It is well known that some viewers experience visual discomfort when looking at stereoscopic displays. One of the factors that can give rise to visual discomfort is the presence of large horizontal disparities. The relationship between excessive horizontal disparity and visual comfort has been well documented for the case in which disparity magnitude does not change across space and time, e.g. for objects in still images. Much less is known about the case in which
disparity magnitude varies over time, e.g., objects moving in depth at some velocity. In this study, we investigated the relationship between binocular disparity, object motion and visual comfort using computer-generated stereoscopic video sequences. Specifically, viewers were asked to rate the visual comfort of stereoscopic sequences that had objects moving periodically back and forth in depth. These sequences varied with respect to the number, size, position in depth, and velocity of movement of the objects in the scene. The results indicate that change in disparity magnitude over time might be more important in determining visual comfort than the absolute magnitude of the disparity per se. The results also suggest that rapid switches between crossed and uncrossed disparities might negatively affect visual comfort.