GSR History: An often misunderstood and difficult technique, GSR has gone through many phases of interest and rejection since the early 1900's. It has been used in important research on anxiety and stress levels (Fenz & Epstein, ' 67); and it has been a part of lie detection (Raskin, ' 73). Controversy has centered around the technique, underlying mechanisms, and the meaning of the responses obtained from the skin.

There has been a long history of electrodermal activity research, most of it dealing with spontaneos fluctuations. Most investigators accept the phenomenon without understanding exactly what it means (Hume, ' 76). Although GSR is the oldest and yet most confusing term, it is also the one in common use. Many attempts have been made to improve and update the terminology; two such systems are proposed by the Society for Psychophysiological Reaserch (Brown, ' 67), and Venables & Martin ( '67). Electrodermal response ( EDR ) is the umbrella under which the terms fall.

Basically there are two techniques in the history of Electrodermal measurement. In one a current is passed thru the skin and the resistance to passage is measured; in the other no current is used externally and the skin itself is the source of electrical activity.

GSR Physiology: Easily measured and relatively reliable, GSR has been used as an index for those who need some measurable parameter of a person's internal "state". As in EEG, there is not a clear understanding of what the measures reflect. Physiology, the GSR reflescts sweat gland activity and changes in the sympathetic nervous system and measurement variables. Measured from the palm or fingertips, there are changes in the relative conductance of a small electrical current between the electrodes. The activity of the sweat glands in response to sympathetic nervous stimulation ( Increased sympathetic activation ) results in an increase in the level of conductance. There is a relationship between sympathetic activity and emotional arousal, although one cannot identify the specific emotion being elicited. Fear, anger, startle response, orienting response and sexual feelings are all among the emotions which may produce similar GSR responces.

GSR History, & Physiology taken from BIOFEEDBACK Methods and Procedures in clinical practice ( 1977) written by George D Fuller, Ph.D.