The Absolute Threshold of Electric Shock

Thresholds for electric shock were obtained under twelve conditions. Three types of stimulus were used; constant voltage, constant current, and constant power. These, combined with three sizes of electrode, gave nine conditions in all. A further three thresholds were obtained using the three types of stimulus and the medium size electrodes, with the addition of electrode jelly to improve contact. The results indicated that power is the relevant variable, and that sensitivity to threshold shocks probably depends on the amount of power dissipated in the immediate vicinity of the skin receptors. This view is supported by the observation that skin thickness seems to be of considerable importance—the thicker the skin, the higher the threshold. The influence of ambient temperature and humidity were found to be inoperative within the limits investigated. A low skin temperature did, however, raise the threshold. Subjective sensations associated with electric shock are discussed, including an anomalous lowering of the threshold as a result of rapidly repeated strong stimulation. Implications for the use of electric shock as a negative reinforcer in psychological experiments and as an agent in ‘therapy’ are considered. In both cases there would appear to be sound arguments for using a constant wattage a.c. stimulus to counteract the variations in the impedance of a biological circuit

Acoustics · Audiology · Electric shock · Electrical impedance · Electrode · Mechanics · Physics · Stimulation · Stimulus (psychology) · Chemistry · EEG and Brain-Computer Interfaces · Neural dynamics and brain function · Neuroscience · Plant and Biological Electrophysiology Studies · Psychology