RESEARCH
The Effects of The Number of Indoor Foliage Plants on Productivity, Stress and Attention
Summary
This study employed a laboratory experiment with a within-subject design to investigate the effects of the number of indoor foliage plants on human productivity, stress, and attention in a simulated workplace environment. Recognizing that previous research on the benefits of indoor plants has shown varied results, potentially due to differences in methodology such as the number and arrangement of plants, this study specifically focused on testing four conditions: a room with no plants, one plant, three plants, and seven plants. Eighteen university students participated, performing a 10-minute English word searching task in a climatic chamber with controlled lighting conditions. Productivity was measured by the number of word search forms and words completed, attention by Secondary Task Reaction Time (STRT), and stress by heart rate change. Subjective perceptions of the room environment were also collected via questionnaire.
The study found no statistically significant differences among the four plant conditions in measures of productivity (number of papers or words), stress (heart rate change), or attention (average STRT or STRT change). While physical environmental factors like temperature and humidity were consistent, CO2 levels showed a near-significant difference (p=0.06), though without a clear relationship to plant number. However, the research did reveal statistically significant differences in subjects’ subjective perceptions of the room. Participants perceived rooms with plants as significantly more friendly, comfortable, fresh, and clean compared to the no-plant condition (p < 0.05). Based on subjective feedback, the room with seven plants was perceived as the best among all conditions. The authors note that the lack of significant findings for productivity, stress, and attention might be influenced by the small sample size and short task duration.
