# Effect of a Virtual Biophilic Residential Environment on the Perception and Responses of Seniors
## 1 Introduction  
### Background and Purpose  
Rapid urbanization has indigenized residential environments and lifestyles that are separated from nature. Modern people must travel farther to experience quality nature, which requires significant financial and time resources and physical efforts. [PERSON] [1] explains the relationship between humans who constantly visit nature and the nature inherent in us through the biophilia hypothesis. Biophilia refers to humans' instinct to value life. According to the biophilia hypothesis, activating internal biophilia can improve human physiological functioning [2]. Based on this, biophilic design has been promoted in modern built environments to induce positive experiences with nature and activate biophilia. Biophilic design aims to evoke positive interactions with nature within architectural contexts, thereby facilitating improvements in human physiological functions [3]. [PERSON], [PERSON], and [PERSON] [3] identified the benefits of nature relevant to positive human responses to embody the concept of biophilic design. Benefits of nature include improved immune function [4] and enhanced physiological and psychological recovery [5, 6], as well as positive impacts on physical health and well-being [7]. Conversely, environmentsthat lack the sense of nature create advantageous conditions for disease spread and socio-psychological deficits [8], particularly affecting vulnerable populations like seniors, who are more susceptible to environmental stress [9]. As seniors age, they prefer to spend more time at home and recover in familiar places [10]. Interaction with nature in the residential environment helps activate seniors' multisensory experiences and cognitive functions [11], contributing to their overall quality of life (QoL) [12; 13]. Nevertheless, urban areas with high housing density, such as apartment complexes, limit seniors' opportunities to experience nature. Additionally, related studies on the seniors' experience with nature focused on medical and welfare facilities, resulting in a lack of research addressing everyday places, such as residential spaces. Previous studies have utilized field investigations, questionnaires, and post-occupancy evaluations to identify natural elements contributing to seniors' health [14; 15; 16; 17]. Recently, related research has employed virtual environments (VEs) as experimental platforms to assess the quantitative effects of biophilic design. These studies indicate that natural experiences in VEs provide benefits comparable to those in real-world settings [18; 19; 20]. The authors have established VEs as reliable experimental tools, suggesting the potential for integrating digital methodologies into biophilic practices. However, many research challenges and opportunities remain for biophilic VEs. First, most studies focus on the independent effects of biophilic elements, limiting our understanding of their combined effects. Second, there is a need for more discussion on the impact of biophilic design across different scales. Third, VE simulations have primarily focused on the physical planning of biophilic design. Whether the digital planning of biophilic design can also evoke positive responses is unsolved. Lastly, most VE study participants are healthy young adults, resulting in insufficient data on seniors' physiological responses and perceptions. This study focuses on the necessity of and potential for expanding biophilic design for seniors within urban apartment houses. This study aims to apply physical and digital biophilic elements according to residential scales using VEs and analyze the seniors' physiological and subjective responses. The research addresses three questions: (1) Does exposure to complexly designed virtual biophilic residential environments elicit positive physiological responses in seniors? (2) Do digital design interventions in virtual biophilic residential environments produce positive physiological responses among seniors?