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Abstract

Passive movement through an environment typically involves a combination of several signals, including, visual and vestibular information. Recently it has been shown that if different sensory signals are spatially or temporally discrepant they may not combine in a statistically optimal fashion; however, this has not been evaluated for visual-vestibular integration. In this study, participants were seated on a Stewart motion platform and judged which of two heading intervals was more to the right. Motion/heading information (displacement, velocity and acceleration) was presented via stereo visual information alone, vestibular information alone or both cues combined. In the combined condition, the visual motion profile and the vestibular motion profile differed, therefore creating a discrepancy between the two signals. Specifically, the vestibular motion consisted of a raised cosine velocity profile, while the visual motion consisted of a constant velocity profile. The results show that visual-vestibular inputs
combine in a statistically optimal fashion even if the motion profiles do not correspond. Considering that, for linear motion the visual system is more sensitive to velocity and displacement than acceleration, while the vestibular system is a predominantly acceleration-based sensory system, different components of the motion profile may be optimally detected by each of the individual sensory systems.