Evaluating the impact of spatial openness on stress recovery: A virtual reality experiment study with psychological and physiological measurements

Proximity to nature aids in stress recovery, but the impact of indoor spatial openness on this process is under-researched. An architectural model with three types of interior openness—closed, semi-open, and open—was designed, and a within-group experiment with 52 participants was conducted. Our data-centric approach utilized psychological measurements (State-Trait Anxiety Inventory test (STAI), post-experiment questionnaires) and physiological measurements (electroencephalogram (EEG), eye-tracking, skin conductance level (SCL)) in a Cave Automated Virtual Environment. A linear mixed-effect model assessed the dose-response relationship between openness conditions and ergonomic stress recovery outcomes. Larger open spaces significantly reduced stress, increased α/β and θ/β ratios, decreased pupil diameters, and lowered SCL. Significant correlations were found between STAI scores and frontal θ/β ratios (r = 0.25), post-experiment evaluations and pupil diameter (r = 0.20). These findings suggest that open environments may reduce stress through brain and visual stimulation. Additionally, α/β and θ/β ratios in the occipital and left frontal lobes, along with eye movement metrics, were sensitive to environmental changes. The integrated stress recovery value moderately correlated with visual fixation area coverage (r = 0.52) and spatial openness evaluations (r = 0.50). Our results support the conclusion that architects and designers can promote stress recovery by creating spacious layouts in coordination with other stress-reducing features.