Outdoor Natural Versus Built Experiments: A Scoping Review and Methodological Recommendations for Psychological Science

The beneficial effects of exposure to nature on health and well-being, including enhanced relaxation and improved mood and attention, are well-established. Less evidence exists on understudied outcomes related to clinical populations (e.g., substance use outcomes, decision-making), mainly from laboratory experiments warranting outdoor studies. The purpose of this scoping review was to review and summarize the rich experimental literature of nature exposure on psychological outcomes, and form updated methodological recommendations for future outdoor basic experiments isolating the effect of nature exposure. Four databases and ten systematic reviews were searched. From 6394 references, 60 articles (reporting experiments or secondary analyses) comparing natural versus control-built environments, utilizing short exposure in the environment, and examining psychological outcomes were included and synthesized. We discuss limitations and innovative approaches and provide methodological recommendations. Future research should recruit large and gender-balanced samples, expand to clinical populations, include baseline measurements, assess individual differences, and investigate behavioral and other outcomes that are sparse in the literature. Researchers might consider expanding the dichotomous green–gray environments, pay attention to the sense of safety and participant masking, and assess and report environmental conditions. These recommendations may facilitate investigating unique outcomes that are missing in the literature, which hold implications for nature-prescription and intervention programs.