Conrolled Physical and Subjective Intensities of Electric Shock

ABSTRACT A series of investigations was conducted to determine which physical parameters must be controlled to deliver constant electrical stimulation and the effect of controlling these parameters on subjective estimates of shock intensity. Constant voltage and constant current stimulation were tested with eight waveforms and five electrode configurations, including a concentric disc electrode. Dry skin and treated skin techniques were tested in a comparative power experiment and with a method of magnitude estimation. Passing an electrical stimulus through an electrode‐skin circuit produces a marked reduction in the impedance of that circuit. This drop in impedance is a local effect, rather than a centrally mediated response, causes differences in perceived magnitude, and occurs no matter whether voltage, current, or power is held constant and no matter what waveform, frequency or electrode configuration is used. The use of the concentric disc electrode and treatment of the skin with an electrolyte makes it possible to reduce impedance to a predetermined level, which when combined with constant voltage or constant current results in a constant physical stimulus and constant subjective estimates of the stimulus intensity.