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Abstract

"Spatial updating" refers to the process that automatically updates our egocentric mental representation of our
immediate surround during self-motions, which is essential for quick and robust spatial orientation. To investigate
the relative contribution of visual and vestibular cues to spatial updating, two experiments were performed in a
high-end Virtual Reality system. Participants were seated on a motion platform and saw either the surrounding
room or a photorealistic virtual model presented via head-mounted display or projection screen. After upright
rotations, participants had to point "as accurately and quickly as possible" to previously-learned targets that were
outside of the current field of view (FOV). Spatial updating performance, quantified as response time, config-uration
error, and pointing error, was comparable in the real and virtual reality conditions when the FOV was
matched. Two further results challenge the prevailing basic assumptions about spatial updating: First, automatic,
reflex-like spatial updating occurred without any physical motion, i.e., visual motion information from a known
scene alone can indeed be sufficient, especially for large FOVs. Second, continuous motion information is not,
in fact, mandatory for spatial updating - merely presenting static images of new orientations proved sufficient,
motivating our distinction between continuous and instant-based spatial updating.