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Challenging The 'Unbeatable' Polygraph

timothy posted more than 9 years ago | from the scuffle-worth-scuffling dept.

Biotech 101

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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So... (2, Interesting)

Anonymous Coward | more than 9 years ago | (#10629763)

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... (2, Insightful)

George Maschke (699175) | more than 9 years ago | (#10629792)

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... (1, Insightful)

Anonymous Coward | more than 9 years ago | (#10629889)

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... (5, Informative)

George Maschke (699175) | more than 9 years ago | (#10629922)

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 (4, Insightful)

SmallFurryCreature (593017) | more than 9 years ago | (#10630301)

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 (4, Insightful)

idlethought (558209) | more than 9 years ago | (#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... (2, Insightful)

lobsterGun (415085) | more than 9 years ago | (#10629927)

he alose says that they are only 96% effective when done properly.

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

Re:So... (2, Funny)

Anonymous Coward | more than 9 years ago | (#10630275)

Hey, what's 24 million people between friends?

Re:So... (2, Funny)

Anonymous Coward | more than 9 years ago | (#10630505)

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... (2, Funny)

Anonymous Coward | more than 9 years ago | (#10631049)

Actually, I was using the British definition of "billion", but hey, what's an order of magnitude between friends?

Re:So... (0)

Anonymous Coward | more than 9 years ago | (#10637759)

And hey, what's a little monologue between friends?

Re:So... (1)

spuzzzzzzz (807185) | more than 9 years ago | (#10640147)

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... (2, Insightful)

kalidasa (577403) | more than 9 years ago | (#10629897)

Well, for one, there are those who would like to make polygraphs admissable by law.

Re:So... (4, Insightful)

lobsterGun (415085) | more than 9 years ago | (#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.

Re:So... (1)

macz (797860) | more than 9 years ago | (#10638757)

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.

The problem (1)

warrax_666 (144623) | more than 9 years ago | (#10640291)

is that there is this perception among the general populace that polygraph tests are (nearly) infallible.

Re:So... (3, Interesting)

Evil Schmoo (700378) | more than 9 years ago | (#10630126)

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?

Re:So... (4, Informative)

George Maschke (699175) | more than 9 years ago | (#10630233)

One of the spies I pointed out to Dr. Rovner is Ana Belen Montes, who got a job with DIA at a time when she was already a Cuban agent. She passed her polygraph. The one that's supposed to tell whether or not you're a spy...

I know, isn't it weird? (1)

Ayanami Rei (621112) | more than 9 years ago | (#10631518)

The DoD gave me TS-poly SCI/Counterintel/COMSEY
ME... a foreign cartoon character.

I've got an upcoming briefing with Navy Intelligence brass about my upcoming Yankee White investigation.

Ha ha ha... Suckers.

Re:So... (1)

Paster Of Muppets (787158) | more than 9 years ago | (#10630152)

Ah, but would he make the same statement while undergoing a polygraph test, and if so, what answer would the machine give?

BZZZZZ...

What is your favourite color? (2, Funny)

Awestruckin (824416) | more than 9 years ago | (#10629770)

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..."

Re:What is your favourite color? (0)

Anonymous Coward | more than 9 years ago | (#10629836)

Did you ever watch that Meet My Folks shit? That's the sort of question they asked, the weird ones where you don't always know the answer because you can't recall every event in your life at that instant.

Like, have you ever whacked off 4 times in one 24 hour period. Who the hell can know the answer to that definativly. But you've hesitated, you're confused, so BZZZT, no porking my daughter.

And if they give a quick NO, they pass, when obviously, if they did recollect every little moment in their live they sure as hell couldn't cognate it that fast.

Ya know?

Re:What is your favourite color? (1)

magefile (776388) | more than 9 years ago | (#10630122)

I agree with your point, but I don't think he hesitated 'cuz he didn't know if he'd ever seen porn videos - I think he hesitated because he was stuck either lying or admitting to it.

Re:What is your favourite color? (1)

gardyloo (512791) | more than 9 years ago | (#10634545)

Did you ever watch that Meet My Folks shit? That's the sort of question they asked, the weird ones where you don't always know the answer because you can't recall every event in your life at that instant.

Like, have you ever whacked off 4 times in one 24 hour period. Who the hell can know the answer to that definativly.


