Exploring the effect of avatar and tool appearance on ownership and agency during virtual tasks

The feeling of ownership of, for instance, an avatar in virtual reality (VR), can be induced through multisensory correspondences during active body movements. These movements provide a sense of agency which extends to tool use. This thesis explores how familiarity with a tool’s appearance affects behaviour and subjective ratings of ownership, agency, and familiarity. The first two experiments investigated how familiarity with the visual characteristics of a tool affect behaviour and agency. Participants performed a target-pointing task with different computer cursors and rated the sense of agency and naturalness. Ratings were highest with the familiar cursor orientation, which also supported the quickest, most direct movements. We then varied tool size in VR. Participants completed a pointing task where the size of a virtual hand varied and rated their feelings of ownership and agency. No effects of hand size were found on pointing behaviour or agency, but ownership was higher for the size-matched hand. To assess the effect of delays on target tracking in VR, participants tracked a moving sphere with a virtual ball, experiencing delays of up to 900 milliseconds between their real movements and the virtual ball movements. Increasing delay led to spatial tracking error and tracking lag. Ownership and agency ratings decreased with increased delay and negatively correlated with tracking error and lag. Baseline Galvanic Skin Responses were significantly affected by task difficulty for large delays. These experiments show that the appearance of virtual tools significantly affects pointing behaviour and the feeling of agency on a computer screen. This did not translate to less familiar VR settings, suggesting familiarity with a tool’s appearance could drive these results. When a tool does not behave as expected, it further breaks the feeling of agency. Subjective ratings might be linked to perceived task performance, a possible focus for future work.