Comment by parsimo2010 | Hacker News Reader

Comment by parsimo2010 | Hacker News Reader

Most of us can’t reliably tell when a romantic interest is actively signaling their mutual interest. If we can’t get cooperative activities right, most of us don’t have a chance to spot a liar through nonverbal cues. The fact is that random effects are huge when dealing with people. Is that person you’re interrogating not showing emotion because they’re a psychopath, or because they were taught not to display emotion? Is someone not looking a cop in the eye because they are lying, or because staring someone in the eye is perceived as defiance in many cultures and they don’t want to anger the cop? We’ll probably never be perfectly accurate at spotting lies. A bunch of biometric measurements might help, but current polygraph techniques can allegedly be beaten with training. If trained polygraph techs with special equipment can be beat I don’t know what rules of thumb we’re ever going to give to the general public that will work.

If you know someone really well, you might have a decent chance of knowing when they are acting unusual. Such is the case with parents and teenagers, but suspicion often gets the best of the parents and they misinterpret the cues that they spotted.

A good method would seem to be to catch someone on a logical contradiction, but that has issues when someone is under emotional distress. And emotional distress tends to appear often when someone is innocent but is afraid the evidence points towards them. The family cat may have knocked over Mom’s favorite vase, but the child is less interested in the truth and more interested in avoiding a spanking- so they embellish whatever story they had (in a misguided attempt to make it more believable), which introduces contradictions that the mom notices. The kid technically lied with the embellishments but was innocent of breaking a vase, and gets spanked when they didn’t deserve it. Then imagine the kid’s emotional distress being even higher the next time something happens.

I’m sure that there are a lot of learned people out there that study lying, but I agree with the article’s main theme that most of us can’t reliably tell when our why someone is lying, and we’re overconfident in our abilities.

There’s an interesting take[0] on defensive mechanisms societies have apparently evolved in order to detect a psychopath in their midst in daily life without having to know that person for a long time.

[0] https://www.ribbonfarm.com/2016/05/05/dares-costly-signals-a... on dares and costly signals, also discussing The Psychopath Code by late Pieter Hintjens.

interesting, you should submit this as a top level post

What? The zeromq guy died?

Yes. He was diagnosed with lung cancer and chose euthanasia. http://hintjens.com/blog:115 and https://twitter.com/hintjens/status/783254242052206592

> current polygraph techniques can allegedly be beaten with training

No training is needed because polygraphs don't work. Polygraph testing is about as worthwhile as astrology:

https://www.apa.org/research/action/polygraph

https://www.salon.com/2000/03/02/polygraph/

And inadmissible in court in many places:

http://www.austlii.edu.au/au/journals/MurUEJL/2000/6.html

> if trained polygraph techs with special equipment

There are no trained polygraph techs. They are, at best, con artists.

That your post has been downvoted is disheartening. Your reply was factually correct, cited, and reasonably polite.

Perhaps instead of saying "at best" they are con artists, it would have been more polite to say at worst, they are con artists. Probably many earnestly believe in what they are doing, and are just wrong.

One thing to add:

> And inadmissible in court in many places:

I'm not aware of any place that accepts polygraphs in a court.

Then I'll quote the article:

"In the United States of America, (where polygraph testing is a growth industry) the admissibility of lie detector test results is determined by courts and legislators on a State by State basis.

In the Federal legal system, test results are inadmissible as substantive evidence. Whilst some States have allowed test results in criminal trials, States such as such as California have prohibited the admission of such evidence unless all parties consent to its admission."

> It is difficult to get a man to understand something when his salary depends upon his not understanding it.

To be precise: a lot of people (even on hn, especially on hn) are personally and practically invested in authoritarian practices being legitimate.

I’m kinda surprised. I felt this group was much more rebellious a few years ago. A lot of people might say it’s growing up, but I still don’t like it.

I look back on the people I admired, and they questioned authority.

To vehemently support the policy of the hour as moral and correct, and then to be later shown to be wrong. At best a fool and at worst a criminal. Is more than many can tolerate. They would rather maintain the lie in the face of all evidence.

It really doesn't matter how earnest they are when polygraphs have been known to be garbage pseudoscience for decades, and especially when people's lives can be derailed by the fraudulent "results" obtained from a polygraph or even just the fiction that it can get results:

https://www.bloomberg.com/graphics/2015-doug-williams-war-on...

Calling them con artists is about as polite as I can be.

I’m not going to vigorously defend polygraphs, but I’ll play Devil’s advocate for a bit. From your the Salon piece you linked to, “In studies, polygraph diagnoses are often wrong, with rates hovering around 80 percent correct”

Which to some people sounds terrible. I certainly wouldn’t want to hang a murder conviction on something with a 20 percent error rate. But on the other hand, 80 percent is better than all but one of the cited results from the Atlantic article, and beats the results from all experiments using untrained people. These con artists are, at best, performing on par with specific lie detection training.

Maybe the equipment is just for show, but who’s to say that further biometric measurements, such as functional MRI, wouldn’t significantly increase the accuracy of biometric lie detection (still technically within the realm of nonverbal cues from the Atlantic article)? I don’t think it could be 100% accurate, but I can reasonably see future polygraphs being legitimate tools for lie detection.

I wouldn’t want my murder conviction to hang on the results of a current polygraph, but I would be satisfied using one to catch an office supply thief. Well, except it would probably be cheaper to just let someone keep stealing supplies than to pay $8k per employee to administer the tests.

> Maybe the equipment is just for show

Yes, it's a con.

> but who’s to say that further biometric measurements, such as functional MRI, wouldn’t significantly increase the accuracy of biometric lie detection

That isn't what they're doing. The "who" that will say it is actual, statistically significant evidence that it works.

The US government still requires polygraphs as a condition of having administrative access to classified systems. They're one data point of many, since you already have a clearance and were thoroughly investigated by other means, but this is an obvious area where it is acceptable to use shitty evidence. The cost of a false negative is extremely high, but the cost of a false positive is close to nothing. Any person who can't pass just has to get a different job.

Courts are the exact opposite situation and I hope the practice of using polygraphs in criminal investigations disappears at some point.

People tend to miss that the error rate in a diagnostic procedure is not enough to evaluate the usefulness of a procedure because you need the relative cost of different types of error as well. It's the same reason FAANGs can get away with shitty interview methods. Cost of false negatives is much higher than cost of false positives.

There is one weird bit of logic in favor of them in niche cases: they might be good at detecting people who have been trained to "pass" a polygraph test.

This is another good point: you can be interrogating (or interviewing) a suspect under investigation, use a withholding technique and successfully catch them in a lie, only to have them lying for a completely unrelated reason to the original inquiry. From what I've gathered, the best lies under interrogation are the ones with the most components of the truth and minimal superfluous information. The police will do everything to get you to talk and keep talking, which is why legal representation is so key.

It gets even hazier, frankly, when you realize that not every statement you make can be firmly categorized as a truth or lie. Due to cognitive dissonance our lies to others can soon become lies to ourselves, and where do you draw the line between wholly believing in a lie to yourself and being flat-out mistaken?

The people who study lying the most are the ones who counter it for a living: police, interrogators, investigators, and business people.

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