Physiological and psychological responses to tended plant communities with varying color characteristics

Exposure to plants has been reported to promote health and reduce stress, and plant color has direct impacts on physical and mental health. We used images of common types of tended plant communities in Shenyang, China, with combinations of yellow, green, and red foliage, as experimental stimuli. A total of 27 images were used as visual stimuli. We used electroencephalography to measure α wave activity (8–13 Hz) in 40 subjects while they viewed visual stimuli. These data were combined with subjective questionnaire data to analyze the relaxing effect of images of tended plant communities with different color types and proportions on people. The results revealed that, although there were slight differences between the electroencephalography and psychological findings, women were significantly more relaxed than men after viewing the images. Physiological and psychological responses varied with the types and proportions of colors in the tended plant communities: those of foliage with combinations of two or three colors induced stronger responses than images with a single color. Specifically, (1) for one-color plant communities, green or yellow plant communities induced a stronger relaxation effect than red plant communities; (2) for two-color plant communities, the optimal color proportion was 55% + 45%, and the green + yellow and green + red color combinations induced a stronger relaxation effect; (3) for three-color plant communities, the relaxation effect was strongest when the color proportion was 55% green + 25% yellow + 20% red. These data would provide a plant color matching in future plant landscape design, which may be helpful for creating healthy and relaxing environments. Graphical abstract