MASTER PROJECT

Phytophilia: Effects of natural and artificial foliage plants on human cognitive performance and cortisol levels from an evolutionary point of view

The aim of my study is to show that the positive effects of plants on human cognition, test performance and stress coping is partly induced by evolutionary adaptions.
During the evolutionary past the human being lived most of the time in the savannas of tropical Africa. In these regions green plants were presumably very important for our ancestors because they indicated food, water and protection. For this reason modern humans still seem to have a predisposition for plants, what is called phytophilia (Ulrich 1983). One explanation is that the human brain is better adapted to natural than urban environments and therefore it needs less working capacity in a natural surrounding (Wohlwill 1983). Furthermore, the optical stimulation by foliage plants results in less stress due to the release of the cognitive apparatus of the individual (Ulrich 1979).
The positive effects of the presence of plants on human cognition could be demonstrated in several studies. Shibata and Suzuki (2002) for instance found that men facing plants were better in a creative word-association-test than men without plants. In the work of Lohr et al. (1996) the presence of plants clearly correlated with an improved reaction rate of the test persons. Oberzaucher (2000) studied examinees taking the theoretical driving license test. She could prove that candidates are positively influenced by green plants positioned next to their PC workplaces they had to use during the test. The examinees with plants in the room performed much better and more effective than those without.
In the current work I used the experimental design of Oberzaucher (2000) and added a third test condition with artificial plants. Like in the former study the examinees of the theoretical driving license test were my tested subjects. Living Ficus-trees, artificial plants of similar appearance and conventional items in green colour (green model cars) were used and placed next to every computer screen in the examination rooms. In addition, I collected physiological data from every test subject in the form of saliva-samples to measure levels of the stress-related hormone cortisol.
The experiment took place from July to October 2006. I tested more than 500 examinees. Analysed data are not available yet.