Galvanic skin response
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 is conducted by attaching two leads to the skin, and acquiring a base measure. Then, as the activity being studied is performed, recordings are made from the leads. There are two ways to perform a GSR - in active GSR, current is passed through the body, with the resistance measured. In passive GSR, current generated by the body itself is measured.
GSR originated in the early 1900s. It was used for a variety of types of research in the 1960s through the late 1970s, with a decline in use as more sophisticated techniques (such as EEG and MRI) replaced it in many areas of psychological research. GSR still sees limited use today, as it is possible to use with low-cost hardware (galvanometer).
GSR measurement is one component of polygraph devices and is used in scientific research of emotional arousal.
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.