That's probably one of the questions, if asked of a guy, that they expect the answer to to be "yes".

Er... Maybe. Anyone? Where did everyone go?

Great news! (1)

Black Parrot (19622) | more than 9 years ago | (#10629779)


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

The problem is... (2, Insightful)

hivemind_mvgc (823238) | more than 9 years ago | (#10629840)

...that they make you take off your tinfoil hat for a polygraph.

Otherwise, I'd be good.

96% accurate? (3, Informative)

hankwang (413283) | more than 9 years ago | (#10629850)

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? (5, Interesting)

George Maschke (699175) | more than 9 years ago | (#10629899)

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? (2, Interesting)

digitalchinky (650880) | more than 9 years ago | (#10631613)

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 not too much effort - unfortunately, they know when you are doing this, so you end up at a nice big round-table meeting to 'discuss' where and how you figured out how to defeat it.
Unpleasant. Black smear on your record. Suspect. Terrorist. Etc.

Are you listening DSD - I know you read this!

Re:96% accurate? (0)

Anonymous Coward | more than 9 years ago | (#10636969)

And for the benefit of those not living in a police state, what is DSD and DSB?

Re:96% accurate? (0)

Anonymous Coward | more than 9 years ago | (#10638915)

Defence Signals Directorate is an Australian intelligence gathering agency with several field sites both domestically and abroad. Notable ones within Australia are ADSCS (Australian Defence Satellite Communications Station) SBRS (Shoal Bay Receiving Station), Pine Gap (Sort of, US funded and run by them for the most part) 7-Sig - Cabarlah - Mobile Intelligence gathering. (Green trucks with odd looking antenna)

Re:96% accurate? (1)

IOOOOOI (588306) | more than 9 years ago | (#10639763)

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.

Re:96% accurate? (1)

Otter (3800) | more than 9 years ago | (#10629988)

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 this under "Dispute Between Two Obsessive Crackpots -- Who Cares?"

Re:96% accurate? (2, Interesting)

George Maschke (699175) | more than 9 years ago | (#10630070)

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.

Re:96% accurate? (1)

Abm0raz (668337) | more than 9 years ago | (#10639295)

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 manipulate these statistics and apply them in misleading ways to screw^H^H^H^H^Hfool the public. Things like cp, cpk, and cpm (different ways to measure machine capability) all use different quality characteristics. Companies will use the one that best fits their needs, even if it's not the most apt for the situation.

-Ab

Base Rate Fallacy (4, Insightful)

hey! (33014) | more than 9 years ago | (#10630054)

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.

Re:Base Rate Fallacy (1)

hankwang (413283) | more than 9 years ago | (#10630247)

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 pseudoscience. I just wanted to point out that it is of dubious value even if you take the proponent's view for granted.

Re:Base Rate Fallacy (0)

Anonymous Coward | more than 9 years ago | (#10630269)

yeah but with this u can ask more than one question

Re:Base Rate Fallacy (1)

bentcd (690786) | more than 9 years ago | (#10647827)

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 ones you dropped were false positives. In this case, the polygraph _did_ give you a 96% chance of not having hired the one terrorist. I'd buy that.

Not that I think for a second that polygraphs have a 96% success rate, but I'm willing to pretend for the sake of argument :-)

My wife is better... (3, Funny)

hummassa (157160) | more than 9 years ago | (#10630080)

She can tell when I'm lying 100% of the time....

Re:My wife is better... (1)

Pseudonym (62607) | more than 9 years ago | (#10636886)

Wives tend to have high false positive rates, though.

Re:My wife is better... (1)

spuzzzzzzz (807185) | more than 9 years ago | (#10640159)

I can tell when you're lying too. A slashdotter in a permanent relationship? BZZZZZT!

Re:96% accurate? (0)

Anonymous Coward | more than 9 years ago | (#10630371)

A +5 can be incomprehensible without context. Quote, please!

That's what the "parent" button is for. Duh.

Re:96% accurate? (1)

hankwang (413283) | more than 9 years ago | (#10630420)

About my sig:

That's what the "parent" button is for. Duh.

Your 10 seconds of doing a copy/paste against 10,000 readers' 2 seconds plus their figuring out which part of the parent you were responding to...

