Optical flow from eye movement with head immobilized: "ocular occlusion" beyond the nose.
The point of observation translates with eye movement because it is not coincident with the center of rotation in the eye. "Ocular occlusion" results. The amount of optical structure revealed by eye rotation depends on the distances of the occluding and occluded surfaces. The method of adjustment was used in Expt 1 to investigate the amount of structure detected at distances up to 1 m. In Expt 2, a forced-choice method was used to confirm predictions based on the assumption that the point of observation is in the entrance pupil at 11 mm from the center of rotation. (The location of the point of observation in the eye had not been measured previously.) Experiment 3 investigated the use of ocular occlusion to detect separation of surfaces in depth.