Effects of visual exposure to wood on human affective states, physiological arousal and cognitive performance: A systematic review of randomized trials

Background Bringing features of nature indoors can positively influence indicators of human stress. Since wood is a natural material, it may produce similar benefits. The objective of the review was to (1) examine the influence of visual (real or virtual) contact with either real or imitated indoor wooden surfaces on certain stress indicators, that is affective, physiological or cognitive performance outcomes (compared to non-wooden surfaces) and to (2) assess the methodological quality of the reviewed studies. Method We conducted a systematic literature search for English articles on Scopus, PubMed, Web of Science, Cochrane Central and Google Scholar on 6 August 2019. The results of the eligible studies were synthesized narratively in light of the identified methodological shortcomings. Results We reviewed nine studies with 386 participants in total. Studies with longer exposure times to wood generally observed improved affective states and decreased physiological arousal in wooden settings, but the results are not entirely clear-cut. We discuss several methodological issues uncovered in the reviewed studies and provide guidelines for future robust research. Conclusions Current evidence suggests that visual wood exposure may improve certain indicators of human stress, but additional research is needed to confirm the existing findings.