This research was aimed at analyzing functions of trees at spaces of highway-rest-areas. The experiment was conducted at Sayama Parking Area, Sayama, Saitama prefecture in Japan. 20 students participated in this study to measure their physiological and psychological responses to 8 different scenes of shops and parking lot with large trees approximately 440cm in height, middle trees, approximately 180cm in height, shrubs approximately 70cm in height or no planting. During the exposure time of eye movements, heart rate and heart-rate-variability were recorded as well as near-infrared spectroscopy were used to measure the brain activity. The participants were asked to describe their impressions by the semantic differential questionnaire. The results showed that middle trees had effects that attract participant's eyes on trees and increase the cerebral activity in the association area and so on. Participants felt scenes with middle trees comfortable, vigorous and so on. These results suggested middle trees brought participants into a refreshed state. The cerebral activity of participants looking at parking lot with large trees was sedated in the association area and so on as well as participants felt comfortable, calm, secure and so on. These results suggested large trees brought participants into a relaxed state.
