Effects of Tactile Stimulation Using an Assortment of Natural Elements on the Psychophysiological Responses of Adults

Abstract

Contact with the natural environment has positive effects on physical and mental health and well-being. This study aimed to investigate the effects of tactile stimulation on the psychophysiological responses of adults, using natural gardening elements. The participants were 30 adults (20–60 years old). The participants received tactile stimulation by touching five natural elements with their hands and feet, and tactile stimulation for each natural element was performed for 90 s. Geranium, tiny ardisia, decomposed granite soil, log hardwood, and culture soil were used as tactile stimulation factors for the hand, and moss, grass, pebble, bark, and culture soil were used as tactile stimulation factors for the foot. Oxyhemoglobin (oxy-Hb) concentrations in the prefrontal cortex during the stimulation as well as blood pressure and pulse rate after each activity were measured. Additionally, the semantic differential method was used to evaluate the psychological effects of contact with the elements on the participants. Compared to before tactile stimulation, the oxy-Hb concentration related to prefrontal lobe cortical activity significantly decreased in some sections using tiny ardisia, log hardwood, and culture soil on the hands, and using grass, moss, pebble, and bark on the feet. Blood pressure also showed a significant decrease after tactile stimulation using geranium, tiny ardisia, and log hardwood. The findings of this study suggest that tactile stimulation using natural gardening elements could be a significant intervention in inducing physiological stability and reducing stress by calming the activity of the prefrontal cortex.