Perceived locus and intensity of electrocutaneous stimulation

Two experiments are described which investigated the perceived locus and intensity for electrocutaneous stimulation. In the first experiment, 21 subjects reported the perceived locus for various combinations of four electrode sites, two current directions, two pulse characteristics (single versus multiple), and two sensation levels (detection versus pain). In the second experiment, 16 subjects reported the perceived locus and intensity for a wide range of current levels and two polarity conditions. The main results were the following: (1) sensations were likely to be perceived under the cathode at detection levels, but under both electrodes at intense levels; (2) the cathode localization was gradually supplanted by anode and cathode localization with increasing current; (3) subjective intensity under the cathode was greater than that under the anode; (4) the effects of cathode position on perceived locus were found for only some pairs of electrodes. These results challenge the simple hypothesis that electrical stimulation of the skin through paired electrodes is perceived under the cathode.