On this page you will find examples of experimental research that have been conducted.  Each article has a summary and a link to the article can be accessed through clicking on the title.

Assessing and Influencing Attitudes Toward Water Conserving Landscapes
SUMMARY: Implementing water-conserving landscapes is one action that many individuals can take to help ease the nation’s water crisis, but few people seem to be exercising this option. Some horticulturists attribute this to a negative attitude toward such landscapes. Our research was designed to assess these attitudes and to see if they could be improved with information. Questionnaires were administered to people in treatment or control groups. Those in the treatment group viewed a short videotape about water issues and water-conserving landscapes. Initial attitudes in both groups were neutral or positive, not negative as predicted. Viewing the videotape was associated with significantly improved attitudes. People in the treatment group described water-conserving landscapes as less hot, more colorful, and more attractive three weeks after viewing the videotape than they had initially.

Effects of Floral and Foliage Displays on Human Emotions
SUMMARY: Changes in human emotions were investigated during exposure to three different indoor conditions: floral display present, foliage display present, and no display present. There were 20 subjects (10 males and 10 females) in each condition. The subjects were shown a video that introduced the University of Reading and included scenes of landscapes. It was shown that a floral display had positive effects on human emotions, such as composition and confidence, however, some evidence of a significant increase in annoyance was also found for this treatment. The foliage display had a somewhat negative effect by slightly increasing bad temper, and the foliage display tended to have a positive effect on clear headedness. Investigations of psychological responses to nature are complex, and many opportunities for more work exist.

Influences of Foliage Plants on Human Stress During Thermal Biofeedback Training
SUMMARY:Twelve 20-minute thermal biofeedback sessions were conducted with 26 university students. Visual stimuli were provided by a living foliage plant, a life-sized color photograph of that plant, or a metal stool (control). Of the participants, 38% responded positively to the presence of a live plant or plant photograph, while 23% showed lower stress in the control room. Stress reduction, as indicated by higher skin temperatures, occurred within the first 5 to 8 minutes of a 20-minute thermal-biofeedback session. A non-plant visual stimulus was not part of the experiment. The results are not intended as comparative nor do they attribute unique or superior effects to plants.  Due to the small number of participants, no significant results were obtained, but the trends were important and are being reported to help further research in this area.

Interior Plants May Improve Worker Productivity and Reduce Stress in a Windowless Environment
SUMMARY:This study documents some of the benefits of adding plants to a windowless work place-a college computer lab. Participants’ blood pressure and emotions were monitored while completing a simple, timed computer task in the presence or absence of plants. When plants were added to this interior space, the participants were more productive (12% quicker reaction time on the computer task) and less stressed (systolic blood pressure readings lowered by one to four units). Immediately after completing the task, participants in the room with plants present reported feeling more attentive (an increase of 0.5 on a self-reported scale from one to five) than people in the room with no plants.

Physical Discomfort May be Reduced in the Presence of Interior Plants
SUMMARY:A well-known research report showed that being in a hospital room with a view of trees rather than a view of a building was linked to the use of fewer pain-reducing medications by patients recovering from surgery.  The experiment reported here was designed to further examine the role of plants in pain perception.  We found that more subjects were willing to keep a hand submerged in ice water for 5 min if they were in a room with plants present than if they were in a room without plants.  This was found to be true even when the room without plants had other colorful objects that might help the subject focus on something other than the discomfort.  Results from a room assessment survey confirmed that the room with colorful, non-plant objects was as interesting and colorful as the room with plants present, but the presence of plants was perceived as making the air in the room fresher.

Stress Recovery During Exposure to Natural and Urban Environments
SUMMARY:Different conceptual perspectives converge to predict that if individuals are stressed, an encounter with most unthreatening natural environments will have a stress reducing or restorative influence, whereas many urban environments will hamper recuperation.   To investigate these hypotheses, 120 subjects first viewed a stressful movie, and then were exposed to color/sound videotapes of one of six different natural and urban settings.  Data concerning stress recovery during the environmental presentations were obtained from self-ratings of affective states and a battery of physiological measures: heart period, muscle tension, skin conductance and pulse transit time, a non-invasive measure that correlates with systolic blood pressure. Findings from the physiological and verbal measures converged to indicate that recovery was faster and more complete when subjects were exposed to natural rather than urban environments. Findings were consistent with the predictions of the psycho-evolutionary theory that restorative influences of nature involve a shift towards a more positively-toned emotional state, positive changes in physiological activity levels, and that these changes are accompanied by sustained attention/intake. Content differences in terms of natural vs human-made properties appeared decisive in accounting for the differences in recuperation and perceptual intake.


If you would like to learn more about Experimental Methodology, here are some books:

Experimental and Quasi-Experimental Designs for Research by: Donald T. Campbell and Julian Stanley

Experimental and Quasi-Experimental Designs for Generalized Causal Inference By: William R. Shadish, Thomas D. Cook, and Donald T. Campbell

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