The Role of Methodological Choices in the Effects of Experimental Exposure to Simulated Natural Landscapes on Human Health and Cognitive Performance: A Systematic Review

We review the methods and findings of experiments that have examined the effects of exposure to simulated natural landscapes on human health and cognitive performance. Keyword searches of PubMed, Scopus, and Web of Science resulted in the inclusion of 175 experiments in 148 research articles. that were published/in press by December 31, 2018. We report how often landscape features and human factors are controlled for within these experiments, thereby—for the first time—recording specifically what elements of “nature” and the built/social environment are used when testing the benefits of green space and blue space exposure. We also document all the simulation methods that are used (e.g., duration, number of exposures, senses engaged, and devices used). Next, to determine what methodological decisions influence study findings, we compare positive versus mixed/null or negative findings across 14 potential moderators. Only study quality and outcome measure influence findings; experiments without control groups or randomized treatments reported more positive findings than expected. Experiments studying perceived restoration also reported more positive findings than expected—remarkably, 95% of such experiments reported simulated nature was indeed restorative. We discuss the possibility that these findings may indicate publication bias in favor of overreporting the salutory impacts of natural landscapes. We conclude our review with a synthesis of best practices for future research studies.