Does increasing biodiversity in an urban woodland setting promote positive emotional responses in humans? A stress recovery experiment using 360-degree videos of an urban woodland

To ensure statistical validity, the required sample size was estimated a priori using power analysis on G*Power (version 3.1.9.7; [65]). The estimated sample size was N = 324, consider- ing the analysis design (repeated measures), a significance level of α = 0.05 and 80% power and expecting small effect sizes (Cohen’s d = 0.15; [66]). This expectation was informed by previ- ous meta-analyses, which reported moderate to small effect sizes on the affective states [52] and smaller effects when the nature exposure was mediated by video [51] compared to a real nature location. Results Descriptive data There were 602 responses to the survey, 414 of which were complete (68% completion rate). After excluding those responses that did not meet the required criteria (see above), 372 responses were analysed. Females comprised 63% of respondents and the age distribution was skewed towards groups aged 18–24 (43%) and 25–34 (34%). The ethnicity was predominantly White (66%) fol- lowed by Asian (19%) and Mixed (8.3%). Black and other ethnic groups collectively repre- sented 6% of the sample. Two-thirds of the participants (69.7%) declared to have watched a 360-degree video before. Most of the participants took the survey on a laptop (64.4%) or a desktop (23.4%), as recommended, while fewer used a phone (10.8%) or a tablet (1.3%). In terms of engagement with nature and outdoor space, 47.8% of the participants recalled having spent ‘a lot of time outdoors’ in their childhood while 41.7% recalled having spent ‘a moderate amount of time’ outdoors.

The mean value for the Inclusion of Nature in Self was 4.05 (SD = 1.64), however, most of the responses fell on scores of ‘5’ (27%) or ‘2’ (19%), suggesting some polarisation around those who considered nature as an important part of their lives, and those who felt more removed from nature. Across all treatments, the perceived value of the environment for plants and wildlife (here- after referred to as “perceived biodiversity”) was rated “good” by 53% of participants, followed by “very good” (23.4%), “neither good nor bad” (18.5%) and “bad” or “very bad” (5% collec- tively). To ensure statistical balance, the three lower categories were grouped together in subse- quent analysis (“i.e. bad or neutral). On average, the completion time of the procedure was 13 minutes. Affective responses to the biodiversity in the videos All video conditions reduced Negative Affect (NA). Negative affect scores varied significantly with time (i.e. stages; p < 0.005; Table 3), but not due to condition (p = 0.31). For all condi- tions, NA scores increased significantly after the stressor but decreased significantly after watching (any of) the videos (Fig 3, left). Increasing the amount of biodiversity or natural sounds in the videos had no significant effect on reducing negative scores. Pooling data across the conditions showed that Positive affect (PA) scores changed with time (p = 0.02). Post hoc tests showed that PA scores were statistically lower after the stressor (p = 0.014) but not after the relaxing video (p = 0.14), compared to the baseline (Fig 3, right).

There was no significant difference in the PA scores before and after the condition videos. There were no significant differences between any of the experimental groups at any stage (p = 0.91), i.e. the amount of additional biodiversity or natural sounds were not affecting the Positive Affect scores, compared to a control. PLOS ONE Does increasing biodiversity in an urban woodland setting, promote positive emotional responses in humans? PLOS ONE | https://doi.org/10.1371/journal.pone.0297179 February 7, 2024 8 / 20