Re:96% accurate? (0)

Anonymous Coward | more than 9 years ago | (#10632982)

Just read at a lower threshold.

Re:96% accurate? (1)

rgmoore (133276) | more than 9 years ago | (#10633010)

"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% of the time. If it means catching 96% of all lies, that could mean that it catches 96% of false statements, or that it can figure out when somebody is lying 96% of the time by asking the same question multiple times and carefully comparing the results. How useful it is depends a great deal on which definition he's using; a system that can flag 96% of false statements is obviously much more useful than one that calls 4% of honest people liars.

Another possible problem is whether they've done tests on enough different populations to know whether those results are generally useful. It's entirely possible that the accuracy rate when testing college students is 96%, but that the rate when testing spies, con-men, and similar trained liars is much lower. If they've validated their method on a different population than the one they're using it on, there's a very good chance that their expected accuracy rate, however defined, is grossly misleading.

Re:96% accurate? (KNOW YOUR STATISTICS!) (2, Informative)

Abm0raz (668337) | more than 9 years ago | (#10635332)

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 actual probability that a 96% accurate polygraph machine would do what you describe (1S + 49 => 2S that are really H) is:

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

This says that it got 47 people right (47H) and 3 wrong (2H + 1S). THAT is what a 96% accuracy means.

Do I believe the doctor's claim that the machine is that accurate? Hell no. I think the doctor that created the claim has a failed understanding of whata statistics actually mean and is giving a stat for something else entirely.

-Ab

Re:96% accurate? (KNOW YOUR STATISTICS!) (1)

Wavicle (181176) | more than 9 years ago | (#10638870)

(.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.

Re:96% accurate? (KNOW YOUR STATISTICS!) (1)

Abm0raz (668337) | more than 9 years ago | (#10639245)

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 48 H's and 2 S's and chances were the 2 S's would be false positives that were really H's. This says that out of the 49 H's, it got 47 right and 2 wrong and of the 1 S it got it wrong. 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.

What the original post got confused is what the 96% meant. It means that the machine gets it RIGHT 96% of the time, not that it returns H 96% of the time. Out of 100 tries, it is EXPECTED that 4 will be wrong, but not necessarily. it would not be unfair to believe 0 would be wrong or that 10 would be wrong. We don't know which type of wrong would occur (false positive nor false negative) because we wouldn't know the true state. The easiest way to avoid this is to administer the test twice. The probability of screwing up twice on the same person is .04 * .04 or .0016 or 16 per 10000 attempts.

Keep in mind, that the actual probability is a confidence interval, (usually 90%, 95%, 99%, or 6sigma). Let's say it's 95%. So the 96% claim is actually saying, "We are 95% certain that the machine will give the correct output 96% of the time." This says that of 100 machines, 95 of them will work at the 96% level. The other 5 ... well, we don't know. They may work better, they may work worse.

All of this is based on the Binomial approximation of the Normal. Vice versa, there is the normal approximation of the binomial. Both are accurate for large enough sample sizes (n>=36). If n36, then correction factors are needed for the bias and the confidence interval increases (which is a bad thing).

-Ab

Re:96% accurate? (KNOW YOUR STATISTICS!) (1)

hankwang (413283) | more than 9 years ago | (#10640089)

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!*2!) = 0.25. Then there is the chance of detecting 48H + 1S(correct) + 1S(false), 49H + 1H(false) + 1S(false), and so on, and the outcome is that you can expect about 2 false positives and 1 correct positive.

The easiest way to avoid this is to administer the test twice.

That is assuming that the chance of a false positive is something in the machine instead of something in the person being examined.

Re:96% accurate? (KNOW YOUR STATISTICS!) (1)

Abm0raz (668337) | more than 9 years ago | (#10640820)

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 false H. You calculated the probability of any 2 False answers (S or H, as long as they were false). Remember, the actual spy's probability is reversed (.96 S, .04 H).

-Ab

Re:96% accurate? (KNOW YOUR STATISTICS!) (1)

Wavicle (181176) | more than 9 years ago | (#10646283)

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 must use combinatorics to arrive at the proper probability.

Re:96% accurate? (KNOW YOUR STATISTICS!) (1)

Wavicle (181176) | more than 9 years ago | (#10642747)

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 you get 1 failure, followed by 47 successes followed by 2 failures, your model does not permit that possibility. You require all 3 failures to come at the end. There are about 20,000 different ways to get 47 successes and 3 failures in any order (50 choose 47 - the binomial aspect for which the distribution is named).

