Abstract
Virtual reality (VR) became an influential tool in vision science. One challenge is to create virtual environments that are experienced as realistic. This depends on two key factors: The experience of oneself as spatially belonging to the virtual environment (presence) and of being represented by an avatar (embodiment). It is commonly believed that visuospatial asynchrony of body movements diminishes embodiment. Embodiment and presence have frequently been assessed by the participants’ reaction to threat against the avatar. The validity of such measures has recently been questioned showing that participants can become aware of the research hypotheses, termed demand characteristics. This can lead to changes in participants’ experiences, which are in accordance with researcher’s expectations. Here, we conducted an experiment to test this claim by comparing participants’ ratings in an online experiment to the responses in a VR experiment. In the online experiment, participants watched a video of a person performing the VR experiment combined with the virtual scene they saw. Participants rated their expected embodiment and presence sensations on the same questionnaire in the online and VR experiment. We manipulated movement synchrony (synchronous, asynchronous) and avatar visibility (visible, invisible), and introduced a threat to the avatar (height exposure, control) after each condition. If ratings in both experiments are equivalent, then demand characteristics contribute to the results. As shown in previous studies, participants correctly judged the direction of expected experimental effects. However, ratings in the online and VR experiment differed in size. As compared to the online experiment, ratings in the VR experiment were higher for synchronous movements (only for embodiment), and lower when an avatar was visible. Our results suggest that demand characteristics can only partly explain embodiment and presence as assessed by questionnaires. Additionally, they show the need to control for demand characteristics in future studies examining embodiment and presence.