[Itch and the heat tolerance scale: effects of thermographic biofeedback]

Effects of heat tolerance (HT) relating with individual emotionality, and of thermal biofeedback on itching were examined. Fourteen high HT subjects and 12 low HT subjects were selected by the Cold and Heat Tolerance Scales (Dienstbier, LaGuardia, & Wilcox, 1987). The experiment was divided into three phases: rating of itch, eight thermal biofeedback (increase or decrease) training sessions, and rating of itch with biofeedback. Itching was produced by a glue made from Japanese yam powder. Yam glue was applied on the subjects' dorsal forearm. The biofeedback information was given by the thermographics on the CRT, where its color was changed according to the changes in temperature of the dorsal forearm skin. Results showed that (a) subjects who were instructed to decrease their skin temperature reported comparatively lower intensities of itching, although their actual temperature controls were unsuccessful, and (b) the biofeedback performance reduced the intensity of itching for the low HT subjects, but raised it for the high HT subjects who were instructed to increase their skin temperature. The results suggested that the biofeedback performance could have different central effects on itching among the HT groups.