Horizontal fixation point oscillation and simulated viewpoint oscillation both increase vection in depth

Abstract

Previous research has shown that vection can be enhanced by adding horizontal simulated viewpoint oscillation to radial flow. Adding a horizontally oscillating fixation target to purely radial flow induces a superficially similar illusion of self-motion, where the observer's perceived heading oscillates left and right as their eyes pursue the moving target. This study compared the vection induced by these two conditions for the first time. 15 s optic flow displays (47° wide by 37° high) simulated constant velocity forward self-motion either with/without horizontal simulated viewpoint oscillation (±6.8 deg; 0.58 – 1 Hz). Stationary subjects viewed these displays while fixating a target that either oscillated sinusoidally from the left to the right (±6.8 deg; 0.58 – 1 Hz) or remained fixed at the centre of the screen. We found that fixation point oscillation and simulated viewpoint oscillation both improved the vection induced by radial flow (i.e. stronger ratings, shorter onsets and longer durations of vection relative to no oscillation control displays). Neither vection advantage could be explained in terms of differences in perceived scene rigidity or motion adaptation (based on the subjects' subjective ratings and motion aftereffect durations). Thus, we conclude that both oscillation based vection advantages were generated by the increased global retinal motion and retinal slip. Meeting abstract presented at VSS 2012