Galvanic Skin Response (GSR)
Galvanic Skin Response can be described as a measured fluctuation in the electrical resistance of the skin.
Using a pair of electrodes usually connected to adjacent fingers, a small electrical current is passed through a subject's skin via one electrode and subsequently measured by another. By measuring changes in skin conductivity relative to applied stimuli, it has been proposed that not only can a subject's emotional or attentional reaction be measured but that the GSR can be considered relatively autonomic and not easily controlled by the subject.
(Greenfield and Steinback 1972)