Application of heart rate variability and eye-tracking in the study of emotional responses to traditional open spaces: a comparative analysis of the Forbidden City and St. Peter’s Square

Empirical research on the relationship between architectural spatial form and user experience has grown rapidly; however, traditional monumental open spaces remain insufficiently examined compared to urban and indoor environments. This study addresses this gap by providing a comparative, data-driven investigation of two contrasting heritage spatial typologies – the Forbidden City in Beijing and St. Peter’s Square in Vatican City. An immersive virtual reality (VR) experiment was conducted with 50 participants, integrating heart rate variability (HRV), eye-tracking metrics, and subjective evaluations to capture both physiological and perceptual responses. The results reveal distinct psychophysiological patterns associated with different spatial configurations. The axial, sequential, and enclosed spatial structure of the Forbidden City is associated with more stable autonomic responses and sustained visual attention, whereas the open and centripetal layout of St. Peter’s Square is linked to broader visual exploration and greater emotional variability. By integrating multimodal physiological measures with controlled VR environments, this study extends existing research beyond conventional settings and demonstrates a novel empirical framework for analyzing traditional architectural spaces. The findings highlight the role of spatial morphology in shaping cognitive and emotional experience, offering transferable insights for user-centered design in cultural and public spaces.