Influence of user posture and virtual exercise on impression of locomotion during VR observation

International audienceA seated user watching his avatar walking in Virtual Reality (VR) and imagining being walking may have an impression of walking. In this paper, we show that such impression can be extended to other postures and other locomotion exercises. We present two user studies in which participants worn a VR headset and observed a first-person avatar realizing virtual exercises. In the first experiment, the avatar walked and participants (n=36) tested the simulation in 3 different postures (standing, sitting and Fowler's posture). In the second experiment, other participants (n=18) were sitting and observed the avatar walking, jogging or stepping over virtual obstacles. We evaluated the impression of locomotion by measuring the impression of walking (respectively jogging or stepping) and embodiment in both experiments. The results show that participants had the impression of locomotion in either sitting, standing and Fowler's posture. The Fowler's posture however significantly decreased both the level of embodiment and the impression of locomotion. Moreover the sitting posture seems to decrease the sense of agency compare to standing posture. Results also show that the majority of the participants elicited an impression of locomotion during walking, jogging and stepping virtual exercises. The embodiment was not influenced by the type of virtual exercise. Overall, our results suggest that an impression of locomotion can be elicited in different users' postures and during different virtual locomotion exercises. They provide valuable insight for numerous VR applications in which the user observes a self-avatar moving, such as gait rehabilitation, training, video games, etc