Studies on the diphasic wave form of the galvanic skin reflex.

Abstract The galvanic skin reflex at the palm and the dorsum of hand were investigated on 27 human subjects, changing room temperature and local skin temperature mainly in order to study the mechanismunderlying the appearance of the diphasic potential GSR curve. Experimental factors which might cause the wave form distortion of the potential GSR curve were carefully excluded in the performance of the experiments. Simultaneous recording from the palm and the dorsum of hand was applied so as to enable a comparison of the results with each other. 1. (1) With the rise of skin temperatures as a result of increasing room temperature or of local warming, the potential GSR curve at the dorsum of hand as well as the palm showed shorter latency. 2. (2) At the low room temperature of 15°C, the GSR failed to appear in high percentage (67.0 per cent) at the dorsum of hand, while monophasic GSR curve was observed most frequently (53.8 per cent) at the palm. 3. (3) With the rise of room temperature, it became easier to cause the GSR to appear at the dorsum of hand and the percentage of diphasic GSR curves with deeper positive deflection (type d ) continued to increase until the room temperature reached 40°C (from 0.8 to 95.2 per cent). The situation at the palm was different from this: the diphasic GSR curve with deeper positive deflection (type d ) increased in percentage until the room temperature of 30°C (from 24.5 to 52.8 per cent), above which it decreased markedly (8.2 per cent at 40°C); then monophasic wave form increased again. These phenomena at the palm might be attributable to the suppressed mental sweating on the palm at higher room temperature which was found by Kuno (1956). 4. (4) By means of local warming, it was possible to make shorter the latency of the GSR both at the palm and at the dorsum of hand and to elicit more frequently the diphasic potential GSR curve with deeper positive deflection. However, the change of the wave form from diphasic to monophasic of the palm as was observed at higher room temperature, was not caused by local warming even when the skin temperature of the warmed area was raised up to 40°C. This might suggest that the suppression of the GSR at the palm at higher room temperature is due to some central mechanism. 5. (5) The rationality was discussed of classifying the wave form of the potential GSR curve into four types according to the depth of its positive deflection in order to express the intensity of reflex activity.