2nd Edition of Public Health World Conference (PHWC) 2026

Abstract

Recent rapid urbanization and population concentration are associated with higher levels of stress and depressive symptoms through reduced social privacy and related environmental pressures. Against this background, urban parks play an important role in supporting stress reduction and emotional restoration for visitors. In particular, planting layer structure is one of the major components of parks, playing an important role in landscape formation and user experience, and it has been suggested that various combinations of vegetation layers within parks may enhance users’ psychological restoration.

However, studies objectively examining the effects of planting layer structure on stress reduction through physiological indicators remain insufficient. Meanwhile, studies employing virtual reality (VR) environments and electroencephalography (EEG) measurements as substitutes for real environments have recently increased. Accordingly, this study presented images with different planting layer structures in a VR environment and measured EEG responses. Through this approach, the study aimed to quantitatively analyze the relationship between planting structure and stress reduction effects and to provide basic data for future urban park and green space planning.

The study sites were selected from 29 children’s parks in Gangneung-si, and three parks with high use intensity were chosen using QGIS 3.28 and SPSS 29. A field vegetation survey was then conducted in each park, and based on the results, planting layer types for VR visual stimuli were derived. The selected planting layer structures consisted of seven types: canopy, shrub, canopy + shrub (coniferous and broad-leaved), sub-canopy + shrub (coniferous and broad-leaved), and canopy + sub-canopy + shrub. Photographs were taken for each layer type in the selected parks, and visual disturbances were corrected using Adobe Photoshop 25. Three images were prepared for each planting type and presented as visual stimuli to 20 university students using a VR headset (Meta Quest 3). Before measurement, a stress condition was induced through 5 minutes of major-related question solving, followed by 1 minute of pre-EEG measurement. The same procedure was also conducted in the VR environment. In the main experiment, each image was presented for 15 seconds, with a 5-second gray screen inserted between stimuli to minimize interference. EEG was measured using 16 channels, and analysis and EEG mapping were performed using Laxtha Telescan software. For detailed comparison among planting layer structures, the EEG data were reclassified into single-layer (canopy and shrub), double-layer (canopy + shrub and sub-canopy + shrub, each with coniferous and broad-leaved variants), and multi-layer (canopy + sub-canopy + shrub) categories.

The pre-measurement data before and after VR headset use made it difficult to interpret the differences across VR environments as a consistent trend. When EEG indices were compared across planting layer structures, alpha waves increased from single-layer to double-layer and multi-layer structures, whereas beta and high-beta waves decreased. In addition, the indices reflecting relaxation relative to tension RAB (Ratio of Alpha to Beta), RAHB (Ratio of Alpha to High Beta), and RST (Ratio of SMR to Theta) were highest in the multi-layer structure, followed by the double-layer and single-layer structures. In the comparison between double-layer structures distinguished by broad-leaved and coniferous tree types, the broad-leaved type showed higher alpha, RAB, RAHB, and RST values and lower beta values than the coniferous type. EEG mapping also indicated relatively higher alpha activation in the occipital and parietal regions. Overall, the integrated analysis of the measured indices showed that stress reduction tended to improve from single-layer to multi-layer structures. In addition, relatively stable EEG responses were observed in broad-leaved planting spaces compared with coniferous ones. These findings suggest that the results may serve as basic data for planting design strategies in urban parks aimed at enhancing stress reduction effects.