I do not have information on whether the USSS is using sensor pads in conjunction with its polygraph instruments. While the ability of such devices to reliably detect such polygraph countermeasures as the anal sphincter contraction remains unproven, as a precaution, you might wish to use mental countermeasures instead (for example, thinking frightening or exiting thoughts or doing mental arithmetic when the "control" questions are asked). The available peer-reviewed research suggests that mental countermeasures are just as effective as physical countermeasures. Another alternative countermeasure is to bite down slowly on the side of one's tongue enough to produce moderate pain. Both of these techniques are discussed in Chapter 4 of The Lie Behind the Lie Detector.

Just go in, with the expectation that you will not "pass".
Do not admit to anything significant, and remember that
a failed poly may impact other security clearances.  Since
you have read the DoDPI, just enjoy watching their role
playing; if they start any verbal abuse, just ignore
and do not engage them.  Do not give them an opening
into anything significant; do not be suckered, when they
act as your friend, against the institution.  Sit down and
watch a few episodes of, "Law and Order", to get a feel
of interrogation techniques (lies and deceptions).

I have studied both extensively, "The Lie Behind..." and the DODPI Pre-Employment Test manual.  I actually was having one of those nervous days yesterday, but re-read parts of each for about an hour, and am now having one of those confident days.   

How much do you think the "first impression" plays in the role of a federal polygraph?  Do you believe that the impression you give the polygrapher will help in determining how they interpret the charts?

Another question I have which is not really mentioned in much detail is the usual physical layout of the exam.  Where does the polygrapher sit in the room in relation to the examinee.  Would they sit behind me, beside me?   

And George, I know I am a newly joined member, but I have been visiting your sight for over 6 months.  Very valuable information, I would be "Scared As Hell" even worse if I was going into this exam blind.  Thank you for the valuable info.