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smashuhleen t1_j284q5f wrote

Lie detector tests are not that accurate, certainly not accurate enough to convict someone with.

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OldTimeyMedicine t1_j28g80r wrote

*Maury Povich has entered the chat

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WinterOkami666 t1_j28oh4f wrote

I was going to make a joke about how we should just have court on TV and air it during the middle of the day as entertainment programming... and then I got depressed when I realized.

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FailureToReason t1_j2857l7 wrote

Short answer: they're not accurate, can be easily fooled, and are basically inadmissible because they have a very weak scientific foundation

What they ARE good for, is manipulation. You swear up and down you didn't kill your wife. Detective asks, 'would you take a polygraph?' And you start sweating bullets. You complete the polygraph, and the polygrapher comes in and tells you 'I know you lied to me.' And maybe they do, or are at least suspicous because of your body language or evidence that contradicts you. But in that moment, under that pressure, people crack.. The cop may have absolutely nothing, and is just fondling in the dark. 'I know you lied on some of these questions.' Next thing you're confessing to a triple homicide that you may never have been caught for.

Edit: body language isn't necrssarily evidence, corrected the phrasing there.

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allthejokesareblue t1_j285z9y wrote

>by body language

Which is also highly inaccurate

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FailureToReason t1_j288njg wrote

Absolutely, but let's not ignore that large part of criminal investigation is 'gut feel' and instinct, and both the polygraph and body language are useful for what they are useful for, but neither is valuable as incriminating evidence. There have been plenty of people who acted guilty as sin but were completely innocent, and plenty of psychopaths who seemed completely innocent until a compelling piece of evidence blew the investigation open.

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LordJadex t1_j28asv5 wrote

It’s almost like they want people confessing to crimes they didn’t do. Tactics like this cause that to happen constantly. When under immense stress people will confess to get the stress to go away whether they did it or not.

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mrwho2019 t1_j28597n wrote

It's called a polygraph, not a lie-detector test.

Scientifically they are highly inaccurate.

The test and the results can be affected by a number of factors.

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ScimitarPufferfish t1_j284lq6 wrote

They are indeed highly accurate (in measuring stress). Nothing more. "Lie detectors" are just machines measuring stress-related data coupled with a big dollop of subjective interpretation of said data.

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Treviathan88 t1_j285fcz wrote

Polygraphs as "lie detectors" are not accurate at all. They don't measure truthfulness in any way, only physiology. And while the two might be very loosely related, it's a logical fallacy. Correlation does not equal causation.

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greatdrams23 t1_j288q8e wrote

The clue is in the question. If they were accurate, they would be used in every single criminal case.

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Aussie_Mo_Bro t1_j288lxp wrote

They are equivocally, with no shred of a doubt

#not

accurate.

Not only that, they can easily be fooled. Like, stupidly easily.

They need to measure a "baseline" to get your "at rest" heartrate, breathing, body temperature, etc. Just hold your breath for a bit, this can fool the baseline.

Fun fact:

William Moulton Marston invented the polygraph test.

He and his wife created Wonder Woman.

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Fred2718 t1_j28l5hy wrote

So...forget the polygraph. I want to be interrogated with the Lasso of Truth!

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flippythemaster t1_j290t5d wrote

He also was really into bondage. The lasso of truth makes sense now

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Mammoth-Mud-9609 t1_j2874jd wrote

They aren't even slightly accurate let alone highly, the only use they have is an interrogation tool for suspects who don't know how useless they are.

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2minutespastmidnight t1_j292rcb wrote

Here is a copy/paste from an earlier submission of mine regarding the polygraph. I didn’t change any of the formatting, so you’ll see that my answer was originally meant for someone else. However, these answers are still relevant to your question.

I submitted a paper in a college about whether the polygraph should be used in investigations at all for a forensic criminalistics course. There's a rather long history with respect to the device. You probably know the courts have ruled that, in general, the results from a polygraph are not admissible in court. This dates back to the outcome of a 1923 D.C. Circuit of Appeals Court case known as Frye v. United States where it was debated whether the polygraph met the standard of general acceptance (accepted within the "relevant scientific community").