If your argument were a coin, you would say the probability of getting 1 success (say a head) in two tosses is (.5)^1*(.5)^1 = 0.25. But we all know that sample space is { HH, HT, TH, TT } = 0.5 probability of exactly one head. However the probability of getting 1 head followed by 1 tail is indeed (0.5)^1*(0.5)^1.

remorse (3, Interesting)

Anonymous Coward | more than 9 years ago | (#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 (3, Informative)

Anonymous Coward | more than 9 years ago | (#10630488)

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 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. With a little practice many people can learn to control the stress reaction without any physical stimulus needed. By manipulating your stress at appropriate times you can distort the baseline so the polygraph interpreter can't make any solid decisions.

And of course there are people who can just completely eliminate the stress response in their system. Those are often the people who can beat the machine without any training at all.

Re:remorse (1)

Deagol (323173) | more than 9 years ago | (#10631076)

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 always figured there was some truth to that. But it was, after all, only a TV show. :)

Re:remorse (0)

Anonymous Coward | more than 9 years ago | (#10638333)

I'm told that if you don't pass the control group you fail the poly.

Re:remorse (0)

Anonymous Coward | more than 9 years ago | (#10643565)

It's not a matter of making yourself fail the control group. It's a matter of stressing yourself at the appropriate times (for example when you answer truefully). That way there is no differentiation between anything. It's just flat.

Yeah, if you made the graph all wild, that would stick out, but if everything was the same then they got nothing.

Re:remorse (3, Informative)

Anonymous Coward | more than 9 years ago | (#10630699)

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 PET scan may not be able to distinguish from someone making up a story from scratch and someone making up details to fill in gaps in their memory. Making things up to fill in gaps in memory is something we all do.

The tester tells the victim that the null questions are actually 'control' questions. In fact they are merely a ruse. They will ask questions like: what is your name, or what is your date of birth, but the answers and the polygraph data for those questions is discarded.

The real control questions, are questions the tester assumes that the victim will lie about. They want to see what the polygraph data looks like when you do lie. They might ask: "Have you ever told a lie?" Everyone has told a lie. If the victim lies and says: "No, I've never told a lie." then the tester gets his data. If the victim is truthful, and admits to having told a lie, then the tester follows up with something like: "Yes, I know everyone has told a lie about SOMETHING at one time or another, but what I'm interested in is, have you ever told a lie about something important? The tester assumes that the victim has told a lie about something important. If the victim denies lying about something important, then the tester get's their control data, if the victim admits lying about something important, then the tester ups the ante, saying something like: "Yeah, lying is neccessary sometimes, but have you ever told a lie that hurt someone else, or got them in trouble?"

The ante is upped until the the victim denies something. Testers like to pressure victims to lie on the control questions by asking control questions that seem pertinant to the issue at hand. For a job interview, they might ask about stealing from work. Even someone who never filched anything can be coaxed into lying about the five extra minutes they 'stole' on coffee break by a clever questioner.

Then there are the pertinant questions. These are the questions that the tester is trying to determing whether you are lying or not about.

The testers ignore they null questions - they are only part of the ruse. They expect to see the needle move in response to the provocative 'control' questions, and the needle not to move in response to the pertinant questions. This is the ideal "He's telling the truth" result. If the needle moves in response to the controls, and the pertanent questions, then the result is marked as "He's lying."

The third possibility is that the needle never moves for control questions, or for the pertanent questions. If the victim admits to every control question the tester asks, they will have eventually wound up admitting to having sex with their neighbors dog while a busload of fourth graders watched, or some other outrage. If they did not admit to any of the control questions, and the needle didn't move, then the test is inconclusive. They could be a saint, or more likely they have no concience and can lie without making the needle move. Saints and Psychotics are filtered out of the Job Candidate pool in favor of imperfect, morally conflicted people who make mistakes and lie about it, but have at least not lied about any of the 'pertenant questions'. It pays to be what the testers know how to test. As for sainthood, no good deed goes unpunished.

