Changes in emotional state while holding a slimy fluid in the palmar skin

摘要

© 2021. The Japan Society of Mechanical EngineersVarious effects have been observed when a slimy fluid is held in palmar skin. The observed effects include friction control of the skin and cleansing and moisturizing of the skin. However, few reports exist regarding the changes in the emotional state of persons when a slimy fluid is held in their palmar skin, even though the viscosity properties of the fluid affect emotional changes. Thus, this study investigates the emotional changes due to holding slimy fluid in the palmar skin by evaluating heart rate variability (HRV) and sensibility. Newtonian and non-Newtonian fluids, with viscosities ranging from 0.01 to 100 Pa·s, were prepared. Eight male subjects in their 20s soaked their palms in the slimy fluid without seeing it. At the room temperature of 25 °C, the subjects moved their palms freely for 1 min. They were allowed to rub their palms together. During the experiments, the HRV was recorded. A frequency analysis was performed for estimating autonomic nerve activity. After holding the fluid, the subjects were asked to provide feedback through the semantic differential method. Significant changes in autonomic nerve activations were observed when the subjects soaked their palms in the slimy fluid. The high viscosity Newtonian fluid reduced the parasympathetic nervous system activity. These changes in the psychophysiological indexes influenced the feelings of the subjects ascertained according to the semantic differential method. A relationship between the characteristic of the slimy fluid and a psychophysiological index can improve the efficiency when developing products exposed to human skin.