Lie detectors. Any good?

Since the site from which I got this is a little biased, I’m not saying to take everything in it to heart, but it is an interesting read:
One excerpt from it that I found hilarious, even if probably an urban legend is this:

:smack: Hit “Submit Reply” instead of “Preview Post.”

Here’s the link I meant to include:

http://www.stopolygraph.com/polygraph/nf_susanmccarthy1.htm

This is the exact routine they followed on Homicide:Life On The Street, when Munch and the older cop, played by Ned Beatty, question a gang member. Munch adds to the fun by saying gravely to the suspect that he doesn’t want to stay in the room while the test takes place because radiation from the machine can lead to ‘penile stultitude’.

Whether the script writers picked up a well-known anecdote, or the program itself originated the joke is anybody’s guess.

I took a lie detector test once, and by mistake they put me where I could see the needles in a mirror.
The needles wiggle before you answer. In other words, if the question makes you wonder what to say, i.e. if there is any doubt, if the question males you tense up.
In my case they asked if I had ever stolen anything. Because I wasn’t sure if they meant about the crime in question or about swiping pennies from my brother’s piggybank as a kid, I asked them to clarify. They said the test was spoiled by my asking questions and they re-ran it. Lucky for me, or my doubt would have looked like guilt.

I had heard this story/technique several times before Homicide was ever aired.

When I first heard of the “photcopier trick” on one of those TV investigative report shows [60 minutes?] the suspect was an innocent mentally retarded black man who was tricked into confessing to something he hadn’t done by a law enforcement officer somewhere in the rural south.

And this is why a lie detector occasionally might work. I have taken a lie detector test, and let me tell you this is a pretty dumb idea. Doing something like this would be easily caught by the operator giving the test, and you would then fail as you clearly had something to hide!

You are hooked up to the machine even when you aren’t answering questions, and stressing out on every question is immediately suspicious. Once the operator takes a closer look at you, he/she is going to be able to tell that you are jabbing yourself. I’m not sure how you are supposed to bite your tongue while talking without the operator knowing. Your hands must be flat against the chair arms while the questions are being asked, so you can’t use your fingernails. Not to mention the fact that you must sit completely still, and any motion will be picked up by the pressure plate in the seat. And how do you walk without limping with a tack in your shoe?

The best way to beat it is to do what convicted spy Aldrich Ames did. When he heard he had to take the test, he asked his KGB handlers how he could beat it. And they told him: just relax, the polygraph just isn’t very good. That’s it, you don’t need any tricks. That’s just what Ames did, and he passed every one they gave him.