Effects of invisible body and optic flow on experience of users voluntarily walking in a VR environment

Studies have demonstrated that a multi-modal virtual reality (VR) system can enhance the realism of virtual walking. However, a few studies explore the body awareness altered by visual presentation of virtual body and optic flow during locomotion in VR. This study investigated the impact of invisible body and optic flow on experience of users voluntarily walking in a camera-image VR environment. Participants wearing a head-mounted display performed six-step walking at their own timing. Three experimental conditions providing visible body and optic flow as a baseline, invisible body and optic flow, and invisible body and no flow, were conducted on three different days. We found that losing visual body per se decreased the feeling of being-there-now. However, providing continuous optic flow maintained virtual presence equivalent to the baseline in terms of immersion and natural walking, as opposed to providing discontinuous flow. We discussed these results in association with body awareness.