It's possible to get the needle to move by biting your cheek, clenching your anus, stepping on a tack in your shoe, or whatever. IF you can accurately determine which of the questions are controls and which are pertinant, then you can give the testers the results they are looking for. This is not always possible, as the testers like to make the controls look ambiguously pertinant. They COULD, and maybe sometimes DO, ask questions that ARE pertenant as controls. They are worded so as to generate a lie, but they would be things that you wouldn't want to admit to because it would make you look bad in a pertinant way. Unless the question is obviously not pertinant, it's better to not make the needle move. It's also best to deny the control questions early, because the thing they assume you are lying about only gets worse.

Only certain government jobs can legally use polygraphs for employment screening. Who would go through years of schooling to be an FBI agent when a piece of witch doctory could make it all for naught? Seems like a good way to decrease the quality of job applicants and enforce mediocre moral standards in one's workforce. No saints ( or completely amoral ) people allowed. What else is new? Some places use IQ tests to screen out the retards and the geniuses. Some people are too dumb to work here, and others are too smart to work here, even if they want to.

As for criminal investigations, NEVER EVER EVER EVER submit to a lie detector test from the cops. Do not submit to being interrogated either. ( In the US ) your 5th ammendment right gives you the right to have a lawyer present for questioning, and you should always take advantage of that right even if you are innocent.

Submitting to a lie detector test is submitting to an interrogation. How can that help you? It can't. Submitting to a lie detector test is waiving your fifth ammendment rights, which can only ever work to your disadvantage.

REALLY submitting to an interrogation is a DUMB MOVE. The cops generally use the Reid Technique [truthinjustice.org] to badger you into giving the answers they want, even if they aren't true. They think you did it, all they want is for you to admit it so they can close the case. GET A LAWYER.

I wish I could find the link to the Special forces Resistance to Interrogation (R2I) manual. It's basically a manual on HOW TO interrogate someone. It covers Reid, Good Cop/Bad Cop, Pride and Honor Down, Pride and Honor Up and other methods of interrogation.

Polygraphs and plants. (3, Funny)

ForestGrump (644805) | more than 9 years ago | (#10629929)

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]

Re:Polygraphs and plants. (2, Interesting)

squiggleslash (241428) | more than 9 years ago | (#10630003)

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 wrong afterwards, but in sheer percentage terms, you'd expect a higher proportion of those who feel no shame in murder to have committed one than those who do.

This is probably why the "serial killer" in the example passed the detector, for example.

Re:Polygraphs and plants. (1)

Apreche (239272) | more than 9 years ago | (#10630024)

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.

OT:Polygraphs and plants. (1)

Vintermann (400722) | more than 9 years ago | (#10639964)

"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 time, usually by accepting someone elses stated conscience as being more important than their own sense of right and wrong...

Just so we can continue, could you give an example?

Re:Polygraphs and plants. (0)

Anonymous Coward | more than 9 years ago | (#10630144)

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.

So which peer-reviewed publications scientifically describe this "conscience"?

Re:Polygraphs and plants. (1)

ForestGrump (644805) | more than 9 years ago | (#10630171)

none that I know of...heak its Art Bell. Its full of wackos such as Harriet the Witch, Ed Dames and "Remote Viewing", Area 51 employee call in night.

Art Bell is "etnertainment" for a darn good reason.

Re:Polygraphs and plants. (1)

jfengel (409917) | more than 9 years ago | (#10630521)

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 this guy an idiot (you knew that because he was on Art Bell's show), but he's clearly talking out his ass and has never even seen a polygraph, much less hooked one up to anything.

Re:Polygraphs and plants. (1)

George Maschke (699175) | more than 9 years ago | (#10632623)

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 his results in the laboratory), see Backster's other website, PrimaryPerception.com [primaryperception.com] .

Re:Polygraphs and plants. (1)

ForestGrump (644805) | more than 9 years ago | (#10637191)

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.

Re:Polygraphs and plants. (1)

George Maschke (699175) | more than 9 years ago | (#10638649)

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.

Re:Polygraphs and plants. (1)

Midnight Thunder (17205) | more than 9 years ago | (#10631884)

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.

Don't forget human polygraphs (4, Informative)

PIPBoy3000 (619296) | more than 9 years ago | (#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.

Re:Don't forget human polygraphs (1, Insightful)

Anonymous Coward | more than 9 years ago | (#10630032)

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.

