Abstract
The scientific substantiation of skin treatment efficacy is one of the most important recent tasks for cosmetic scientists. Skin treatment is generally expected to produce psychological effects in addition to dermal physiological and physical effects.
The purpose of this study was to quantitatively measure one aspect of psychological effects, mental relaxation, for substantiating the effects of skin treatment.
For this purpose, we tried to apply some methods of Bio-feedback for Self-control used in Psychosomatic Medicine. From preliminary experiments we chose galvanic skin resistance (G. S. R.) method as the primary measuring method because of its high sensitivity and good reprodubibility. The principle of this method, which is widely recognized in medical field, is based on measuring the variation of G. S. R. of fsngertips, caused by mental perspiration. In our work, G. S. R. was measured with a commercial instrument, but the sensors attached to the skin, the voltage controller and the recorder were modified for higher sensitivity. The G. S. R. sensors were attached to forefinger and middle finger of right hand, and sensors of dermal blood flow (D. B. F.) and pulse wave (P. W.) to fingers of left hand of subject. In order to detect only the effect of skin treatment, measurements were made while the subject was sitting on a chair under normal lighting in a constant temperature and humidity room, without background music.
To study the mental relaxation effects of the skin treatment, we measured the variation of G. S. R., D. B. F., and P. W. in fingertips of about 30 women while their faces were being massaged with varying degrees of pressure with and without using a cold cream. The degrees of massaging pressure were previously determined by an original method, and standardized into 3 grades corresponding to weak, normal and stronge pressure. After massaging for 3 minuits, each subject was inquired to determine the state of mental relaxation using a 4 step evaluation.
G. S. R. of the fingertips of subject whose face was being massaged with a use of a cold cream gradually increased. Statistically, the largest difference in the G. S. R. value was observed before and after the treatment using a cold cream and normal massaging pressure. This difference of G. S. R. value was greater than treatments with weak or strong pressure, or the treatment without using a cold cream. These results correlated well with self-evaluations of mental relaxation. The results of D. B. F. and P. W. data did not show as clear correlation as G. S. R. data.
By using this technique, we were able to substantiate the mental relaxation efficacy of massage treatment by using a cold cream, and evaluate several massaging techniques. Moreover, the technique enables us to study other psychological effects of different cosmetics.
