secretary Bill Richardson, calling it “a clumsy and imperfect tool” that produces “ **rather dubious evidence.** ” Please tell me you do remember Edward Teller. For additional statements from scientists, I now turn to a 1983 Federal study of polygraph accuracy, where the author of the study, Brandeis University psychologist Leonard Saxe, PhD, [stated the following](http://www.stopolygraph.com/polygraph/frames_toc.htm) about the polygraph > [@](#): > > **It doesn’t work. It’s not accurate** , and can lead to what are called false positives, finding people untruthful when in fact they are truthful, and the opposite. Likewise, in the [Opening Statement](http://www.stopolygraph.com/polygraph/testimony.htm) of Dr. Drew C. Richardson, FBI Laboratory, before the United States Senate, he had this to say about polygraphs: > [@](#): > > **It is completely without any theoretical foundation and has absolutely no validity.** Although there is disagreement amongst scientists about the use of polygraph testing in criminal matters, there is almost universal agreement that polygraph screening is completely invalid and should be stopped. As one of my colleagues frequently says, the diagnostic value of this type of testing is no more than that of astrology or tea-leaf reading. An article from Al Seckel at CalTech entitled [Pinocchio Science: The Truth About The Polygraph](http://www.klab.caltech.edu/~seckel/Polygraph.html) states > [@](#): > > Moreover, polygraph theory holds that deception produces distinctive physiological changes that characterize lying and only lying. This notion has no empirical support. Quite the contrary: **lying produces no known distinctive pattern of physiological activity.** > > The internationally respected scientific journal Nature published its conclusions last year. Their aggregated findings were based on the polygraph charts of 207 criminal suspects, which 14 polygraphers scored independently. On the average, **they erroneously diagnosed 43% of innocent suspects as deceptive.** Such errors, called false positives, ranged as high as 50%. While John J. Furedy, Ph.D., Professor of Psychology at the University of Toronto [simply states](http://www.fas.org/sgp/othergov/polygraph/furedy.html): > [@](#): > > Once you use the polygraph, you have given implicit assent to **a procedure which has no validity or reliability.** Now, you might be able to uncover something by Raskin or Honts to support your viewpoint. Yet in the midst of this veritable mountain of opposing data, you assert > [@](#): > > Yes, scientists disagree about how effective polygraph tests are, but that doesn’t mean that they disagree about whether they are effective. I’m sorry, but in light of the evidence above, I have to conclude that it is you who are “ **ignorant at best** ” of the current scientific status of polygraphs. ---
**Author:** ![Stratocaster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stratocaster/32/16393_2.png) [@Stratocaster](https://boards.straightdope.com/u/Stratocaster)\ **Post date:** [June 4, 2000, 12:31pm UTC](https://boards.straightdope.com/t/stop-the-lies/20783/29 "2000-06-04T12:31:29Z")
Hardcore, I just don’t get your point here. Does this thing work or not? Try to get off the fence in your next post. ---
**Author:** ![JonF](https://avatars.discourse-cdn.com/v4/letter/j/cab0a1/32.png) [@JonF](https://boards.straightdope.com/u/JonF)\ **Post date:** [June 4, 2000, 1:02pm UTC](https://boards.straightdope.com/t/stop-the-lies/20783/30 "2000-06-04T13:02:39Z")
Thanks. **hardcore** ; I considered going through the process that you went through, but decided I didn’t have time. Looks as if you did it more thoroughtly than I would have. ---
**Author:** ![hawthorne](https://avatars.discourse-cdn.com/v4/letter/h/c89c15/32.png) [@hawthorne](https://boards.straightdope.com/u/hawthorne)\ **Post date:** [June 4, 2000, 4:14pm UTC](https://boards.straightdope.com/t/stop-the-lies/20783/31 "2000-06-04T16:14:29Z")
So as an employer, you _should_ ask people to take polygraph tests. If you are looking for intelligent well educated people, hire the ones who refuse. If you are looking for sheep, hire the ones who take it. 😉 picmr ---
