# Development and Validation of a Tool for VBOI (Virtual Body Ownership Illusion) Level Assessment
###### Abstract  
Virtual Body Ownership Illusion (Virtual BoI) refers to the perceptual, cognitive, and behavioral changes that occur due to the illusion that a virtual body is one's own actual body. Recent research has focused on inducing Virtual Body Ownership Illusion (Virtual BoI) using various physical conditions of VR environments such as haptic feedback and 360-degree immersion, among others. The level of Virtual BoI has been recognized as an important factor in VR-based clinical therapy programs where patient immersion is crucial. However, a common issue is the lack of standardized evaluation tools for Virtual BoI, with most experiments relying on ad hoc tools based on experimental conditions or lacking consideration for the physical design elements of VR. This measurement tool was designed to consider the characteristics of recent VR devices, such as haptics and hand tracking, in the design of experiments and questionnaires. The tool is composed of sub-attributes related to VR technology, including Embodiment, Presence, Visuo-tactile, Visuo-proprioceptive, and Visuo-Motor. Based on a review of the existing literature, we hypothesized that the Virtual BoI scores would vary depending on manipulation methods, viewpoints, and haptic conditions. An experiment was conducted with 39 participants, who performed the same task under four different conditions using a virtual hand. Virtual BoI scores were assessed using the evaluation tool developed for this study. The questionnaire underwent CFA, and three items with factor loadings below 0.5 were removed, resulting in a total of 14 items. Each subscale demonstrated high reliability, with Cronbach's alpha values greater than 0.60. When developing experiments, clinical programs, or VR content related to Virtual BoI, the evaluation tool presented in this study can be used to assess the level of Virtual BoI. Additionally, by considering technological elements such as haptics and hand tracking, VR environments can be designed to enhance the level of Virtual BoI. H +
Footnote †: journal:  
0000-0001-188432  
One of the prominent experiments related to BOI is the Rubber Hand Illusion (RHI) paradigm. This experiment involves simultaneously touching a participant's real hand and a rubber hand using a small brush, demonstrating that it can induce an illusion as if the experience were actually occurring from the rubber hand [5]. However, the Rubber Hand Illusion (RHI) paradigm imposes physical constraints due to the presence of a rubber hand, limiting its applicability for expanded research. However, BOI using virtual reality technology has been adopted in research because it allows for the creation of scenarios with various conditions and modifications (such as different situations or physical constraints) [4]. There have been various studies in different conditions and fields aiming to develop therapeutic programs using Virtual BOI. [PERSON] et al. conducted a study on 15 obese patients and 15 normal-weight participants to investigate changes in the ownership perception of a virtual body with an abdominal region and the perception of the actual body [6]. [PERSON] et al. investigated depression treatment in VR by inducing Virtual BOI among depressed patients. They conducted an 8 min scenario in a VR environment and subsequently demonstrated improvements in depression severity, self-criticism, and self-compassation, highlighting the potential for depression therapy in VR [7]. [PERSON] and [PERSON] induced a Full Body Illusion in chronic pain patients, where it seemed as though their nerves were separated from their own bodies [8]. They confirmed a reduction in pain intensity. [PERSON] et al. conducted an experiment with post-stroke upper limb paralysis patients using mirrors to present virtual movements, aiming to propose the potential of a VR-based therapy program for chronic stroke patients [9]. [PERSON] et al. researched the potential for reducing pain in patients through the observation of virtual bodies [10].