Abstract
Why do plants or photos of plants make a room more attractive?
Real plants are used in rooms because they add color, brightness, texture, and life to rooms; but what about photographs? Photographs of plants can still add color and brightness to a room. Careful selection of color schemes is important, as some colors can affect the mood of the observer. In 1973, Adams and Osgood 3 interviewed people from 23 cultures about how colors made them feel. Red gave the most universal associations of strength, vitality, and activity; white, blue, and green were generally ranked as “good”; and yellow was “weak.” This study gave a ∼ 70% rate of agreement and was the basis for modern color psychology. Horticulturist Dr. William Johnson 4 recently wrote about the effect of different colored blooms in the Galveston County Daily News: “Red and yellow flowers, for instance, are instant attention-grabbers. However, it's been found that men tend to favor yellow-based reds (like scarlet), while women tend to favor blue-based reds (like burgundy).” Blue flowers have a calming effect, according to Johnson. He adds: “When it comes to choosing blues, lighter hues are preferred over darker ones, if you want to send a message that promotes relaxation. White blooms send a message of cleanliness, orderliness, and precision. Mixing textures and adding other colors in with a white floral arrangement can help to soften a clinical feel.” So according to the experts, light blue and white flowers would be best for reducing anxiety.
Another way that plants could make a room more attractive is by improving indoor air quality. They add oxygen to the room's air by the process of photosynthesis, and they also add humidity to the air via transpiration. A team of National Aeronautics and Space Administration researchers, led by Wolverton, tested the effect of fifteen houseplants on three pollutants known to be present in spacecraft. 5 These same three pollutants—benzene, formaldehyde and trichloroethylene—are present in homes. Under controlled conditions, in the NASA study, certain houseplants were found to remove as much as 87% of indoor air pollutants within 24 hours. However, that does not explain the finding by Beukeboom et al. that photographs of plants were just as effective as real plants in reducing patient stress.
How else can plants or photographs of plants reduce patients' stress besides making a room more attractive?
Plants represent part of the original ecosystem in which humanity evolved. Plant species, as we know them today, have been around for some 150 million years. Human evolution only started 4.5 million years ago, and produced Homo sapiens ∼ 100,000 years ago. Our entire evolutionary history was therefore closely linked to nature, but industrial development has effectively isolated city dwellers from close contact with nature for a large proportion of their daily life. In the mid 1980s, Harvard biologist, E. O. Wilson, introduced the biophilia theory, which suggests that human beings thrive in nature and suffer in its absence. 6 The term “biophilia” literally means “love of life or living systems.” The biophilia effect theory states that environments rich in views and imagery of nature can reduce stress and increase focus and concentration. The theory describes “the connections that human beings subconsciously seek with the rest of life.” Wilson proposed the possibility that the deep affiliations humans have with nature are rooted in human biology. The biophilia theory would explain why indoor plants help people feel less anxious in hospital waiting rooms. The plants provide a link to the environment in which humanity evolved.
Why do photographs of plants work just as well as real plants?
Perhaps the reason that photographs of plants work as well as real plants is that plants affect us through a deep psychologic mechanism so powerful that it can be mediated just by the symbol “plant” without a need to experience the real thing. James Wise suggests that such symbols are really mathematically defined fractal patterns. 7 Fractals are geometrical complex shapes that appear to repeat at finer scales, as often observed in nature; for example a branch from a tree or a frond from a fern. Wise believes that the beneficial effects of nature can be produced by fractals alone without the need for actual images of nature. This idea is consistent with the finding that photos of plants in the hospital waiting room were just as effective as photos of plants for reducing patient anxiety.
Can other aspects of nature work just as well as plants?
For almost 2 million years, human beings lived on the savannahs of Africa, and then of Europe and Asia; vast, parklike grasslands with lakes and rivers, dotted by groves of scattered trees. According to the biophilia theory, other aspects of nature, such as water and rocks, should work just as well as plants in reducing anxiety. 6 One study supports this hypothesis. In this study 166 patients who had undergone open-heart surgery were shown one of 4 types of pictures. The patients who were shown a nature picture dominated by water had significantly less postoperative anxiety than the patients who were shown a nature picture dominated by trees, or an abstract picture, or no picture at all. 8
To summarize, there is much evidence, as provided by Beukeboom et al. and by other authors cited in their article, that just placing photographs of plants on the walls of hospital waiting rooms will significantly reduce patient anxiety. Patients feel that photographs of plants enhance the attractiveness of the waiting room, but it is not clear exactly why this happens. Although photographs may add some color to the room, this is unlikely to account for the observed psychologic effect on the patients. The theory of biophilia explains why photographs of plants help people feel more comfortable and relaxed in terms of connecting them to the environment in which humanity evolved. 6 Awakening the bond between humanity and nature is especially important in the medical environment, because it often appears to be harsh and bereft of nature.