Rapid urbanization and spatial constraints in high-density residential areas pose significant challenges to public health and well-being. This study investigates the mechanisms by which the visual environment of urban micro public spaces shapes residents’ psychophysiological responses to encourage spontaneous physical activity and advance active health. Using machine learning and semantic segmentation, 9 core visual elements across 20 micro public space scenes in high-density urban neighborhoods were quantified. An immersive virtual reality (VR) experiment was conducted, collecting synchronized multimodal psychophysiological data from 60 participants, which yielded 600 valid observations. Through an analytical framework combining Self-Organizing Map (SOM) clustering and Random Forest (RF) modeling, three distinct functional archetypes were identified: Restoration-Supporting, Activity-Promoting, and Stress-Inducing. The Activity-Promoting archetype was most effective in fostering spontaneous activity intention, characterized by a high proportion of activity areas, a moderate sky view factor, and minimal physical barriers. RF modeling further pinpointed pedestrian density, activity area ratio, and green space ratio as key visual drivers of health-promoting outcomes. Based on these findings, a “Visual Activation for Active Health” framework is proposed. It posits that moderate visual-environmental stimulation is the core mechanism for transforming passive spaces into health-promotive settings, thereby establishing a theoretical foundation for the evidence-based design of healthy and sustainable urban environments.

Micro-housing has gained prominence as a sustainable urban residential solution, yet the impact of its spatial design on occupants’ perceptual and physiological responses remains underexplored. This study employs a multimodal approach to investigate how three key spatial elements—spatial scale (SS), window-to-wall ratio (WWR), and interface material (IM)—influence human perception in micro-housing environments. A full-factorial experimental design with 12 distinct conditions was implemented in a controlled laboratory setting. We collected both subjective evaluations and multimodal physiological data—including electroencephalography (EEG), electromyography (EMG), skin conductance (SC), and blood volume pulse (BVP)—from 30 participants. Subjective results indicate that all three spatial elements significantly affect spatial perception and overall comfort, with the influence hierarchy being SS > WWR > IM. Notably, a compensatory effect was observed: increasing the WWR enhanced the perceived spatial area, particularly in mid-sized spaces. Physiologically, SS significantly influenced SC, WWR affected the EEG beta power ratio (BR), and IM impacted the EEG alpha/beta (A/B) ratio, corroborating the subjective findings. Interaction effects were also identified: SS interacted with WWR in area evaluation, and with IM in both area and window size evaluations. This study provides empirical evidence that spatial form elements directly and interactively shape human perception, offering practical insights for enhancing livability in micro-housing through design optimization. The integration of subjective and physiological metrics also establishes a robust methodological framework for future research on human-centered spatial design.