Re: Don't forget human polygraphs (2, Insightful)

gstoddart (321705) | more than 9 years ago | (#10631116)

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 someone can refute the underlying science or lack thereof.

Taking some subset of the populace and claiming that they can detect any and all lies and should be therefore allowed to assert in court that someone else is in fact lying sounds completely unsupportable. How do we know he's telling the truth? How do we know he's even a wizard?

It might be a neat trick at parties or if you're a teacher or parent, but I can't see this ever gaining any legal standing in court, because it would be heresay.

Re:Don't forget human polygraphs (2, Funny)

AlexeiMachine (604654) | more than 9 years ago | (#10631749)

Actually, there called "mothers" and they're a much larger group than previously thought.

Re:Don't forget human polygraphs (1)

alleycat0 (232486) | more than 9 years ago | (#10631753)

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.

How about paradoxes? (3, Funny)

Free_Trial_Thinking (818686) | more than 9 years ago | (#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 (5, Informative)

BenEnglishAtHome (449670) | more than 9 years ago | (#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.

Re:Polygraphs are bunk (1)

HardYakka (265884) | more than 9 years ago | (#10630336)

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.

Re:Polygraphs are bunk (0)

Anonymous Coward | more than 9 years ago | (#10630396)

Holy crap, you have to take a polygraph test to work at 7-11?

WTF?! I've never had to do anything like that for any job. In fact, I think I would refuse on the grounds that it's invasion of privacy.

I mean, what the hell are they asking you? A simple drug test would make more sense. I mean, if they're that concerned, just do random drug tests every few months. Sheesh.

Re:Polygraphs are bunk (1)

Poppler (822173) | more than 9 years ago | (#10635364)

A simple drug test would make more sense. I mean, if they're that concerned, just do random drug tests every few months. Sheesh.

I consider that invasion of privacy as well. It's one thing if you're going to be employed as, say, a bus driver, and your drug problem could result in lots of dead people. But for most jobs, shouldn't your performance and your relations with co-workers be the only factors taken into consideration by management? Firing someone because they were intoxicated (not nessecarily on the job) is just going way overboard.

When someone starts showing up to work an hour late, shaking and sweating, and ducks into the bathroom to shoot up, it's time to fire them. If someone wants to smoke a joint or blow a line of coke on their own time, it shouldn't be the employers business. Of coarse I also don't think it should be the federal governments business, so I'm sure some will disagree with me :)

Besides, drug testing is a poor business practice [aclu.org] .

Re:Polygraphs are bunk (1)

DjReagan (143826) | more than 9 years ago | (#10630481)

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!

Re:Polygraphs are bunk (1)

ZosX (517789) | more than 9 years ago | (#10630348)

Dude, you sound like such an angry young man.

Go smoke some pot!!!!!!

Re:Polygraphs are bunk (1)

BenEnglishAtHome (449670) | more than 9 years ago | (#10631327)

No, no, no. I *WAS* an angry young man all those years ago.

Now, I'm just a crotchety old fart. :-)

What might have happened (2, Insightful)

SmallFurryCreature (593017) | more than 9 years ago | (#10630431)

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 and brain activity would you be able to do a true polygraph.

At the moment it is like trying to tell if someone if is lying in an interview by crossing their arms (said to be a typical defensive position). It might just be they are hiding a stain they suddenly spotted, are cold, trying to stop their arms from moving because they are expressive people and been told off about it, just plain nervous about job interviews, trying to hide their beer belly, are just listening to what your saying and really thinking about it.

Polygraphs are a tool, not 100% reliable but an indication for investigators in wich direction they could be looking for more solid evidence.

Those who riducle polygraphs forget one tiny little detail. Most criminals are not smart, prepared, cool blooded and calculated offenders. Just as often as not the polygraph is a bluff wich the criminal will fail just because they know they are guilty and will be found out.

Smart people beating a police polygraph is a total lie. Smart people are never even questioned by the police.

Re:What might have happened (0)

Anonymous Coward | more than 9 years ago | (#10630940)

Smart people are never even questioned by the police.

John Gotti was reported to have a 140 IQ. He just may have been questioned by the police at least once in his life.

Re:Polygraphs are bunk (1)

zeus_tfc (222250) | more than 9 years ago | (#10630474)

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 different clues, that it is becoming harder and harder to fool them.

