Comments on: The Truth About Lie Detectors

By: kelly

kelly — Thu, 18 Jun 2009 04:05:00 +0000

I had to take a voice stress test once (a version of the lie detector) I only lied on one question, but it said i lied on almost all of them. I held my ground, though, since I figured they were just trying to get me to confess. I didn’t actually do anything though, so I was pissed when it said i lied when i didn’t. The guy giving it said it was 99.9% accurate, but obviously it was not.

By: Dave

Dave — Mon, 15 Dec 2008 05:49:00 +0000

I remember a story about some cops during an interrogation who put a colander on a guy’s head with wires leading to a copy machine. Every time they’d ask him a question, someone would hit the copy button and a sheet of paper saying “He’s Lying” would come out. He confessed.

Would that be lie detection via placebo? Or just a stupid crook?

By: Gabacho Mike

Gabacho Mike — Sun, 14 Dec 2008 11:40:00 +0000

i’ve also heard that in some military circles, training has been given to deter/obfuscate a lie-detector (if caught, i would imagine).

If this is true…and i’m sure it’s not that hard to ‘redefine’ the question being asked, before answering…then the rest is also hooey.

By: nathenism

nathenism — Sun, 14 Dec 2008 04:18:00 +0000

i dont think the test proves anything but that the person’s heartbeat quickened when he answered the question and so its completely useless…but unfortunately cops are willing to believe anything that makes a person look guilty

By: Holly B

Holly B — Sat, 13 Dec 2008 13:59:00 +0000

I used to work in a sheriff’s office that required all potential employees to pass a lie detector test as if it were a valid screening device.

The key value of a lie detector machine is in convincing subjects they’ve been found out and had better confess. That’s one reason somebody conducting the test invariably ask an identical question two or three times. There’s a natural tendency to assume that getting asked the same question means your first reply registered as false. From that point, a trained interrogator will have an easier time to provoke confessions from dumb people who fear the machine is legit.

Smoke and mirrors — that’s all that lie detector machines amount to.

By: Orange

Orange — Fri, 12 Dec 2008 18:56:00 +0000

A family member of mine worked at the FBI for awhile, and part of the screening involved was a lie detector test–this was in 1999.

From what she said, they asked you questions that they made you lie about so they could measure what exactly your body does when a lie is told. It seems to me that that would help with the accuracy of the test, but as many have pointed out, they are by no means foolproof. They can be tricked and pathological liars can pass them.

By: Pete

Pete — Fri, 12 Dec 2008 18:45:00 +0000

The way to beat lie detectors is not to try to remain calm during the lie, as that can be difficult, but to be agitated throughout the testing so that the lies and truths are physiologically indistinguishable. For example, right before answering every question you do something that causes yourself some slight pain — bite your tongue, pinch your leg, something like that. The pain will cause your blood pressure and heart rate to rise. The machine will then record the same physical responses with regard to every question, and it looks like there are no lies.

By the way, polygraphs are so out of favor that Congress passed a law basically prohibiting employers from using polygraphs in the employment context — the Employee Polygraph Protection Act (EPPA).

By: Mare

Mare — Fri, 12 Dec 2008 17:53:00 +0000

Hey BassMan:

What’s the biggest, or most expensive, or most ongoing thing you’ve ever stolen from an employer?

Also – Mental Floss – this’d be a cool
@ of the Day – are there famous cases of workplace hoarding and stealing?

BTW I used to work in a movie theatre and we had a really gross way of balancing the count…. so that we could have free candy.

By: BassMan

BassMan — Fri, 12 Dec 2008 17:32:00 +0000

I, too, took a lie detector test in the ’80s for employment. (Mine wasn’t a ‘certain company’, it was RiteAid.)Apparently, I passed.

They ask a few obvious questions: “Is your name…” and the like. I guess this establishes your patterns so they can differentiate your truth from lies.

The trouble with these tests, or any simlilar test or survey is that the questions are necessarily phrased as yes-or-no.

Now, when asked if you’ve ever stolen from an employer, for the overwhelming majority of us the answer is yes. You did not buy that pen and you know it is not yours and that your employer doesn’t want you to take it home. But, gee, does that really count? Now you’re really nervous. How do you answer?

That may be a lame example but it’s all I could think of. The point is the questions can be faulty causing you to answer them in ways that are essentially honest, but may indicate dishonesty. A machine cannot make that judgment.
(If anyone knows what I mean and can explain it better, please do.)

Also, I would assume sociopaths can easily pass them.

By: Bryan

Bryan — Fri, 12 Dec 2008 17:25:00 +0000

Obviously there’s tons of people who would naturally be nervous to take the test even if they had nothing to hide. I think the test facilitor begins the test with normal questions like, “Is your name _______?” They measure your blood pressure and pulse during these obvious truths and falsies and compare them to what happens when they ask the “real” questions. I think the only way to fool the test would be to have the ability to stay calm during it’s entirety.

In my uneducated and spontaneous opinion that has no credibility, these tests are usually right. Unfortunately, “usually” doesn’t hold up in court.