Illusory perception of one's own movements in virtual reality

Abstract

Introduction Perception of one's own movements (i.e., kinaesthesia) is achieved by integrating multiple sensory inputs such as proprioceptive and visual signals. Firstly, we investigated whether visual cues coming from an embodied first-person avatar can be used for the purpose of kinaesthesia. Secondly, as humans can identify living organisms and understand their actions solely based on a small animated set of well-positioned points of lights (i.e., by recognizing biological motion), we hypothesize that such visual motion cues can also participate in kinaesthesia. Materials and methods We used the “virtual mirror paradigm” in which the participant's left forearm was passively moved, and these movements controlled the displacements of both forearms of a first-person avatar. In a first experiment, right (ipsilateral) visual information was combined with left (contralateral) proprioceptive information to induce kinaesthetic illusions in the participant's static right forearm. The second experiment used the same paradigm, but the virtual forearms were either realistic or represented by three points of light. Thirty-four female participants and 30 others took part in the first and second experiment, respectively. Results Combination of visual information from the avatar with proprioceptive information from the participant's moving forearm elicited kinaesthetic “mirror like illusions”. Such illusions were evoked both with realistic virtual forearms and with point-light forearms. Discussion Visual information coming from an embodied first-person avatar can efficiently participate in kinaesthesia. In addition, kinaesthesia does not require visual access to an elaborate representation of the body segment, access to its biological movement may be sufficient.