Individual variations in visual control of posture predict vection D Apthorp1, P Stapley2, S Palmisano3 |
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1Research School of Psychology, Australian National University, Australia |
| Visually-induced illusions of self-motion (vection) can be compelling for some people, but there are large individual variations in the strength of these illusions. Do these variations depend, at least in part, on the extent to which people rely on vision to control their postural stability? Using a Bertec balance plate in a brightly-lit room, we measured excursions of the centre of foot pressure (CoP) over a 60-second period with eyes open and with eyes closed, for 13 participants. Subsequently, we collected vection strength ratings for large optic flow displays while seated, using both verbal ratings and online throttle measures. We also collected measures of postural sway (changes in anterior-posterior CoP) in response to the same stimuli while standing on the plate. The magnitude of standing sway in response to expanding optic flow (in comparison to blank fixation periods) was predictive of both verbal and throttle measures for seated vection. In addition, the ratio between eyes-open and eyes-closed CoP excursions (using the area of postural sway) also significantly predicted seated vection for both measures. Interestingly, these relationships were weaker for contracting optic flow displays, though these produced both stronger vection and more sway. |
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