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Are polygraph ("lie-detector") tests reliable?

Are polygraph ("lie-detector") tests reliable?


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Gaztopian

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I believe the test itself works, but the problem with it is that you can learn to deceive it.
 

Southern Dad

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I believe the test works for the most part. Are there those that can deceive it? Yes, but they aren't the average individual. A trained James Bond? Sure no problem lying. I watched a pathological liar take a polygraph. She was positive that she beat that sucker. Right up until her Article 32 hearing. Things went south from there.
 

Beaudreaux

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Are polygraph ("lie-detector") tests reliable?

The machine is undeniably reliable. The human interpretation of the results is less so, but still rather reliable, and still used by the US government when issuing a TS/SCI clearance, investigating government crimes, and other reasons. There are claims by some that the test can be fooled. I've never seen it done, but it may be possible under certain conditions.
 

Skeptic Bob

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I have been polygraphed six times in my life. I spent a few months working in a DoD polygraphy office for a couple months while waiting for my follow-on assignment to open up. Due to my own experience I don't personally think they are reliable. They might be right more often than not, but that is not reliable enough for my comfort. I would never agree to a polygraph if criminally charged with something.

Most people who are caught lying during a polygraph are caught because they get nervous and verbally confess. Or they are caught attempting countermeasures, which are very easy to spot by trained polygraphers.
 

Southern Dad

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I have been polygraphed six times in my life. I spent a few months working in a DoD polygraphy office for a couple months while waiting for my follow-on assignment to open up. Due to my own experience I don't personally think they are reliable. They might be right more often than not, but that is not reliable enough for my comfort. I would never agree to a polygraph if criminally charged with something.

Most people who are caught lying during a polygraph are caught because they get nervous and verbally confess. Or they are caught attempting countermeasures, which are very easy to spot by trained polygraphers.

I've been polygraphed so many that I can't count. I never tried to beat one but I sure saw more than a few try.
 

Black Dog

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They can be fooled if you know how. I have fooled voice stress analyzers and regular lie detectors. This is why they are not allowed in criminal cases as evidence.

It is not easy and I am not going to tell how.
 

Southern Dad

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They can be fooled if you know how. I have fooled voice stress analyzers and regular lie detectors. This is why they are not allowed in criminal cases as evidence.

It is not easy and I am not going to tell how.

But it isn't something the average employee would be able to do.
 

OrphanSlug

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Are polygraph ("lie-detector") tests reliable?

Are they helpful in investigations? Yes.

Are they reliable? No, which is why we have issues with them being used as direct singular evidence in court. When they are admitted odds are it is with qualifying reason.
 

Southern Dad

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Are they helpful in investigations? Yes.

Are they reliable? No, which is why we have issues with them being used as direct singular evidence in court. When they are admitted odds are it is with qualifying reason.

I know they can't be singular evidence but I was on a couple courts martial where they were key evidence. I think the military must have different rules on that one. Maybe states do as well.
 

radcen

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I know they can't be singular evidence but I was on a couple courts martial where they were key evidence. I think the military must have different rules on that one. Maybe states do as well.
I don't believe they are admissible as evidence in any state court, but don't quote me on that. There may be one or two.

I don't know about the military, though it wouldn't surprise me if they are admissible.
 

Captain Adverse

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I have been polygraphed six times in my life. I spent a few months working in a DoD polygraphy office for a couple months while waiting for my follow-on assignment to open up. Due to my own experience I don't personally think they are reliable. They might be right more often than not, but that is not reliable enough for my comfort. I would never agree to a polygraph if criminally charged with something.

Most people who are caught lying during a polygraph are caught because they get nervous and verbally confess. Or they are caught attempting countermeasures, which are very easy to spot by trained polygraphers.

They are NOT reliable.

They are based on a pseudo-scientific notion that human reactions caused by apprehension can allow a person skilled enough in both reading these reactions, and asking leading questions, to result in a reliable evaluation of a person's truthfulness about a specific issue or set of issues.

In the first place, this depends greatly on the so-called "skills" of the person administering the test. Something that varies widely from person to person.

In the second place, people are often apprehensive when facing such a test, because we ALL have something to hide, and a good faith belief that this system is "foolproof" increases such apprehension often resulting it a "deceptive" result.

Finally, this system has never been proven to be foolproof. A pathological liar may or may not pass, the same for a sociopath or psychopath. An honest person may also fail, depending on the circumstances at the time of testing.

I never advised any defendants to take such a test. It almost never helps a case if one passes, but significantly undermines a defense if one fails.
 
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ThoughtEx.

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Question: What happens if you lie on every question during a polygraph test?
 

Southern Dad

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I don't believe they are admissible as evidence in any state court, but don't quote me on that. There may be one or two.

I don't know about the military, though it wouldn't surprise me if they are admissible.

We damn sure took a lot of them when we were in the PRP.
 

radcen

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They are NOT reliable.

They are based on a pseudo-scientific notion that human reactions caused by apprehension can allows a person skilled enough in reading both these reactions and asking leading questions will result in a reliable evaluation to a person's truthfulness in answering questions.

In the first place, this depends greatly on the so-called "skills" of the person administering the test. Something that varies widely from person to person.

In the second place, people are often apprehensive when facing such a test, because we ALL have something to hide, and a good faith belief that this system is "foolproof" increases such apprehension often resulting it a "deceptive" result.

Finally, this system has never been proven to be foolproof. A pathological liar may or may not pass, the same for a sociopath or psychopath. An honest person may also fail, depending on the circumstances at the time of testing.

I never advised any defendants to take such a test. It almost never helps a case if one passes, but significantly undermines a defense if one fails.
I have taken one once in my life... when I applied for a job at 7-11 at age 22. I "failed". The test said I lied about stealing from previous employers. Thing is, I did not lie. I was, however, extremely nervous during the whole process. Needless to say, I didn't get the job. Because of that experience I have done a lot of reading and research on the subject, and my conclusion is that they are NOT reliable. Really no better than a coin-flip.

I also watch a great deal of true crime documentaries and I fully concur with your last paragraph. "Passing" a polygraphs rarely helps a person, but "failing" always hurts. Even if they can't use it in court it solidifies the prosecution's conclusions and they build a case around it. It's a no-win situation, because refusal to take it is obtusely perceived as "hiding something".

Years ago I decided that I would never take one again. If a job requires it, I guess I won't get that job. If I'm being investigated for a crime, whether innocent or not, I will still refuse.
 

Gimmesometruth

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I've supervised a dozen or so exams and taken eight (IIRC) in 40+ years, and in my experience it's a very effective tool in the hands of a skilled operator.
It has been shown time and again that it is unreliable, anecdotes are not evidence of proof.
 

Visbek

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Are polygraph ("lie-detector") tests reliable?
There is no scientific evidence to demonstrate that polygraphs work at all.

It's basically psychological trickery, and an opportunity to grill someone.
 
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