Effects of Viewpoint Jitters Onf Roll Vection

It has been revealed that random viewpoint jitters or periodical viewpoint oscillation superimposed in visual stimulus which simulates the observer's self-motion can enhance visually induced self-motion perception (vection), even if there are sustained conflicts between visual and vestibular information. The effects of jitter/oscillation have been confirmed both using forward self-motion induced by expanding display and horizontal linear self-motion induced laterally moving visual pattern. In the present investigation, we examined whether jitter/oscillation advantage would affect visually induced self-rotation (roll vection) induced by rotating visual pattern. In psychophysical experiments with 12 undergraduate participants, we compared perceived strength of roll vection between the stimulus conditions where simulated viewpoint jitters were superimposed or not. The results indicated that viewpoint jitters significantly weakened strength of perceived self-rotation. On the other hand, random roll component superimposed in pure radial expanding pattern can enhance illusory forward self-motion. These results suggest that the effects of viewpoint jitter would affect differently on linear vection induced by expanding optical flow and circular vection induced by visual rotation.