As I learn more and more about the poly, I understand that it works only if you believe in it. Yet, I'm actually afraid that I'll fail because of all the horror stories I've read and fear that my body will betray me in giving a false response. It's like that nervous feeling where you see a cop while driving even though you've done nothing wrong (C'mon, I can't be the only innocent driver out there who feels this way). Yet, the underlying theory behind polygraphy is to interpret that as a deception, thereby yielding a false positive (and getting screwed). 

Example: I've never done illegal drugs. Yet, it sounds like 50% of FBI applicants get screwed on the drug question. So I'm concerned that my fear of triggering a false reaction is going to screw me, rather than the actual truth. Do you follow? It's the feeling of not having enough confidence that I can overcome the risk of a false positive and that my body will betray me and give a false reading/reaction. I would be wondering how I did on the drug question immediately after responding with a no (not because I'd be nervous that they'd find drug usage - because there wasn't- but that the wondering is due to my knowledge of the possibility of a false positive result... the anxiety?). This site has been a tremendous resource. At the same time, it has caused me to fear the false positive more than the actual relevant question itself. Maybe I'm psyching myself up too much by reading the horror stories, yet I appreciate the immense knowledge based on scientific facts and logical reasoning. Does anyone feel the same? If anything, I'd prefer a senior examiner just the off-chance that he or she has the integrity to continue digging as opposed to just relying on the machine's reading and a biased interpretation. Now isn't this ironic? This machine is too blunt of an instrument and the innocent ones with a guilty conscience becomes acceptable in the collateral damage it causes.