How exactly are polygraphs supposed to work?
A. Polygraph testing is based on the flawed assumption that fluctuations in breathing, pulse rate, blood pressure, and perspiration are indicative of deception. In a nutshell, a polygrapher compares a subject’s physiological responses to a question where the individual is supposedly tricked into lying (a “control question”) with his/her response to a question concerning the matter being investigated. If reactions to the “control” question are greater, the subject is deemed truthful. If reactions to the question on which the polygrapher is attempting to determine truth or deception are greater, the subject “fails.” If reactions to both are approximately the same in size, the “test” is termed inconclusive.
