Electrodermal activity

Electrodermal activity (EDA) is the property of the human body that causes continuous variation in the electrical characteristics of the skin.

Sweating is controlled by the sympathetic nervous system,[4] and skin conductance is an indication of psychological or physiological arousal.

Hermann later demonstrated that the electrical effect was strongest in the palms of the hands, suggesting that sweat was an important factor.

[7] Vigouroux (France, 1879), working with emotionally distressed patients, was the first researcher to relate EDA to psychological activity.

One of the first references to the use of EDA instruments in psychoanalysis is the book by C. G. Jung entitled Studies in Word Analysis, published in 1906.

[15] The controversial Austrian psychoanalyst Wilhelm Reich also studied EDA in his experiments at the Psychological Institute at the University of Oslo, in 1935 and 1936, to confirm the existence of a bio-electrical charge behind his concept of vegetative, pleasurable "streamings".

[16] By 1972, more than 1500 articles on electrodermal activity had been published in professional publications, and today EDA is regarded as the most popular method for investigating human psychophysiological phenomena.

Instead, it is modulated autonomously by sympathetic activity which drives human behavior, cognitive and emotional states on a subconscious level.

[19] Human extremities, including fingers, palms, and soles of feet display different bio-electrical phenomena.

These autonomic sympathetic changes alter sweat and blood flow, which in turn affects GSR and GSP (Galvanic skin potential).

Galvanic skin potential (GSP) refers to the voltage measured between two electrodes without any externally applied current.

Another common manifestation is the vasodilation (dilation) of blood vessels in the face, referred to as blushing, as well as increased sweating that occurs when one is embarrassed.

[23] EDA is a common measure of autonomic nervous system activity, with a long history of being used in psychological research.

[21] The E-meter used by the Church of Scientology as part of its practice of "auditing" and "security checking", is a custom EDA measurement device.

Internal factors such as medications and hydration can also change EDA measurements, demonstrating inconsistency with the same stimulus level.