Galvanic Skin Response GSR for Academic Research Proposals - EEG Brain Products
Galvanic Skin Response module (GSR module)
Significance, measurement principle and signal properties of the GSR signal
SignificanceGalvanic Skin Response (GSR) and Electrodermal Activity (EDA) are the collective names for electrical phenomena of the skin. Most commonly measured are skin conductance level (SCL) and skin conductance reaction (SCR). Skin conductance is modulated by sympathetic activity and is not under conscious control. The GSR signal can therefore be used to gain an insight into the emotional state, or arousal, of the subject under specific experimental conditions.Measurement principleThe Brain Products GSR module uses the exosomatic recording principle with direct current (DC). This means that a constant voltage of 0.5 V is applied in order to acquire the skin conductance, according to published recommendations.The GSR module converts the electric conductance of the skin to a voltage recorded by a bipolar amplifier input (AUX Port). It is used together with surface electrodes that are in contact with the skin of the test subject.Signal propertiesThe GSR signal is measured in µS (Siemens, physical unit of electric conductance). Physiological values are usually in the 1-30 µS range, however, significant inter-subject variability is to be expected within this range. The typical waveform is a composition of endogenous (1-5 spontaneous fluctuations/min) and evoked activity.
GSR set (non-MR): electrode pair with 70 cm long cable (left), GSR module (middle), GSR-specific gel TD-246-4 (right).