Physiological benefits of viewing nature: A systematic review of indoor experiments
Physiological responses to viewing nature support the usefulness of nature therapy for preventive medicine
The academic literature includes a number of studies focusing on the health benefits of engagement with nature. Findings from this body of research indicate that even representations (e.g., photos, videos, etc.) of natural environments or natural elements can promote human health. Most of this research is limited to engagement through visual stimulation versus engagement of the other senses. “The present study aimed to understand the entirety of this research domain and to review the potential of nature therapy as a type of preventive medicine.”
The studies included in this review presented evidence of the physiological effects of viewing nature based on indoor setting experiments, using real elements or representations of nature as visual stimuli, and were published in peer-reviewed journals. Thirty-seven studies met these review criteria. All were published between 1970 and August 2019. The studies were analyzed for (1) their visual stimulation method (photos, videos, real natural elements, etc.); (2) the physiological measures applied (functional magnetic resonance imaging, electroencephalography, salivary cortisol concentration, etc.); (3) groups of participants (based on age, gender, etc.), and (4) outcomes (physiological effects). Organization of the studies in this review is by type of nature exposure such as forests, flowers, and wood. Studies using nature images (or videos) investigated the physiological effects of viewing a range of natural landscapes (forests, urban green spaces, mountains, bodies of water). Studies using real natural elements investigated the physiological effects of viewing indoor green plants, flowers, and wooden materials.
The majority of the studies that used representations of natural elements found that viewing natural scenery led to more relaxed body responses than viewing images with no natural scenery. Studies that used real natural stimuli (flowers, green plants, wooden materials) reported positive effects on cerebral and autonomic nervous (involuntary) activities compared with stimuli without real natural elements. Evidence of the restorative effects of viewing representations of natural elements included a deactivation of the visual and attentional areas of the brain and a reduction in eye blinking. Some evidence indicated that an urban green landscape scene without people was more restorative than a similar scene with people. Evidence also showed that nature-based components in a landscape scene were more likely to reduce stress than hardscape (built) components in the scene. There was also evidence of gender being a factor in producing different physiological and relaxation effects when viewing urban green space. One study, for example, reported that the diastolic blood pressure of males decreased when viewing garden landscapes, whereas for females there was an increase in their diastolic blood pressure for garden scenes. Positive outcomes of viewing images or real elements of nature also included improvements in the recovery process following a stressful event, improved concentration of elementary students, and improved recovery time for surgery patients. Brain imagining results showed that different landscapes affected regional brain activity differently. For example, one study found that the visual and attention areas of the brain responded differently to images of urban and natural environments, with some indications that “a nature-oriented lifestyle is inherently preferred.”
The overall results of this review indicate that humans tend to experience positive physiological responses to viewing images of natural landscapes or real natural elements. “These findings have strengthened and deepened the growing evidence base on the health benefits of nature.” These findings also support the potential of nature therapy as making a valuable contribution to preventive medicine.
Citation
Jo, H., Song, C., Miyazaki, Y., (2019). Physiological benefits of viewing nature: A systematic review of indoor experiments. International Journal of Environmental Research and Public Health, 16
