Background: Previous research suggests an evolutionary predisposition for humans to seek out and maintain a connection with nature. Natural elements including sunlight, plants, water, and natural scenery have been shown to be beneficial to human health and functioning.

Objective: This dissertation aimed to replicate previous research on the benefits of exposure to nature stimuli and extend this knowledge by testing for an effect of nature on self-control.

Methods: Two randomized-controlled trials tested the effects of exposure to varying degrees of nature stimuli. In Study One, college students (N = 203) were randomly assigned to either undergo an ego-depleting task or a control task and to view either photographs of natural scenes or urban architecture. Outcomes were changes in mood, task persistence, and health decision making. In Study Two, college students (N = 126) were randomly assigned to either complete tasks in a room with natural elements (sunlight, plants, water fountain, window views of scenery) or a room devoid of any natural stimuli (a windowless storage room). Outcomes were changes in mood, physiology, task performance and persistence, and health decision making.

Results: In Study One, participants completing the ego-depletion task reported feeling more frustrated, confused, and fatigued compared to participants completing the control task, but this effect quickly dissipated. A trend emerged for ego-depleted participants viewing nature photographs, such that they reported greater overall feelings of vigor compared to nature photo viewers completing the control task. There were no differences between groups in task persistence or health decision making. In Study Two, participants in the nature room showed a greater decrease in heart rate throughout the session compared to participants in the control room. Additionally, participants in the control room successfully solved more anagrams than participants in the nature room. No other effects for mood, task persistence, physiology, or health decision making were significant.

Conclusions: With the exception of greater relaxation of heart rate, no evidence was found that nature exposure through viewing scenic photographs or working in a space with natural stimuli has any meaningful effects on mood, self-control, or health decision making over a short time period. Additional research is needed to elucidate the type and duration of nature exposure necessary to produce beneficial effects, and for whom exposure may be most beneficial.

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