Galvanic skin response (GSR), also known as electrodermal response (EDR), psychogalvanic reflex (PGR), or skin conductance response (SCR), is a method of measuring the electrical resistance of the skin. There has been a long history of electrodermal activity research, most of it dealing with spontaneous fluctuations. Most investigators accept the phenomenon without understanding exactly what it means. There is a relationship between sympathetic activity and emotional arousal, although one cannot identify the specific emotion being elicited. The GSR is highly sensitive to emotions in some people. Fear, anger, startle response, orienting response and sexual feelings are all among the emotions which may produce similar GSR responses.
GSR measurement is also becoming commonplace in hypnotherapy and psychotherapy practice where it can be used as a method of detecting depth of hypnotic trance prior to suggestion therapy commencing. When traumatic material is experienced by the client (for example, during hypnoanalysis), immediate changes in galvanic skin response can indicate that the client is experiencing emotional arousal. It is also used in behavior therapy to measure physiological reactions such as fear. Skin conductance is also a factor in some modern electronics to measure the activation of touchscreen devices. This is notable as many of these devices that use capacitive screens cannot be used while wearing gloves as the sensors are not triggered by the low conductivity of rubber or leather.