Abstract
We aim to provide cosmetics that appeal to users' “sensibility” and have accordingly developed cosmetics based on a sensibility evaluation. As the research subject, we chose exfoliating lotions. Our method correlates the visualized psychological structure with measured physical quantities. To visualize the psychological structure when using an exfoliating lotion, we selected appropriate evaluation words and conducted a one-month usage test. Using factor analysis, we evaluated nine factors that are related to the value judgments of users using the exfoliating lotions. Next, we analyzed the causal relationships between these factors via structural equation modeling and modeled the psychological structures of the users. The model fit indices were satisfactory. The subconsciously important perceptions appeared to be “frictional feeling” and “wiped-off feeling,” both of which are derived from the tactile impression imposed by the wiping motion. Next, to identify physical quantities that can independently affect the “frictional feeling” and the “wiped-off feeling,” we measured the dynamic friction coefficient and the time profile of the frictional force for 12 types of exfoliating lotions. Using the dynamic friction coefficient, the two factors could not be individually evaluated; On the other hand, we extracted the eight-dimensional vibrational feature quantities in the time-frequency domain from the time profile and correlated them with the factor scores of the two factors in a multiple regression analysis. The factor scores were estimated with high accuracy. Each factor corresponded to a different vibrational feature, confirming that the factors are physically independent. This result suggests that both factors can be simultaneously increased by controlling the frictional force. Using this result as a predictive index of the tactile impression, it was possible to do sensibility evaluation of an exfoliating lotion that had a superior texture at the time of wiping; this could not be achieved in the past.
