Plus, credibility of the witness is the very thing that the jury is to assess. They are to determine if they believe a witness, in whole or in part.
If the polygraph operator can assess truth or lies, then why have a jury?
If I can return to detectives using a photocopier as a lie detector for a moment. This was portrayed in the TV series Homicide: Life on the Street.
The TV show was based on the factual book Homicide: A Year On The Killing Streets by David Simon. Sadly I haven’t read the book so although the TV show incorporated many elements from real life I don’t know if the photocopier was one of them.
TCMF-2L
It also occurs to me that operator bias may play an interesting part - if the polygraph operator cannot point to graph results and show “see, he’s lying” then if they think the prosecution wants (what else?) a guilty determination, they may instead of saying “innocent” say “results not conclusive”.
In all those stats, it’s surprising that they quote accuracy for innocent or guilty and not a significant number of “inconclusive” - implying the results are always determinant one way or the other. Did they discard the inconclusive results from the tests?
Penn Jillette’s advise is to just clinch your anus.
Then again, this is the Trickster talking–and he might just really LIKE clenching his arse!
First Hand Experience
I worked for a few years for a small company that dealt in medical sensors and related software. As the lowest ranking employee, I was often hooked up to EKG, photoplathysmograph, pneumatrodes etc to teach clients how to attach sensors and electrodes, how to work the software and how to properly interpret data.
Polygraphs are good (very good in fact) at measuring stress levels IF AND ONLY IF the subject is not trying to conceal the stress or alter the readings. Otherwise, they are worthless at best.
we’ve had this technology for how long now? Isn’t the fact that it hasn’t been found admissible in court in all that time rather telling?
ISTR some instance or two involving training canines to identify when people are lying. I suspect that would probably be more effective and accurate than any physiology analyzer.
Or step your big toes down on tacks you have taped inside your shoes when you answer regardless of if you are telling the truth or lying. This supposedly makes your stress level consistent throughout the process and is one reason why some polygraph administrators have the subject remove their shoes.
I have done research on the subject and know 2 fellows that administrated polygraph tests during their careers, one was a private investigator the other was a federal agent.
I have come to the conclusion that polygraphs are indeed as accurate or even slightly more so than flipping a coin.
My limited understanding is you are asked control questions about obvious things like where you live. Then the resistance measured by electrodes is compared to that, while asking if you have ever exceeded the speed limit, and whether you were driving the getaway car while the bank was being robbed. Maybe a functional MRI might show something of actual meaning. Otherwise, you’d probably be better off just showing the facial reactions in slow motion?
Exactly.
One FBI Polygraph expert confided to me, that they are mostly used to get a confession. They get the perp to tell a minor lie- anything, not important. Then there is the the nut f the matter. So the operator points at a spike, and says “I asked you if you had ever committed a crime, and you said NO, and the lie detector shows you are lying!” The perp knows that is a lie. Then the operators points at more spikes (it doesn’t matter where they are) and says “And when you said you didn’t commit the robbery, it also shows you lied!!” The perp confesses. It is just another scam/lie the police use. And sure, the investigator is already sure the perp did it, so the “lie detector” wins again. Usually, the investigator is right to start with. But not always!
Now, yes, a good operator can tell the subject is nervous. But if you were arrested and questioned, wouldn’t you be nervous?
The guy I talked to was under no illusion at all. His only justification was that evident nervousness can sometimes lead to further investigation.
Because that is just “probable cause” - the drug dog is not evidence you are guilty. The drugs they find are. If they find no drugs, you are let go. But the handlers can see signs you are a user, it is fairly obvious. Couriers are also often obvious, if they are not pros. The Courts are pretty lenient on probable cause, much less so on evidence allowed in court. (the dog is allowed only as evidence of “probable cause”. )
My WAG is that it happened- once.
You can cross examine a witness, and even investigate them… if the suspect has the funds.
It wouldn’t matter. There is no reason to believe that lies can be detected by the measurement of any bodily functions. That idea was originated by inventors of lie detector machines.
I’d prefer a polygraph to the alternative:
Witch swimming was the practice of tying up and dunking the accused into a body of water to determine whether they sink or float. Sinking to the bottom indicated that the accused was innocent while floating indicated a guilty verdict. (Kittredge, p. 232.)Feb 8, 2022
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Swimming a Witch: Evidence in 17th-century English …
Is this the source of your username?
I’m not defending this horrible practice, but weren’t accused witches “usually” pulled up from the body of water if they sunk before they could properly drown?
Still doesn’t make the practice any less messed up.
There is quite a bit of evidence that a polygraph is really not useful, in fact a former cop, Doug Williams, advocated it against it link. Additionally the American Psychological Association also came out as saying that they don’t really detect lies cite. So it is a a good thing that they are not used to in a court of law since they don’t really prove anything.
As an aside, the whole, photocopy machine or some similar contraption to get people to believe that they are undergoing a polygraph test was also used in an episode of The Wire.
//i\\
Sorry, I think the science shows that lie detector machines are useless. I did not mean to imply otherwise. Science may, however, show lies can be detected in other ways with more accuracy (possibly functional MRI or detailed facial muscle analysis - this is not my expertise).
However, to be useful in court both the sensitivity and sensitivity must be high. The old tests, according to knowledgeable people here, are basically guessing. And even experienced people like officers and lawyers are reportedly pretty bad at detecting skilled liars. I wonder if deaf people, or other populations, are better at it?
I read one study years ago that indicated the best lie detectors for kids under 12 was … moms.
There’s always some possibility. Do you think you would have considered that possibility if not for the myth imbued in our culture that some such method existed? Lie detectors were made to detect something not known to exist. I think that’s a pretty damn clever scam myself.
I think you forgot to change a word.
You’re just not sensitive to the difference