**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\ **Post date:** [June 4, 2000, 4:40pm UTC](https://boards.straightdope.com/t/stop-the-lies/20783/32 "2000-06-04T16:40:49Z")
Just a late addition. This last week “Good Morning Amerika” reported the 95% accuracy quote as an absolute fact. So now 15 million or so additional people will believe it. ---
**Author:** ![The\_Ryan](https://avatars.discourse-cdn.com/v4/letter/t/7feea3/32.png) [@The\_Ryan](https://boards.straightdope.com/u/The_Ryan)\ **Post date:** [June 4, 2000, 6:42pm UTC](https://boards.straightdope.com/t/stop-the-lies/20783/33 "2000-06-04T18:42:26Z")
> [@](#): > > > [@](#): > > > > Can you find anything in those links which disputes my claim that 1 - beta \> alpha ? > > Since this sounds greek to me, It is standard statistical notation. Now, let’s see what “evidence” you have: > [@](#): > > The proofs are anecdotal or based on fallacious reasoning such as thinking that a correlation proves a causal connection. Seeing as how polygraph tests are not concerned at all with causation, but only with correlation, that makes no sense. > [@](#): > > Some scientists say the so called lie-detector test is about as accurate as a palm reading. So? Do they have evidence for this statement? > [@](#): > > To illustrate the disparity, Thomas cited psychologists W.G. Iacono, PhD, and David Lykken, PhD, who showed the accuracy rate of polygraphs to be barely better than 50 percent. Sounds better than random to me. > [@](#): > > Hmmm… are you now aware of it [the evidence]? No, I still have yet to see any evidence that the polygraph test does not work. All I see is a bunch of quotes from people that haven’t seen any evidence that it works. Ansence of evidence is not evidence of absence. > [@](#): > > The FBI uses the polygraph as an investigative tool and cautions that the results should not be relied upon to the exclusion of other evidence or knowledge obtained during the course of an investigation. I agree with this policy. > [@](#): > > It doesn’t work. It’s not accurate\*\*, and can lead to what are called false positives, finding people untruthful when in fact they are truthful, and the opposite. The fact that it leads to false positives hardly means that it doesn’t work. Just to make my position clear: I don’t think that polygraphs are perfect or even good instruments for determining whether someone is telling the truth. But given a choice between a Magic Eight Ball test and a polygraph test, I’d definitely go for the polygraph test. ---
**Author:** ![tracer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tracer/32/20578_2.png) [@tracer](https://boards.straightdope.com/u/tracer)\ **Post date:** [June 4, 2000, 7:21pm UTC](https://boards.straightdope.com/t/stop-the-lies/20783/34 "2000-06-04T19:21:43Z")
Hey, Ryan, how’d you get your post to change to a Times Roman font near the end there? ---
**Author:** ![JonF](https://avatars.discourse-cdn.com/v4/letter/j/cab0a1/32.png) [@JonF](https://boards.straightdope.com/u/JonF)\ **Post date:** [June 4, 2000, 10:54pm UTC](https://boards.straightdope.com/t/stop-the-lies/20783/35 "2000-06-04T22:54:41Z")
> [@](#): > > No, I still have yet to see any evidence that the polygraph test does not work. All I see is a bunch of quotes from people that haven’t seen any evidence that it works. Ansence of evidence is not evidence of absence. Actaully, you have seen a bunch of quotes from people who have _looked very hard_ for evidence that it works, and found none; but they have found evidence that it does _not_ work. Got any citations for scientific evidence (statistical evidence is acceptable) that it _does_ work? ---
**Author:** ![The\_Ryan](https://avatars.discourse-cdn.com/v4/letter/t/7feea3/32.png) [@The\_Ryan](https://boards.straightdope.com/u/The_Ryan)\ **Post date:** [June 5, 2000, 12:10am UTC](https://boards.straightdope.com/t/stop-the-lies/20783/36 "2000-06-05T00:10:30Z")
Tracer: > [@](#): > > Hey, Ryan, how’d you get your post to change to a Times Roman font near the end there? Doesn’t look like a different font to me. JonF > [@](#): > > Actaully, you have seen a bunch of quotes from people who have looked very hard for evidence that it works, and found none; but they have found evidence that it does not work. “Looked very hard”? What are you talking about? Just what have these scientists done to look for evidence? Have they performed experiments? I haven’t seen any cited. > [@](#): > > Got any citations for scientific evidence (statistical evidence is acceptable) that it does work? No, I don’t. Have I started a thread in GD proclaiming polygraphs to be effective? No, I haven’t. ---
