Quantitative Measurement of Tool Embodiment for Virtual Reality Input Alternatives

Virtual reality (VR) strives to replicate the sensation of the physical environment by mimicking people's perceptions and experience of being elsewhere. These experiences are of-ten mediated by the objects and tools we interact with in the virtual world (e.g., a controller). Evidence from psychology posits that when using the tool proficiently, it becomes em-bodied (i.e., an extension of one's body). There is little work,however, on how to measure this phenomenon in VR, andon how different types of tools and controllers can affect the experience of interaction. In this work, we leverage cognitive psychology and philosophy literature to construct the Locus-of-Attention Index (LAI), a measure of tool embodiment. We designed and conducted a study that measures readiness-to-hand and unreadiness-to-hand for three VR interaction techniques: hands, a physical tool, and a VR controller. The study shows that LAI can measure differences in embodiment with working and broken tools and that using the hand directly results in more embodiment than using controllers.