Effects of virtual hands and feet on the onset time and duration of illusory body ownership

In the illusory body ownership, humans feel as if a rubber hand or an avatar in a virtual environment is their own body through visual-tactile synchronization or visual-motor synchronization. Despite the onset time and duration of illusory body ownership has been investigated, it is not clear how the onset time and duration change when a part of the body is missing from the full-body. In this study, we investigated the completeness of the full-body for the illusion onset and duration by comparing the following conditions: complete avatar, avatar missing hands and feet, and avatar with hands and feet only. Our results suggest that avatar hands and feet only shorten the duration of the illusion, and missing body parts, such as only hands and feet or no hands and feet, reduce the sense of body ownership and of agency. However, the effects of avatar completeness on the onset time are unclear, and no conclusions can be made in either direction based on the current findings.