**Author:** ![JonF](https://avatars.discourse-cdn.com/v4/letter/j/cab0a1/32.png) [@JonF](https://boards.straightdope.com/u/JonF)\ **Post date:** [June 5, 2000, 12:29am UTC](https://boards.straightdope.com/t/stop-the-lies/20783/37 "2000-06-05T00:29:34Z")
> [@](#): > > Have I started a thread in GD proclaiming polygraphs to be effective? No, you have not started a thread. In an existing thread you have stated: “It is well established that there is a positive correlation between a polygraph machine saying that somone is lying and that person actually lying. The statement “These devices likely have the same effectiveness in determining trustworthiness” is ignorance at best.” “scientists disagree about how effective polygraph tests are, but that doesn’t mean that they disagree about whether they are effective” You have made claims without any support for those claims. Is there a difference between starting a thread with that assertion or making that assertion somewhere inside a thread? > [@](#): > > Looked very hard"? What are you talking about? Just what have these scientists done to look for evidence? Have they performed experiments? I haven’t seen any cited. I am talking about the references which are available to you just by clicking on the links in previous messages. Some of these are reviews of experiments, some are reviews of the literature of experiments. Many of them include references to reports of the reviewed experiments. The only reason that you haven’t seen any experiments cited is that you have refused to make the effort of clicking your mouse and reading. You want to know just what these scientists have done to lok for evidence? **Read what they’ve written!** You have also refused to provide any references to support your assertion. You made a claim; do you have any support? It’s your claim, it’s your responsibility to support it, especially when evidence has been provided that contradicts your claim. ---
**Author:** ![The\_Ryan](https://avatars.discourse-cdn.com/v4/letter/t/7feea3/32.png) [@The\_Ryan](https://boards.straightdope.com/u/The_Ryan)\ **Post date:** [June 5, 2000, 1:41am UTC](https://boards.straightdope.com/t/stop-the-lies/20783/38 "2000-06-05T01:41:27Z")
> [@](#): > > Is there a difference between starting a thread with that assertion or making that assertion somewhere inside a thread? Yes. I would not start a thread dedicated to an assertion unless I had evidence at hand for that assertion. > [@](#): > > The only reason that you haven’t seen any experiments cited is that you have refused to make the effort of clicking your mouse and reading. I don’t have several hours to spend wafding through those websites. You want to see evidence that polygraph tests are effective? Go to a library. How is that any better? > [@](#): > > It’s your claim, it’s your responsibility to support it, It arose from a claim that hardcore made, a claim that has not been supported. > [@](#): > > especially when evidence has been provided that contradicts your claim. You evidently have a very strange definition of “provided”. ---
**Author:** ![Feynman](https://avatars.discourse-cdn.com/v4/letter/f/2acd7d/32.png) [@Feynman](https://boards.straightdope.com/u/Feynman)\ **Post date:** [June 5, 2000, 3:38am UTC](https://boards.straightdope.com/t/stop-the-lies/20783/39 "2000-06-05T03:38:46Z")
> [@](#): > > Seeing as how polygraph tests are not concerned at all with causation, but only with correlation, that makes no sense. Actually, the evidence that hardcore presents shows there isn’t even much correlation. > [@](#): > > So? Do they have evidence for this statement (that “the so called lie-detector test is about as accurate as a palm reading”)? Harcore cites at least two studies: > [@](#): > > To illustrate the disparity, Thomas cited psychologists W.G. Iacono, PhD, and David Lykken, PhD, who showed the accuracy rate of polygraphs to be barely better than 50 percent. > > The internationally respected scientific journal Nature