Does Time Slow Down When Green Becomes Visible? A Causal Analysis of Visual Green Exposure and Urban Park Engagement

Urban green spaces are vital resources for enhancing residents’ health and well-being. But is it truly the “visible green” that encourages people to use parks, or are other factors at play? This critical question has long lacked empirical evidence at the causal level. Using Tokyo’s 23 wards as a case study, this research integrates mobile phone signaling data with panoramic park images and applies quasi-experimental methods to uncover the causal effects of Visual Green Exposure (VGE) on park dwell time and walking distance. The study further finds that these effects are significantly moderated by spatial density and temporal rhythms.

Figure 1: Study area and the distribution of 20 urban parks in Tokyo’s 23 wards (including street-view images of three representative parks)

Urban parks not only provide ecological and recreational functions, but also serve as key venues for promoting physical activity and social interaction. Previous studies suggest that visual green exposure (VGE) within parks may influence visitors’ experiences and behavioral patterns. However, most existing evidence relies on cross-sectional correlational analyses, which struggle to rule out confounding factors such as park facilities, maintenance quality, and surrounding neighborhood characteristics. This “green advantage bias” prevents policymakers from clearly determining whether enhancing visual greenery alone can independently increase park use. This study aims to fill this gap in causal inference.

Figure 2: Research framework (data preprocessing, spatial integration, and causal analysis workflow)

The research team integrated annual mobile location data (covering 72,870 park visit records) with 13,791 panoramic street-view images. Semantic segmentation techniques were used to quantify the proportion of green pixels in each panorama, with a 30% threshold used to distinguish high- and low-VGE groups. To enable causal inference, the study employed three quasi-experimental methods—propensity score matching (PSM), inverse probability weighting (IPW), and overlap weighting (OW)—to estimate the average treatment effects (ATE) of high VGE on dwell time and walking distance, while controlling for visitor characteristics, park attributes, and spatiotemporal variables.

Figure 3: Results of propensity score matching: (a) distribution of propensity scores before and after matching; (b) standardized mean differences of covariates

Figure 4: Estimated causal effects of visual green exposure on park dwell time and walking distance

The key findings of the study include:

Overall causal effects: Park visits with VGE above 30%, compared with low-VGE visits, show an average increase of 3.36 minutes in dwell time (a 9.6% increase) and 116.95 meters in walking distance (a 16.2% increase). The direction of effects is consistent across all three methods, confirming the robustness of the results.

Spatial heterogeneity: The effects of VGE are more pronounced in parks located in urban core areas. High VGE increases dwell time by 6.6 minutes and walking distance by 90 meters. In suburban parks, although dwell time also increases (by 7.9 minutes), walking distance decreases by 84 meters. This suggests that in high-density urban areas, visual greenery functions as an “urban oasis” with higher marginal value.

Temporal heterogeneity: The VGE effect on weekends is more than ten times that on weekdays (an increase of 16.7 minutes in dwell time versus 1.6 minutes). The strongest effects occur from morning to midday, while effects turn negative in the evening. Seasonally, the VGE effect is most pronounced in spring and autumn (cherry blossom and autumn foliage seasons), and not significant in winter.

These findings provide evidence-based guidance for urban park planning:
(1) In high-density urban areas, priority should be given to multi-layered vegetation configurations (trees + shrubs + ground cover) to maximize visual greenery within limited space;
(2) Park maintenance schedules should align with peak usage periods (weekends and morning-to-midday hours) to ensure optimal landscape presentation;
(3) Suburban parks can adopt zoning strategies—concentrating greenery in quiet resting areas while maintaining openness in active zones;
(4) Evergreen species and winter-flowering plants should be introduced to extend visual attractiveness throughout the year.
Together, these strategies can effectively enhance the social benefits of parks and their public health value.

This study is part of the Urban Park Green Space subproject within the Urban Blue–Green Infrastructure research agenda of the Shanghai Key Laboratory of Urban Design and Urban Science (LOUD). The research article, “Seeing green, staying longer? A causal analysis of visual green exposure and urban park engagement using mobility and panoramas data,” was published in the flagship urban planning journal Landscape and Urban Planning.

This research was supported by the Shanghai Nature and Health Foundation, the Winston Foundation, the Pudong Pearl Program (Leading Talent Project), the Shanghai Universities Distinguished Professor Program (Oriental Scholar), the Overseas High-Level Young Talent Introduction Program, and the Shanghai Municipal Education Commission (Key Project on AI-Driven Research Paradigm Reform and Disciplinary Empowerment), among others.

Reference
Zhou, Y., Ren, X., Yabe, T., & Guan, C. (2026). Seeing green, staying longer? A causal analysis of visual green exposure and urban park engagement using mobility and panoramas data. Landscape and Urban Planning. https://doi.org/10.1016/j.landurbplan.2026.105579