She also told me that they are working on a lie detector that uses a CAT scan of the brain to show when people are lying. Appearantly different parts of the brain are used when you tell a lie, regardless of what kind of stress you are under.

The real eye opener for me was when she told me what the success rate of a polygraph was when compaired to the credibility of an eye witness. The polygraph was actually right more often than the eye witnesses. I'm sorry I don't have the numbers right now. I'm not the one who took the class.

Anyway, just food for thought.

Now I will use my tremendous powers of precognition to predict what the next joke will be:

My girlfriend is a psy*BZZZZ* No, I mean it.*BZZZZ* No, I HAVE a girlfr*BZZZZ* DAMMIT, GET THIS THING OFF ME!!

Re:Polygraphs are bunk (1)

TilJ (7607) | more than 9 years ago | (#10631533)

That's not a testament to the accuracy of polygraph tests, it's a testimony to how *horrible* eyewitnesses are at remembering details.

Re:Polygraphs are bunk (2, Interesting)

angst_ridden_hipster (23104) | more than 9 years ago | (#10632874)

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 visualize something sufficiently, your brain can become convinced it occured. You can even experience this inadvertently: most people have experienced confusion whether events from dreams were real -- this, of course, is the marginal case; sometimes there is certainty, one way or the other, but whether that certainty reflects reality is another issue.

I don't recall the exact study, but there was one of the conformity analyses where a single test individual was in a room of people who were part of the study. Colors were shown, and everyone would say the name of the color. When they showed a green square, everyone said "purple." Some of the time, the tested individual would go along with the group, and say "purple" the next time the green square was shown.
However, a month after the test, a high percentage of the test individuals *remembered* the square as being purple, even the individuals who had said "green." The active part of the brain (according to CAT or PET scans) was memory recall.

I actually may be conflating two studies here, but I think this was the gist. *ding!* No, really. *ding!* crap. Caught again. When I search I find Moscovici which is sort of like the color part of this, and Hoffman, H.G., Granhag, P. A., See, S. T. K., & Loftus, E. F. (2001), Social influences on reality-monitoring decisions. Memory & Cognition, 29, 394-404, which is about external influencing of memory. I'm sure there's more out there...

Evidently, some pathological liars basically tell themselves stories, and happen to believe them at the time of retelling. Their brain activity is indistinguishable from remembering, even though it's fiction, because they have convinced themselves.

Re:Polygraphs are bunk (0)

Anonymous Coward | more than 9 years ago | (#10632682)

The opposite happened to me: I lied on a polygraph on a very embarassing sexual question.
I passed the polygraphon on all questions. I'd rather not say how I did it, but I did have a plan and it worked.
This saved me from jail time...

Re:Polygraphs are bunk (2, Informative)

Sigma 7 (266129) | more than 9 years ago | (#10632928)

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 imagined what it's like to have sex with your mother?)
4. Reaction to a question where they explicitly expect you to lie.

If any of these aspects is missing, then the test is incomplete. Until then, you cannot tell whether a general statement is truthful or a lie.

The common patterns for this minitest would be #3 being higher then normal, incidating that you are generally truthful, and #3 and #4 indicating that you are generally lying. Other cominations are possible - if reaction to the four tests are the same, then either you are a nervous wreck or extremely relaxed.

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.
That's definatly true. All polygraphs do is measure body reaction to something, which doesn't always indicate truth or a lie. The only true way to tell if a person is lying is if you take a look at the person's brain to examine the memories precisely - a method that's extremely invasive.

false positives (0)

Anonymous Coward | more than 9 years ago | (#10630220)

This does interest me in that I am scheduled to take a "lifestyle" poly sometime in the next two weeks as part of a government screening process. I am not at all worried about the poly cathing me on a lie - I have nothing to hide. I more worry about getting a false positive. What does the research say about faulty readings? I've read a little bit on it, and it seems that the practice is too much and art and not enough a science. Can anyone alay my fears?

Re:false positives (4, Informative)

George Maschke (699175) | more than 9 years ago | (#10630323)

False positive rates(along with overall positive rates) in pre-employment screening situations will vary depending on the agency. The FBI, for example, has an overall polygraph failure rate of about 50%. There is no way of knowing for sure what percentage of those are false positives, but it seems likely that many are. Before 9/11, the FBI's overall pre-employment polygraph failure rate was only about 20%. Did a flood of liars suddenly start applying for the FBI? I don't think so...

