Psychological and Physiological Effects in Humans Induced by the Visual and Olfactory Stimulations of an Interior Environment Made of Hiba (Thujopsis dolabrata) Wood

To investigate the visual and olfactory effects of an interior environment made of hiba (Thujopsis dolabrata Sieb. et Zucc.) wood in humans, we measured psychological and physiological responses. Four actual-size model rooms containing different proportions of hiba wood were constructed for this experiment. Subjects were 14 healthy male and female college students. Changes in psychological evaluations and physiological responses were examined after entering each of these rooms. As a result of an analysis of volatile compounds in the indoor air after the experiment, air concentration of sesquiterpenes was increased by increasing the amount of hiba wood in the interior environment. Odor intensity and acceptability were significantly increased by increasing the amount of hiba wood in the interior environment. A room with hiba wood used for the floor and walls felt significantly more natural and traditional than a room without hiba wood, and changes in the fatigue level on profile of mood states (POMS) were significantly less in a room with hiba wood used for the floor and walls than those in a room without hiba wood. Blood pressure and salivary alpha-amylase findings suggested that differences in the amount of hiba wood in the interior environment caused different levels of autonomic nervous activity. Therefore, there was no correspondence between psychological evaluations and physiological responses.