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

reviewed and approved by the Department of Landscape Architecture Ethics Committee (Approval Ref. 039698). Experimental procedure Online participants were asked for demographic information and their affective states (emo- tions) before and after 2 interventions–the first being a stress induction (a loud noise) and the second a video designed to provide a degree of relaxation and calm (Fig 2). Participants were randomly assigned to one of the 4 videos representing the 4 different conditions outlined above. In stage 1, the participants provided their demographics and their baseline affective states; the affective questionnaire’s items (see Measures, below) were always presented in random order. Stage 2 began immediately after completing the affective questionnaire. Upon loading the next survey section, the sound of a fire alarm (a stressor) was played for 15 seconds. As required by the ethics review, participants were pre-warned that they would be listening to an intrusive, annoying noise. Participants were then asked again to rate their affective states after experiencing the stressor. In Stage 3, participants were randomly assigned one of the four vid- eos to watch. In-video instructions reminded them to activate the full-screen and how to move the camera around. A timer-controlled button prevented the participants from skipping ahead, allowing them to proceed only after 330 seconds had passed. After the video, the partici- pants rated their affective states one last time and were asked for their perceptions and comments. Measures

The affective states were measured via the International Short Form of the Positive and Nega- tive Affect Schedule (I-PANAS-SF, Thompson, 2007). This questionnaire has ten items, five measuring Positive Affect states and five Negative Affect states; the items are rated on a 5-point Likert scale, indicating how much the participant is feeling an emotion from “not at all” to “extremely”. The two main dependent variables, the Negative Affect (NA) and the Posi- tive Affect (PA), were computed by summing the scores from the I-PANAS-SF scales, Table 2. Experimental conditions. Condition No. of species added No. of individual plants added Sounds 1—Control 0 0 Gentle breeze 2—Low plant diversity 4 plants 60 Gentle breeze 3—High plant diversity 21 plants 60 Gentle breeze 4—High plant diversity and a diverse natural soundtrack 21 plants, 8 Bird songs 60 Birdsong and water https://doi.org/10.1371/journal.pone.0297179.t002 Fig 2. Experimental procedure with affective states being measured at three discrete points, i.e. before a stressor, after a stressor and after a video of green space. https://doi.org/10.1371/journal.pone.0297179.g002 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 6 / 20