Other agencies that administer lifestlye polygraph examinations, such as the CIA and NSA, do not make their polygraph failure rates public, though I suspect that they are somewhat lower than the FBI's.

In the Department of Defense (which uses a counterintelligence-scope polygraph), virtually everyone passes: the only ones who "fail" seem to be those who make what DoD terms "substantive admissions."

For information on what you might expect during your polygraph examination, and tips on how you might protect yourself against the risk of a false positive outcome, see Chapters 3 & 4 of The Lie Behind the Lie Detector [antipolygraph.org] (1 mb PDF).

Re:false positives (5, Interesting)

Jason Ford (635431) | more than 9 years ago | (#10630439)

Sorry, but I can't allay your fears. I failed the lifestyle polygraph three times. The first time, I was told I was lying when I said I had not committed a serious crime; we're talking rape, murder, extortion, and the like. I assure you, I have not. The first polygrapher also berated me for being vegan.

The second time, I was told that I was telling the truth about not committing a serious crime. Well, I gave exactly the same answer as I had during the first polygraph. Did I uncommitt a serious crime? Did I forget I had committed it since my first polygraph?

It seems, however, according to the polygraph at least, that I was stupid enough to experiment with drugs or to sell drugs sometime between my first and second polygraph. For, during the second polygraph, I was 'lying' when I said I had not.

During the third polygraph, where I was told I am very lucky (for it is apparently very rare for someone to be seen a second time, let alone a third; I assure you it is not rare), I was not lying about not using or selling drugs, but the serious crime problem popped up again.

As an experiment during the third polygraph, I lied when I answered one of the questions about all of the information on my form being correct. I took a trip to Canada (my first time leaving the USA) after my second polygraph, but I never amended my form to include it, because I didn't want to have to go through the hassle. The polygrapher wasn't really interested in my answer to this question, apparently.

It was an interesting experience, and gave me some good anecdotes to share with others, but it didn't help anyone figure out if I was telling the truth or not.

Re:false positives (1)

AlexeiMachine (604654) | more than 9 years ago | (#10631844)

>The first polygrapher also berated me for being vegan. What's your beef? He was simply trying to get to the meat of the matter. Don't make poultry excuses, these are very im-pork-tant issues. He probably just smelled something fishy about you. > The polygrapher wasn't really interested... You misspelled "charlatan"...

The Effectiveness of the Polygraph (5, Insightful)

Jason Ford (635431) | more than 9 years ago | (#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.'

The largest bank of proof (3, Insightful)

Kronovohr (145646) | more than 9 years ago | (#10631111)

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.

Re:The largest bank of proof (1)

Muhammar (659468) | more than 9 years ago | (#10633552)

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)

The Truth Machine (0)

Anonymous Coward | more than 9 years ago | (#10632930)

A novel by James Halperin, sets out a fictional account of what would happen to society IF everyone could know if anyone else was telling the truth, or not.

Imagine politics in that brave new world!

What would happen, sir, if you answered the question "So are still beating your wife?"

The real problem with polygraphs (1)

CokeJunky (51666) | more than 9 years ago | (#10634980)

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 physiological responses to stress... It has been shown in the past that it is easy to manipulate the results through the questions (which, of course, a skilled operator would never allow/do ;) and that it is more likely to generate a false negative than a false positive... I.e. It can call people liers who are telling the truth. Furthermore, a pyschopath (in the psychology sense) with no sense of morals or empathy will generally show a very flat response -- they simply don't feel like lieing is some incorrect and their CNS does not respond accordingly. Additionally, some people always look like they are lieing even on the most banal questions like asking a blue eyed person if they have blue eyes, just because you are asking at all. Simply put, if you are ever asked to take one to prove you are innocent, Don't! It's not worth it.

Once again, a self serving piece of propaganda by an operator who wishes to protect their revenue stream by making their work seem valid. This is one of those articles that is basically correct scientifically, but is intended to be misread in a misleading fashion -- just because it is difficult to intentionally beat a lie-detector test, does not mean that the test is meaningful, valid, or reliable.

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