Virtual reality transition to underground: human responses across sequential spatial transitions.

Given the growing demand for the active utilization of underground spaces, understanding their effects on humans is crucial. However, constructing physical underground spaces for research is often costly and inflexible. In response, virtual reality (VR) provides a flexible and cost-effective alternative for simulating such environments and evaluating human responses. Yet, accurately replicating the experience of being underground in VR remains challenging. This study proposes a novel framework-Virtual Reality Transition to Underground (VRTU)-designed to stimulate the experience of descending from aboveground to underground environments. VRTU incorporates a sequential transition process through aboveground, transporting, and underground spaces, each enhanced with multimodal sensory cues to promote immersion. To validate this framework, we conducted an experiment within the VRTU environment, assessing participants' responses using the Positive and Negative Affect Schedule (PANAS), Igroup Presence Questionnaire (IPQ), a cognitive task, a subjective perception questionnaire, and heart rate measurement. Results revealed a significant increase in negative affect state following exposure to the VR-based underground space, along with physiological changes consistent with real-world underground settings. These findings demonstrate that the VRTU framework effectively captures core aspects of the underground space experience and offers a viable tool for evaluating human responses in immersive simulations prior to physical implementation.