Polygraphs- What's the deal?

jskowron

Really Bad at Karaoke
jskowron
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Jun 30, 2005
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The thread on the Mythbusters "feeling plants" and an interview with an police investigator I saw the other day on the news or a true crime show (I can't remebmer) got me thinking about polygraphs. Everything I've ever read about polygraphs (admittedly bent towards the skeptical end of the literature) idneicates that these things are unreliable as a measurement of physiological characteristics of lying. However, the investigator interviewed said something to the effect of "we became suspicious when they refused to take a lie-detector test." This would indicate that the real "test" might be whether or not you sumbit to the polygraph. I have a few questions for any of you in criminology, law, or physiological measurement-

1. Are lie detectors routinely used to identify suspects? (e.g.- those who refuse are more likely than those who accept)
2. Do police, federales, etc. believe that the results of the polygraph accurately identify lies?
3. Is polygraph evidence admissable in court? What about using the fact that someone refused a test as evidence against supporting their guilt? (I'm in the US, but would be interested in legal positions from other countries)
4. Is there any consistent physiological marker for lying?


NO- I'm not looking to commit any crimes. I just like those true crime shows (the ones without psychics) where they go over the cases, investigation, court proceedings, etc. It seems that polygraphs are often a part of the process, but it is never really detailed how they are used and what type of evidence they generate.
 
What polygraph are is a nervousness indicator. If you can lie without becoming nervous, it is useless. If you are naturally nervous, it will give tha same indications of lying. So, no, I don't believe that they are admissible. I can't speak to the "he refused to take the test, he must be guilty" concept, but it probably is how cop's minds work.
 
Personally I think its a tool for intimidating people. When they're interrogating somebody, they'll take anything that can trip you up. Refusing to take the test is going to get interpreted as a lack of cooperation, and any lack of cooperation will make authorities suspicious, but honestly, if the authorities are asking you for a polygraph test, they're already suspicious.
 
Zombie is right - polygraphs work if the victim believes they will work. So cops use it as a way to intimidate. And they get suspicious if you won't take one - but then, cops will often tell you "a honest man has nothing to hide."

They're cops - they're just doing their job. We can't complain if they get a little zealous about it.

On the other hand, courts are supposed to care about objective truth. And gosh, look; the courts don't allow polygraphs.

I know, I know: it's always such a shock when you see an example of the system working.

:D
 
A good friend of mine is an FBI polygrapher. From conversations we've had I can say that the polygraph is an interrogation aid but the most important element is the polygrapher. He establishes a baseline and then uses the polygraph as a guide during the interview. He uses the information from the machine in addition to other behavioral cues to make a determination regarding the subjects responses to the questions he asks. He says they use the polygraph as a guide only. It is not a "lie detector" but it can help them to determine if they are on the right track or help them eliminate someone as a suspect.

Steven
 
I would agree with Foster Zygote. The general feeling in the police ranks is "it's mostly the operator". Unfortunately, if the operator has preconcieved notions...
60 minutes did a test a few years back. They set up a fake camera store, and hired actors to be the employees. They then contacted three different civilian polygraph firms with the same story; "one of our employees is stealing."

The "manager" did not identify the theif, but in each case, the polygraph team was told that they were "suspicious" of employee X. In each case, the polygraph examiners found employee X "deceptive".

There have been numbers of tests along these lines, indicating the unreliability of the exam. Yet, police agencies almost universally use them as part of hiring practice, and often in interrogation.
A new one making the rounds is the "voice stress analysis" test. Not really new, I think this surfaced about 20 years ago. However, it has had a resurgence of popularity, mainly I believe because the criminal element is not familiar with it. They are told by interrogators that it's "infallible".

All of these things are tools meant to apply pressure to the suspect and see how he/she reacts.
 
Bikewer said:
...A new one making the rounds is the "voice stress analysis" test. Not really new, I think this surfaced about 20 years ago...
Click to expand...
Longer ago than that -- try 30 years. I enjoy books about the Kennedy assassination, and recall reading George O'Toole's book The Assassination Tapes back in the 1970s. In it, O'Toole spends a lot of space explaining lie detection technology, leading up to the voice stress evaluation device, which he used on various tapes from the time of the Kennedy assassination, such as (if I recall correctly) recordings of police radio calls. He detected stress in the voices of the police, and concluded they were lying (and therefore part of a conspiracy...)
 
Foster Zygote said:
A good friend of mine is an FBI polygrapher. From conversations we've had I can say that the polygraph is an interrogation aid but the most important element is the polygrapher. He establishes a baseline and then uses the polygraph as a guide during the interview. He uses the information from the machine in addition to other behavioral cues to make a determination regarding the subjects responses to the questions he asks. He says they use the polygraph as a guide only. It is not a "lie detector" but it can help them to determine if they are on the right track or help them eliminate someone as a suspect.

Steven
Click to expand...

Have they ever tested diagnosed cases of Asbergers, ADD, clinical depression etc. in performing these tests? I wonder how well they would fare...
 
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