Growing interest in the relaxation effect of nature has elicited demands for scientific verification of the various natural elements. This study investigated the physiological and psychological responses of 27 females in their 20 s to viewing a waterfall and urban images (control) presented via a large, high-resolution display for 90 s. High-frequency [HF] for parasympathetic nervous activity and the ratio of low-frequency (LF)/[LF + HF] for sympathetic nervous activity by heart rate variability and heart rate were recorded. Simultaneous changes in oxyhemoglobin concentration in the prefrontal cortex were recorded by near-infrared time-resolved spectroscopy. The modified semantic differential method and Profile of Mood States Second Edition were used to assess the psychological effects on the participants after viewing each image. The results showed that viewing the waterfall image, compared with viewing the urban image, (1) increased sympathetic nervous activity; (2) provided comfortable, relaxed, and natural impressions; (3) improved mood states. In conclusion, visual contact with a waterfall image physiologically activated sympathetic nervous activity and psychologically evoked positive moods and feelings.

Existing studies have demonstrated the restorative benefits of being in forests. However, most studies have designed participants to engage individually in forest walking and viewing, which neglects the social aspect of conversation. Researchers suggested that social context should be studied in order to have a better understanding how forests foster human health. To this end, we examined the role of social context using three types of forest therapy programs: a guided program, a self-guided program, and a walk alone program. A between-subject, pretest-posttest field experimental design was employed to evaluate restorative effects by measuring the physiological responses and mood states incurred in different forest therapy programs. Our findings showed, that the walk alone group exhibited a significant systolic blood pressure decrease and a significant increase in sympathetic nervous activity; the self-guided group showed a significant increase in heart rate values and significant decreases in systolic blood pressure and diastolic blood pressure; and the guided group revealed a significant decrease in systolic blood pressure. Further, the three forest therapy programs had positive effects on improving mood states, except a nonsignificant vigor-activity increase in the walk alone group. The three programs did not exhibit significant differences in changes of restorative benefits in physiological and psychological measures except for a significant difference in changes in sympathetic nervous activity between the walk alone group and guided group. The results showed the restorative benefits of forest therapy are apparent regardless of the program type. The management team should continue promoting forest therapy for public health by providing different types of forest therapy programs and experiences.

Visual characteristics (e.g., the color and shape) of ornamental plants can significantly affect their beneficial influence on humans. Prior research, however, has largely focused on the effects of the color or shape of flowers and the impact of differences in the visual appearance of foliage plants and plants with ornamental stalks has not yet been fully explored. This study examined the psychophysiological effects of urban ornamental bamboos that expressed different colors on different organs. Three hundred Chinese college students participated in the experiment. They were randomly assigned to view images of five ornamental bamboo landscapes with the following different visual characteristics: green stalks (GS) non-green stalks (NGS) multicolored stalks (MS) green leaves (GL) and multicolored leaves (ML). Before and after viewing the images, their EEG, blood pressure, pulse, profile of mood states (POMS) score, and state-trait anxiety inventory (STAI) score were measured. The results showed that ornamental bamboo landscapes have extremely significant beneficial psychophysiological effects as compared to urban landscapes. After viewing landscapes in the NGS and MS groups, EEG, blood pressure, and pulse rate of subjects showed more beneficial changes. Significant gender differences were observed only in systolic blood pressure and in the vigor score. In addition, an extremely significant interaction between color and organ of color expression was observed on systolic and diastolic blood pressure. Organ of expression had significant main effects on all the physiological indicators and the fatigue, vigor, and irritability scores, while color only had a main effect on systolic blood pressure. Our study concluded that viewing urban ornamental bamboo landscapes with different visual characteristics has different effects on humans. With regards to ornamental bamboo, the organ expressing the color had a greater impact on psychophysiological responses than did the type of color itself. These study results can provide guidance for landscape construction of urban greening.

This study illustrated the physiological and psychological effects of watching videos of different durations showing bamboo forests with varied structures. Physiological indicators, including EEG (electroencephalogram), blood pressure, skin conductance, and pulse, were monitored in 180 Chinese university students (mean age: 20.72 ± 2.56 years) while they were watching bamboo videos. Before and after watching the videos, their psychological indicators, including positive and negative moods, were measured using the Profile of Mood States questionnaire. After watching the bamboo videos of different durations, all of the physiological indicators responded to the stimulation after only 1 min. The indicators showed different trends at 1, 3 and 5 min. EEG decreased and then was maintained at a stable level after 1 min, and the high β, low β, and α waves had no significant differences between 1, 3 and 5 min. Blood pressure dropped to a stable state after 3 min, and the decline was significantly different greater after 3 min than after 1 min. Skin conductance increased for 1 to 5 min, and it did not stabilize after a long time (5 min). Pulse decreased after 1 min but increased after 5 min. After watching the videos with bamboo of varying structures, the physiological and psychological indicators showed significantly different changes. Skin conductance significantly increased (mean value: 6.78%), and the amount of sweat was more effectively reduced, thereby reducing tension, when the students viewed videos of sympodial bamboo forests compared with monopodial bamboo forests. Bamboo forests with a higher canopy density (0.83-0.85) could significantly decrease α waves (mean value: 1.50 Hz), relaxing the human body. High β and low β waves showed greater decreases, with tension reduced more effectively, when bamboo forests with a low tilt ratio (< 1.5%) were viewed. Bamboo forests with neat undergrowth could have more beneficial physiological and psychological effects on the human body.