Abstract
The purpose of this study was to find a strategy to isolate two different effects on the skin temperature (ST) biofeedback training: an active treatment effect and a placebo effect. The experimental group consisted of 41 college students, who volunteered for this study. Other 7 students served as subjects for the control group. The experimental subject met for the training one or two sessios weekly for two months. One session included a series of 10 trials of 110 seconds each with a pause of 20 seconds in between. The training goal was to increase the ST above 90°F on the index fingertip of the left hand monitering by the Bi-tone Derivation Feedback Mode. In this Mode a low-pitched tone was presented whenever the temperature was in creasing, and a high-pitched tone was preseted whenever the temperature was decreasing. This mode was regarded as the normal signal. Two months later, 16 of the experimental subjects and the 7 control subjects participated in the experimental test, which was designed to compare the two groups in terms of the placebo effect using three kinds of feedback signal : a normal signal and two false signals (a reversal tone and a random tone). The subjects were always blind to the randomized presentation of the three signals. According to the obtained data, none of the control subjects were able to increase the ST (Fig. 1), whereas 8 proficient subjects among the 16 experimental subjects were able to increase the ST consistently above 94°F, regardless of the false feedback signals (Fig. 3). Though the remainder of the 16 experimental subjects were able to increase the ST at a higher level tharn the control group, they failed in the self-control due to the influence of pseudo-feedback (Fig. 2). The results suggests that the startegy adapted in the present study can be an effective measure of the placebo effect in the ST biofeedback training.
