Galvanic Skin Response (GSR) is defined as the change in the electrical properties of the skin. The signal test can be used for capturing the autonomic nerve responses as a parameter of the sweat gland function. The measurement is relatively simple and repeatable, making the GSR assessment a useful tool for examination of the autonomous nervous system function, and especially the peripheral sympathetic system.

Several terms are used for this phenomena, such as EDA (electrodermal activity), EDR (electrodermal response), EDL (electrodermal level), SCA (skin conductance activity), SCR (skin conductance response)  and more.

Galvanic Skin Response can be described in terms of conductance, resistance and electrophysiological potential. The electro-physiological signal is generated by the sweat glands, where sweat is likely the origin of the variation in resistance and conductivity, although vaso-dilatation and constriction may also play an important role.

In most cases, the GSR is measured on areas of skin with high sweat gland concentration. As a reference you can use a part of the skin with fewer or no sweat glands or measure in the same area as the active electrode.

Galvanic Skin Response (GSR)