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Electrodermal
One physiological phenomenon that has been studied by scientists for over 100 years is the electrodermal response (EDR). Older literature refers to it as the Galvanic Skin Response (GSR). Strong EDRs are often seen on the polygraph when a person lies, and they are considered the best indicators of deception. The EDR is recorded with two sensors that are placed on the finger or palm. A minute amount of electricity is passed between the sensors. When the skin becomes more moist, the electricity passes between the sensors more easily, and the change in electrical conductivity is registered by the polygraph. If certain questions repeatedly cause EDRs to occur during polygraph testing, it is an indication that the person has not told the entire truth to those questions. The diagram below shows typical EDRs from a polygraph examination.
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