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Abstract

Self-motion through an environment is a composite of signals such as vision and vestibular cues. Recently, it has been shown that visual-auditory cues and visual-haptic cues combine in a statistically optimal fashion. We asked what role does stereo vision play in optimal integration of visual and vestibular cues for linear heading. Participants performed the task in visual alone, vestibular alone or combined visual-vestibular (self-motion). The conditions were grouped into two experiments; bi-ocular, 2-D experiment and stereo, 3-D experiment. Participants were seated on a Stewart motion platform and presented with two motions consisting of a standard heading of straight ahead and a comparison heading and judged which movement was more to the right. From the responses individual JND were calculated (i.e., reliability measure). In the 2-D experiment 40 of participants’ self-motion reliability was worse than their most reliable unimodal cue, thus violating optimal cue combination. In the 3-D experiment all subjects self-motion reliability was not statistically different from the optimal predicted self-motion and therefore more reliable than either unimodal cue. These results can be evaluated with respect to a neuronal population model. These findings show that visual-vestibular cues combine in statistically optimal fashion with the caveat of stereo visuals.