I just wanted to post and say thank you thank you thank you for this site.  It is amazing to me that the majority of people (including myself before reading into it), buy into this scam, and that Polygraph testing is even still legal!  I had never even thought about Lie detector tests before recently, when I was accused by a co-worker's wife of being involved with him.  And I was NOT!! At first, I agreed instantly to a polygraph test with confidence, knowing that I have nothing to hide.  But I did some research anyway and came across this site, read 'The Lie Behind the Lie Detector', and realized that my genuine 'truth-telling' was not going to necessarily let me pass.. and there was no way that I was going to have the 'absolute' verdict of this accusation determined by one of these self-righteous phony polygraph examiners.
Well, I took my test today, and passed with flying colors.  However, even though I told the complete truth regarding the relevant questions, if I had not understood the use of the Control questions, I would have failed miserably.
Why?  because the control questions he chose to ask were based on an assumption he made about me which was not true, and the sad, illogical truth is that THE CONTROL QUESTIONS ARE THE ONLY ONES THAT ACTUALLY MATTER HOW YOU ANSWER. Had I answered the control questions truthfully without squeezing my sphinctor muscles, I would have failed the test, plain and simple.   
Another thing I want to emphasize to anyone facing a test, I would highly recommend reading the Interrogation document found on this site here: antipolygraph.org/documents/dodpi-interrogation.pdf
as I found that my behavior, body language, and attitude greatly helped me.  I also played dumb as a doornail, and fed the guy's ego like you wouldnt believe, which essentially won him over. I honestly think this is half the battle.. as these people are NOT on your side to begin with, but if you can get them to like you, they may actually go easier on you.  He fed me so much BS, and I looked at him in wonder, like I was impressed. No questions. This is what he wanted Thanks again for providing this valuable information and website. It is sad that this machine is still in use today and can ruin so many people's lives