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Comment by moomin | Hacker News Reader

It's a bit of a joke, really. I doubt there's anyone reading this on here who didn't already know polygraphs don't work. The only people who don't seem to know polygraphs don't work are the ones making national security decisions relating to polygraphs.

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The polygraph process is not a technical one, but a psychological one. The point is not to detect a lie by "registering it" on the tool, its to create a situation where a person self-elects information because they believe the machine _could_ detect a lie. Its a huge dog-and-pony show, and the poly operators play it as a big game.

So, polys _do_ sort of work, but not in the way they are presented to the public.

My guess is that this works just like how it does in corporate security: It is vastly easier to add a new security policy than it is to remove it. Even when everyone knows something is useless or perhaps even harmful, nobody wants to be in a position to be held culpable on the off chance that retiring the policy is implicated in a future breach.

Polygraphs are a $2 billion industry, and Upton Sinclair said it best: "It is difficult to get a man to understand something, when his salary depends on his not understanding it."

Sure, but what about the people buying polygraphs?

Their jobs depend on the polygraph existing as a credible institution

The trope that they are meaningful continues on shows like "Dateline" where local cops drop "persons of interest" after "passing" one. And insinuate that someone that refuses one is guilty, etc. It's really odd to me that the general public has no idea that polygraphs are complete bullshit.

let's get real, polygraphs are a ruse in order to humiliate people and see how they react in torture situations. Using them is a power play. It lets the victim know who the boss is.

Polygraphs are there to create a high-stakes stress/interrogation situation to see if someone cracks or reacts. It's more of an art form than a science -- and that's why it's not admissible as evidence in a criminal investigation (and shouldn't be)

The rationale for continued use in clearance screenings is that it's not scientific, but it's better than nothing.

I don't think it is better than nothing at all. Passing a polygraph test is now potentially a false signal, giving a false sense of security to the parties concerned. Without a signal the situation would be better.

Partly its that. Partly its about tricking juries, "He failed/refused the polygraph" is a very nice way to discredit someone. At least 5 of the 12 people there will find that concerning and not know its BS.

Any lawyers in the house? I was under the impression that (in the US) refusing to take a polygraph was not considered an admission of guilt though could be grounds for dismissal from federal employment.

What's legal has nothing to do with swaying a jury.

If the opposing side brought up refusing to take a polygraph you would object and ask the judge to explain to the jury why that had to be disregarded, right?

I doubt that any judge would allow that to even be brought up in a trial. If it were, it would probably be an appealable issue that would get the case thrown out.

I thought polygraphs are prohibited in courts in most jurisdictions?

It's used in criminal courts 19 states and at the federal level by the disgression of the judge. Plus it's used in a bunch of "non-court but legal process" like for people on probation.

https://en.wikipedia.org/wiki/Polygraph#United_States

Interestingly (last paragraph of the link above) the US has indicted people for offering to teach other how to beat the test!?

This seems like a pretty adversarial way to look at it, using words like "power play" and "victim." From my understanding the CIA still regularly uses polygraphs. I have to wonder why that is, and it may have nothing to do with the polygraph itself. Maybe it's more just making sure someone has nothing to hide? I'm also not sure what "beating" the polygraph means in the context of them not working in the first place. How do you beat something that doesn't do what it purports to do?

I've talked to someone who administers polygraphs, and they said the machine is mostly theatre, but that there is normally someone watching you through a hidden camera or double sided mirror to see how you act when you think someone isn't looking. For example, when I had to take a polygraph for work, the polygrapher left the room a few times because they "needed to get a second opinion about abnormal results". That's when the hidden person would supposedly be watching to see if I acted differently when I thought I was alone.

That process sounds even more scientifically dubious than the demonstrably dubious machine.

Indeed, but no more so than any interview process. Perhaps they should use a whiteboard instead?

right, when left alone the subject started flipping a coin (one side of which was disfigured) manically, and seeming to have an argument with themselves, sometimes shouting "you're guilty, you know it" and other times growling "those coppers will never crack me".

Beating the polygraph means passing it when you're lying about the relevant issues. Although polygraphy has no scientific basis, the methodology employed makes effective countermeasures possible.

I'm not sure how stupid a spy would have to be for "are you a spy? Be honest!" questions to work. But if I were running an organisation I suppose I'd have people ask anyway because it'll catch some idiot sooner or later.

Polygraphs as a power play - well, I'm sure it happens but that probably isn't the reason it is in the room. Maybe the polygraph is a ruse to make people think FBI questioners are stupider than they really are? I can see value in having a distraction from the actual questions.

> I'm not sure how stupid a spy would have to be for "are you a spy? Be honest!" questions to work. But if I were running an organisation I suppose I'd have people ask anyway because it'll catch some idiot sooner or later.

Those are questions on the SF-86. Ditto for a lot of customs & immigration paperwork. "Idiot detector" questions.

But if you don't have them on there then they can claim "but you never asked".

Yep, it's also another line item when charges are brought. Kind of similar to how states like Tennessee that don't have legalized marijuana still have a tax stamp process. I doubt anyone ever applied for one, but if you get caught with some pot, boom pot and failure to present tax stamp. Two for one.

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