Hering's laws imply that the visual direction assigned to a binocularly visible object is based on the oculocentric positions of the object in both eyes; the direction assigned to a monocularly visible object is based on its oculocentric position in that eye. It is interesting to consider how these laws apply near an occluder. Near the vertical edge of an opaque occluder, some regions of a far surface are visible to one eye only and other regions are visible to both eyes; the demarcation is created by the edge of the occluder and depends on the distance to the occluder and the far surface. If Hering's laws applied in this situation, we would expect spatial discontinuities in perceived visual directions near the edge of the occluder: in the monocular zone, the assignment of direction would be made by one eye's image and in the binocular zone, right next to the monocular zone, the assignment would be made by both eyes' images. Because of this switch in the eyes controlling the assignment, spatial discontinuities in perceived direction are expected. We measured perceived visual direction near an occluding edge and found spatial distortions, but no discontinuities. We measured the horizontal and vertical spatial extents of the distortions and inferred how the inputs to the two eyes are weighted when one eye's view is occluded, nearly occluded, and not nearly occluded. In conclusion, the visual system seems to avoid spatial discontinuities in perceived visual direction that could otherwise occur near an occluder by varying the weights attached to each eye's input depending on target position relative to the occluding edge.
