These timing characteristics make the GSR evoked potentials significantly different from classic event related potentials (ERPs) in the context of electroencephalography (EEGClosed). The typical waveform is a composition of endogenous (1-5 spontaneous fluctuations/min) and evoked activityĪ time-to-peak in the order of seconds is expected for evoked potentials.
Physiological values are usually in the 1-30 µS range, however, significant inter-subject variability is to be expected within this range.
The GSR signal is measured in µS (Siemens, physical unit of electric conductance). It is used together with surface electrodes that are in contact with the skin of the test subject. The GSR module converts the electric conductance of the skin to a voltage recorded by a bipolar amplifier input (AUXClosed Port). This means that a constant voltage of 0.5 V is applied in order to acquire the skin conductance, according to published recommendations. The Brain Products GSR module uses the exosomatic recording principle with direct current (DCClosed). The GSR signal can therefore be used to gain an insight into the emotional state, or arousal, of the subject under specific experimental conditions. Skin conductance is modulated by sympathetic activity and is not under conscious control. Most commonly measured are skin conductance level (SCLClosed) and skin conductance reaction (SCRClosed). Galvanic Skin Response (GSRClosed) and Electrodermal Activity (EDAClosed) are the collective names for electrical phenomena of the skin. Significance, measurement principle and signal properties of the GSR signal Significance
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