Here is a Penn & Teller Episode about polygraph tests. They talk a little about the history of polygraph tests, talk a lot about skepticisms of the test, as well as ways to fool a polygraph.
They use a lot of profanity, especially the f bomb, so if you are offended by this, please don't watch!
Part 1: http://www.youtube.com/watch?v=u9NSXy176oA&NR=1
Part 2: http://www.youtube.com/watch?v=bScv6kfxRyE&feature=related
They use a lot of profanity, especially the f bomb, so if you are offended by this, please don't watch!
Part 1: http://www.youtube.com/watch?v=u9NSXy176oA&NR=1
Part 2: http://www.youtube.com/watch?v=bScv6kfxRyE&feature=related
Oh I just have to comment about this one. Don't get me wrong, I love watching this show, but it does have an agenda. I will agree with the show on many points, and I'd agree that the polygraph test is BS. It's been awhile since I’ve seen this episode, but I did watch the first part to give myself a refresher.
I've had an opportunity to be polygraph tested by a real interrogator (he was a friend and we were bored). I was hooked up and he started to ask me general questions he knew the answer to. I complied up to a certain point, where I started giving false answers intentionally to ridiculous questions, like if I killed Kennedy. According to the polygraph test, I was telling the truth (or at LEAST I "believed" I did). The way I did this was I remained calm and collected no matter what he would ask me. For a second "fun" test, I decided to run a few laps and get my heart rate up. I strapped back in and he asked me his typical basic questions... According to the machine, I lied about everything, including my real name.
The point of the story, other than being a little fun, was that polygraph merely tests stress responses. As the show pointed out, if you have a strong emotion when answering a question truthful, the machine could mark it as a lie. My friend also told me that pain responses could alter the readings in typically a negative fashion. In this case, you would give your lie, the machine would show it as a lie, and it would make the proctor confused why you would lie by admitting to a crime.