published its conclusions last year. Their aggregated findings were based on the polygraph charts of 207 criminal suspects, which 14 polygraphers scored independently. On the average, they erroneously diagnosed 43% of innocent suspects as deceptive. Such errors, called false positives, ranged as high as 50%. Just for reference, calling a statement a lie if a coin flips tails will give you about a 50% success rate. > [@](#): > > The fact that it leads to false positives hardly means that it doesn’t work. Actually it _does_. Its results would perhaps be acceptable even if it gave a fairly high percentage of false negatives. But the presence of false _positives_ (indicating that people are lying when they’re telling the truth) is precisely the reason why civil libertarians denounce its use. Given the high (43%) rate of false positives, a truthful person would be a fool to subject himself to the test. A common debating technique is to offer an assertion to criticism. Generally, one should have one’s ducks in a row from day one. Hardcore might be guilty of a little sandbagging. However, the links he provided were on point. I can’t see as how anyone would be able to fairly accuse him of asking you to “go to the library.” When someome makes an assertion, they have the burden of proof. Hardcore seems to have satisfied that burden. It is then up to anyone who wishes to contradict his proof to offer evidence to the contrary. I’ve never had a reason to consider the effectiveness of polygraph tests. Before this thread I had given it almost no thought whatsoever. I admit a small bit of bias. The concept of a “lie-detector” seems a bit far-fetched. But I have seen stranger things proved irrefutably true, so I try to keep an open mind. Based, however, the evidence presented in this thread has begun to persuade me that lie-detectors have little more validity than the Magic 8 Ball. ---
**Author:** ![The\_Ryan](https://avatars.discourse-cdn.com/v4/letter/t/7feea3/32.png) [@The\_Ryan](https://boards.straightdope.com/u/The_Ryan)\ **Post date:** [June 5, 2000, 5:09am UTC](https://boards.straightdope.com/t/stop-the-lies/20783/40 "2000-06-05T05:09:11Z")
> [@](#): > > Actually, the evidence that hardcore presents shows there isn’t even much correlation. Do you know what the word “correlation” means? Have you seen anything that looks like a discussion of correlation? > [@](#): > > To illustrate the disparity, Thomas cited psychologists W.G. Iacono, PhD, and David Lykken, PhD, who showed the accuracy rate of polygraphs to be barely better than 50 percent. Barely better is still better. > [@](#): > > > [@](#): > > > > The fact that it leads to false positives hardly means that it doesn’t work. > > Actually it _does_. So the test for HIV doesn’t work? Drug tests doesn’t work? The justice system doesn’t work? If that’s your defintion of “work”, then no, polygraph tests don’t work. Can you name a test that does work according to your definition? > [@](#): > > Its results would perhaps be acceptable even if it gave a fairly high percentage of false negatives. But the presence of false _positives_ (indicating that people are lying when they’re telling the truth) is precisely the reason why civil libertarians denounce its use. Given the high (43%) rate of false positives, a truthful person would be a fool to subject himself to the test. I never said that the test was _acceptable_ (except in extreme situations), I just said that it was better than a random test. That is, the rate of false positives is less than that true positives. All of the statistics that you quoted gave only one number, but both numbers are important. Tell me something. If you had a choice between a polygragh test and someone just flipping a coin, wouldn’t you prefer the polygraph? Hardcore said that they’re completely equal. _That’s_ what I’m disagreeing with. > [@](#): > > Based, however, the evidence presented in this thread has begun to persuade me that lie-detectors have little more validity than the Magic 8 Ball. Do the rest of you have a different browser or something? Because I have yet to see _any_ evidence. [Previous page](https://boards.straightdope.com/t/stop-the-lies/20783.md?page=1) [Next page](https://boards.straightdope.com/t/stop-the-lies/20783.md?page=3)