Abstract

When a vertical bar is moved horizontally behind a narrow vertical slit, there is a time lag between the stimuli to the two eyes. At one particular depth, the stimulus offset for one eye coincides with the stimulus onset for the other eye. Simulation of this particular case on a stereo CRT display revealed that the observer sees a seamless motion of a single target at the depth behind the slit, which is consistent with geometry. If the same trajectory of motion is given to each eye but-in the reversed ocular order, the perception is that of two moving targets just behind the slit. This striking asymmetry between the two cases cannot be explained by changes of convergence or stereopsis based on virtual monocular images. Rather, the visual system seems to take into account the natural- world geometry which constrains the relationship between the direction of motion and order of ocularity. Because the eye of origin information is lost relatively early in cortical processing, the integration process of these two types of information must also occur at early cortical levels.

© 1987 Optical Society of America