Investigations into the benefits of nature to humans should consider how such benefits are delivered through the full range of our sensesResearch on the human benefits of nature tend to focus on the visual aspects of nature experiences. This review examined the evidence of nature benefits delivered through our lesser-studied sensory pathways (sound, smell, taste, and touch) and three non-sensory pathways (phytoncides, negative air ions and microbes). This research also identified important gaps in our understanding of how nature experiences benefit human health and well-being and offers suggestions for further investigations. Nature, for purposes of this review, includes phenomena as varied as landscapes, microorganisms, and pets. It also includes nature simulations.
Benefits associated with viewing nature include reduced anxiety and stress, shorter hospital stays, lower heart rate, and increased directed attention. Benefits associated with hearing the sounds of nature (in both real and virtual settings) include restoration and place attachment -- both of which may be linked with positive feelings about the environment. Nature-related scents – which include both pleasant and unpleasant odors –can affect our mood, behavior, and cognition. Some unpleasant odors provide warnings, as in the case of spoiled meat. Taste -- the least explored sense in the literature – impacts emotions as well as physical health. Organic food is perceived as tasting better and making one feel better than food that is not organic. Research indicates that more natural diets are better for our physical and mental health, and that growing your own food has positive effects on individuals and communities. Research on the benefits of tactile experiences with nature includes investigations into the benefits of hands-on experiences of children in forest schools. These benefits include improved skills in cognition, social interaction, physical development, motivation, and concentration. Tactile experiences with animals are associated with improved physical and mental health for both children and adults. Some such benefits remain over time.
Phytoncides – a non-sensory pathway impacting human health – are organic compounds emitted by plants and ingested through inhalation. The practice of “shinrin-yoku” or “forest-bathing" is based on the known health benefits of phytoncides, which include increased immune system activity in vitro, decreased stress, and increased relaxation. Negative air ions – particularly abundant in natural places -- represent another non-sensory pathway impacting human health. In addition to killing bacteria, air ions are also associated with positive physiological and behavioral changes in people. Microbes – the third non-sensory pathway discussed in this review – are typically found in the gut with likely health benefits in terms of both prevention and treatment of illnesses.
This review highlights the need for more research on the different pathways through which humans can experience the health and well-being benefits of contact with nature. Suggestions for planning and conducting such research are offered.
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