The Truth About Lie Detectors

How do polygraphs work, and do they actually detect lies?

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[sturdybutter]

Even though the courts where I live have ruled polygraphs as insubstantial evidence, the police and sheriffs office still use them as an intimidation factor.

[gerwaldlindhelm]

I was falsely accused once, so I asked for a polygraph. My lawyer adviced against it. She said that if I failed, they would use it against me. If I passed, they would not admit it as evidence because it has a 20% error rate on average. So taking a polygraph is a lose lose situation. I got my name cleared at the end, but it took a long time to fight the burocracy

[bobowon]

i'll never forget when they hooked a lie detector up to a plant and when it got a reading they came to the conclusion that plants have emotions rather than the conclusion that maybe its not a reliable test of someone telling a lie

[morpho]

My forensics professor, a Veteran SFPD detective of 40 years and an extra in Dirty Harry described polygraph tests as "pseudoscience bullshit we throw at stupid people to trick them into a confession".

Luke being a non-serial-killer? I have my doubts. I mean what kind of non-serial-killer owns birds? That is strictly a serial-killer thing.

[dogboy]

My brother failed 5 polygraph sessions scheduled across multiple months that were for a job interview. They are incredibly inconsistent. He apparently murdered and then unmurdered a guy based off their results. They had to keep rescheduling him because the results were so bad.

[beni]

Many people I know used to do the polygraph for their government clearances and said that, not only is it too stressful and annoying (especially because you have to redo it every 5 years), but also they often fail them 1 or 2 times before passing anyway, drawing out the entire process. Its also worth mentioning that the polygrapher is major element in how well you do on the test, some will blatantly accuse you of being a terrorist in an aggressive tone, while others will speak calmly and ask you less leading questions. Its becoming a lot more common for people to just stop renewing their higher level clearance if they don't NEED it.

[Rurik_Luci]

A polygraph is inadmissible in court

Also it's pretty much the worlds most expensive blood pressure machine

[TheDarkPreacher]

I could never pass a polygraph, even if I told nothing but the truth because I have asthma, PTSD, low blood pressure, and a sinus arrythmia in my heart that causes my heartrate to vary with inhale and exhale. It's not steady, and therefore would make everything read as "lie".

[captante]

There's no such thing as a "lie detector" .... only a "reaction" detector. And since the polygraph operator has exactly ZERO ability to know why a person reacts to a certain question a certain way beyond assumption, they're near-worthless for sniffing out lies reliably. And whats worse the cops KNOW THIS very well.

[ArniesTech]

There is no better lie detector than an angry mom who just called you by your first AND last name. Better confess to prevent worse.

[arithex]

"It's not a lie .. if you *believe* it."
-- George Costanza

[iammaxhailme]

law enforcement doesn't use polygraphs in order to avoid hiring criminals. they use it to avoid hiring bad liars who might embarass them in front of congress when they fail to lie convincingly

[sutton]

Hearing how all this works would already make me frozen with anxiety, before the test would even start.

[kaleckton]

Linus forgot the most important thing in this. Anything you say before, during and after the test can be used against you in court. They don't need a warrant and it's considered to be voluntary information so you don't even need to be under arrest. So you can state a fact after passing the test and the administrator for test can testify against you. For some it's even a strategy to talk you up, especially if they have you with no lawyer. Or at least like this in the USA with some differences state to state.

[Phytom]

1:03 Yeah, my heartrate definetly wouldn't go up if I'd be strapped like this in a court and questioned whether I'd killed somebody.

[krinniv]

See, Luke's a normal killer, not a serial killer

[littleboyred]

As someone who's neurodivergent and been through a bunch of, to put it nicely, _unfair treatment_ toward me and my circumstances- Explaining _literally anything_ is both challenging and stressful to me. Especially anything with even the slightest implication of being accused of something, even inconsequential things. Telling the truth is also _more stressful_ to me than lying, due to fear of critical, truthful information being considered false if i don't explain myself _perfectly._

If anything a lie detector might be the opposite of helpful for someone like me.

[TheCainabis]

My friend had 65k stolen from my house (which I was keeping safe) I was a drug courier for him, he booked me and another courier in for a polygraph test, nervous as hell I carried on with the test with nothing to hide! I even failed on questions that were true, I got a 99% deception rate and he believed the polygraph over me and put a hit on my head! (As of now it’s still continuing) these things are absolutely bull sh*t

[bargh]

Polygraph tests are the buzzfeed quizzes of the judicial system.