I have no formal experience with the polygraph. This was just an assignment for a class. The device itself measures physiological responses that are often "associated" with deception. These responses include your heart rate, your breathing patterns, any sweating, systolic blood pressure, and sometimes a voice-stress analyzer.

You asked if polygraph tests are reliable. In my opinion, they are "reliable" to the degree of the relationship between the examiner administering the questions and the person undergoing the test; it's more of a game of psychological dominance on the part of the examiner. This goes to your second question on whether it is easy to "fake" it. It's not so much about whether it's easy to fake, but rather your perception of the device as well as your reaction to the questions being asked. This moves into your third question. Polygraph tests are used to measure your responses between two categories of questions: control questions and relevant questions. There are neutral questions as well that serve to create a baseline response such as "Is your first name ____?"

Control questions are questions where pretty much none of us could answer with 100% honesty such as "Have you ever told a lie to your parents?" or "Did you ever cheat on a test in school?". The examiner knows this and will assume you're not telling the truth. This is done by design. These questions aren't the ones that matter.

Next, you'll be asked a relevant question in which the examiner wants to get VERY specific on a certain subject such as with the use of illegal drugs or whether you knowingly omitted anything on your background questionnaire. Your responses to these questions are measured against your responses to your control questions. This is what helps to determine your "truthfulness".

That's pretty much how they work.

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Flair_Helper t1_j295h54 wrote

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abbscachoo t1_j297dls wrote

I had to take a polygraph once. Told everyone I was going to because I thought it was interesting.

First question, “did you tell anyone you are taking a polygraph today?”

“No”

pass

It’s not reliable or accurate. But it is a decent tool for making people break under the pressure.

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Mumblerumble t1_j28otdt wrote

In short, they’re not accurate. They show whether your body displays signs of being anxious.

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[deleted] t1_j284kg9 wrote

[removed]

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NemesisSenpai OP t1_j284r0m wrote

If you have done nothing wrong, you wouldn't have anything to be nervous about.

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ScimitarPufferfish t1_j284wy7 wrote

You don't think the average person might be a tad nervous about appearing in court? Whoops, looks like your heartbeat is a bit elevated! Guilty you are, off to jail with you.

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Theyos t1_j284zjb wrote

Because, as we all know people have no reason at all to be anxious when held by the police, even when innocent.

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NameUnavail t1_j2851i3 wrote

Yes because the justice system has famously never done something like coerce a confession, or falsely sentence someone.

No need at all for an innocent person to be nervous in a police interview.

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sim_kay t1_j28512y wrote

Yeah, that's highly unlikely.. Who wouldn't be nervous when interrogated by the police, even if you did nothing wrong? And than on the other hand there are sociopaths and psychopaths who are absolutely calm even if they murdered anyone. What would you do with them? Don't convict them because of the test?

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DrMcDingus t1_j2852j5 wrote

Would you not be nervous about failing? Have you never done anything wrong? All people have, maybe not the same wrong the police is asking about.

Lie detectors are pseudoscience and have no place in a justice system.

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Musicman1972 t1_j287bsc wrote

You would if you're sitting in a police station with detectives saying they think you did it and you will go down for 20 years.

That scenario wouldn't make you nervous?

Do you know who it wouldn't make nervous? A sociopath with zero feelings.

I don't like the machine that thinks stress == guilt.

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FailureToReason t1_j2876s4 wrote

Except that it doesnt work like that. What if you're nervous not about the questions relating to a crime, but simply the fact that you're jammed in a small, bright room with cops who accusing you of a crime? Or what if you're nervous that they might get a bad reading and think you're lying when you're telling the truth? What if you clench your anus at the wrong moment? I guarantee you an innocent person is going to be plenty nervous and stressed going into a polygraph, and that's exactly what the polygraph is trying to measure.

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Hitchie_Rawtin t1_j28lvte wrote

It's extremely common for people to feel nervous when going through airport security despite doing absolutely nothing wrong, you think people wouldn't feel nervous while being interrogated for a serious crime by a cop whose questions are presuming your guilt?

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