Hiroyasu Ujike

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The lower parallactic depth threshold is determined by (a) the ratio of relative image velocity to head velocity when the head moves fast (>13 cm/s) and (b) the motion threshold when the head moves slow (<13 cm/s). These two results are explained by a single system that codes the ratio of relative image velocity to head velocity, using the same image(More)
Visual motion often provokes vection (the induced perception of self-motion) and postural movement. Postural movement is known to increase during vection, suggesting the same visual motion signal underlies vection and postural control. However, self-motion does not need to be consciously perceived to influence postural control. Therefore, visual motion(More)
To reduce possibilities of visually-induced motion sickness caused by animations, video games and movies, we need to develop an evaluation method of visually-induced motion sickness. Our previous results have shown that virtual roll motion had the most effective for producing the sickness. In the present study, we focused on the effectivity of image types,(More)
Yoking the movement of the stimulus on the screen to the movement of the head, we examined visual stability and depth perception as a function of head-movement velocity and parallax. In experiment 1, for different head velocities, observers adjusted the parallax to find (a) the depth threshold and (b) the concomitant-motion threshold. Between these(More)
We examined Wheatstone's (1838 Philosophical Transactions of the Royal Society of London 128 371-394) claim that images falling on retinally corresponding points can be seen in two different directions, in violation of Hering's law of identical visual direction. Our analyses showed that random-dot stereograms contain stimulus elements that are conceptually(More)
Prolonged exposure to computer animation can cause undesirable side effects (e.g., the Pokémon incident: Takahashi and Tsukahara (1998) and motion sickness with computer games: de Waard et al., 2003). In 2005, the International Organization for Standardization (ISO) published the ISO workshop agreement 3 (IWA 3) that called for more guidelines on image(More)
When observers binocularly fixate on an inclined sheet of paper with equally spaced dots, an apparent "staircase" is seen. We varied the inclination of the sheet, the spacing among the dots, and the viewing distance. The results indicate that (1) as the space and the inclination decreased, the number of apparent steps increased and the height of apparent(More)