Physical discomfort and eye movements during arbitrary and optical flow-like motions in stereo 3D contents

Users of stereo 3D technology commonly report physical discomfort during or after exposure of stereo 3D contents. The discomfort has been associated with sensation of arbitrary and optical flow-like self-motion. However, there is no information on whether arbitrary motion induces stronger physical discomfort compared with optical flow-like motion. To address this research gap, we investigate physical discomfort among players and spectators of stereo 3D contents using eye tracking and Simulator Sickness Questionnaire. Thirty participants ( $$N=30$$ N = 30 ) acted as players and spectators of a first-person shooter (FPS) and a car racing game. The FPS and the car racing game produce a sensation of arbitrary and optical flow-like self-motion, respectively. Experimental results show that the FPS game induces more severe physical discomfort than its racing counterpart ( $$p<0.0083$$ p < 0.0083 , with a Bonferroni correction to the p value). We also found that severeness of oculomotor symptoms can be predicted using two eye movements metrics: the amount of fixational eye movements and viewing duration at the center of the screen. Our study implies that one should pay particular attention to different types of self-motion in stereo 3D contents regardless of whether the user controls or solely watches the contents. Our study also suggests that physical discomfort can be reduced by decreasing the frequency of fixational eye movements while prolonging the duration of each fixation at the center of screen.