Abstract
Adding viewpoint oscillation to displays increases the likelihood of visually induced self-motion (vection), even though sensory conflict theories predict that it should generate significant and sustained visual-vestibular conflict. This effect has been shown in upright observers, for which the simulated self-motion and oscillation were congruent with or orthogonal to gravity. Here we examined whether this oscillation advantage for vection depends on the orientation of the body with respect to gravity. Observers in upright (seated and standing) and lying (supine, prone, and left side down) postures viewed displays of radial optic flow simulating forward/backward self-motion, with or without horizontal or vertical viewpoint oscillation. Vection magnitude (compared to a reference stimulus), onset, duration, and vection dropouts, were compared among postures. Viewpoint oscillation enhanced vection for all of the body postures tested. Vection also tended to be stronger in upright than in lying postures. Changing body orientation with respect to gravity was expected to alter the degree/saliency of the sensory conflict, and may explain the posture-based differences in vection magnitude. However, this does not explain why the oscillation advantage for vection persisted for all postures. Given that the upright posture and oscillating flow (the norm during real self-motion) improved vection, and lying postures and smooth flow (which are atypical in our experience of self-motion) impaired vection, we conclude that postural and oscillation based vection findings are better explained by ecology.
Meeting abstract presented at VSS 2012