Silenced research: lie detectors don't work

Do they work?

It depends on how you ask the question; how do you define 'work'.

If we define 'work' strictly as being able to determine a single given truth from a single given lie, my understanding is that they are better than chance, but not much more so.

This understanding stems from studies and mega-studies discussed on this forum in the past; not by any means conclusive.

I personally would not take one unless someone double-dogged-dared me (or IOW, if the result would not follow me).
 
Rasmus said:
What happens if you want to leave your job and fail the test? Do they force you to keep working there for another three months?

If you fail one of the tests whilst working there, will it all be good if you simply claim you were going to quit anyway? :duck:
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that's an easy question. In some jobs, 'failing' the poly, regardless of when, can have ... career-changing ... implications (re: FBI/CIA/Military security clearance).
 
The job applications for those positions included the word "death" (yours) if you screwed up about classified stuff.
These weren't your MacJobs!
 
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jimtron said:
I thought it was always known that they don't work. It was my impression that they were used more for intimidation or coaxing confessions than anything else. In any case I don't think it was ever claimed that they detect lies, despite the name.
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The only thing I found at all surprising was the claim that "lie detectors" work no better than chance. I thought it was pretty well known that polygraphs were not very reliable. Evidence from polygraphs is generally not admissible in court (at least in USA).
 
This is just from memory, but I have looked into lie detectors.

Polygraphs, when using the Control Question Test method, are ~70% accurate (or their operators are) at detecting lies in experiments.

Voice stress analysers usually turn out to ~50% accurate in experiments: the same as guessing or flipping a coin.

In experiments the actual (or ground) truth is already known, of course.

So the polygraph is slightly better than guessing, gut instinct, and even better than people trained to spot lying (micro-expressions etc. who score ~63%) but still nowhere near accurate enough to be used reliably.
 
Professor Yaffle said:
To reiterate, the OP seems to be referring to voice analysis, not your usual polygraph lie detector.
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I replied before reading whole thread, so I missed that they were talking about voice analyzers. However, I think it's been known for a long time that they are completely useless.

There was an excellent episode on the old "Barney Miller" show (which was a comedy about a police precinct station), many years ago. Internal Affairs was investigating something or other, and interviewing officers using a voice analyzer. One of the officers got upset by some questions, and failed the test. Another officer, when asked where he was born said "I was born long ago in a galaxy far away" and gave similarly fanciful answers to other questions, all of which the machine indicated were truthful.
 
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