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Abstract

The ability to adopt the visuo-spatial perspective of others is fundamental for successful social interactions. Here, we measured how vestibular (Experiment 1) and proprioceptive (Experiment 2) signals influence perspective-taking abilities. For each experiment, participants
completed the “dot-counting task”: they evaluated if a number (0-3) presented at the start of each trial matched or mismatched the number of balls visible from their perspective in a visual scene of a 3D virtual room that followed. A task-irrelevant human avatar or arrow was also present in the center of the room that either shared the same or different viewpoint as the participant’s. This allowed us to examine the likelihood that participants would implicitly adopt the perspective of the object even though they were not required to.
In Experiment 1, participants performed the task while they received low-intensity (1mA)
galvanic vestibular stimulation (GVS). Analysis of reaction times between same and different
viewpoints revealed that GVS reduced the likelihood that participants implicitly adopted the avatar’s perspective, promoting an egocentric viewpoint. In Experiment 2, we manipulated the congruency between the participant’s body orientation (e.g. their entire body was facing the right side of the screen) and that of the avatar. When participants and avatars shared the same body orientation, participants were more likely to implicitly adopt the avatar’s
perspective, resulting in longer response times in the dot-counting task. For both experiments, the effects were not observed for the arrow. Altogether, the results indicate that implicit simulation of another person’s viewpoint requires vestibular and proprioceptive signals.