Riley,

With regard to the "clamp" placed on a finger, I assume that you are referring to the two electrodes associated with the electrodermal (also called "galvanic skin response") channel of the polygraph instrument. While the electrodermal channel cannot be directly manipulated in the same way as the pneumo (breathing) channels can be, countermeasures such as breathing manipulation, tongue biting, the anal sphincter contraction, and mental countermeasures are likely to produce a response on the electrodermal channel.

Note that reactions only to the "control" questions should be augmented (not to the irrelevant questions). It would be prudent to review Chapter 3 of The Lie Behind the Lie Detector, which explains how to differentiate between relevant, irrelevant, and "control" questions.