I had to take a poly because I am on probation and the only question on the poly that I "reacted" to was the one asking me if I had taken any illegal drugs. I was told I had an electro-dermal response, but my breathing and blood pressure were ok. I actually looked at the chart. How do electral dermal responses work? I really was telling the truth on all the questions so I think it's funny that I scored an "inconclusive" on that one, let alone any, but it's funnier because I've NEVER done any illegal drugs. So now I may have to write a paper on WHY I may have responsed to that question. I honestly don't recall thinking anything except listening to the questions and answering like we had gone over so many times before. Maybe if I better understood electrodermal responses, I may be able to track down why I had one?
the fact that you and probably 99% of the population have no idea what electrodermal response is, would most likely be why he is telling you that you are displaying a response in that area.
Remember, the poly is used mainly as an interrogational tool to get people to willingly confess to something. Much like the old cop line "well your friend is in the other room and telling us EVERYTHING" Your friend is probably just as quiet as you, but they are attempting to deceive you into making a confession. If you indeed were truthful, then the polygrapher is most likely just fishing for something, and usually they will come up with something. People have it in there nature to want to come clean and often will with a bit of encouragement.