Study on the ocular parallax as a monocular depth cue induced by small eye movements during a gaze

We measured eye movements to examine the effect of ocular parallax induced by small eye movements during a gaze. We analyzed gazing positions, sight line shifts and duration time of a gaze. We obtained the following results. When humans gaze at visual target on a planar surface in some depth, (1) gazing positions are distributed in bounded region to a certain extent; (2) sight line shifts are not distributed along any specific directions. On the other hand, when humans gaze at surfaces which are located in different depths, (1) gazing positions are distributed more closely to each other for the further surface than the nearer surface; (2) sight line shifts tend to increase the shifts between two surfaces. These results indicate the possibility of using the effect of ocular parallax as a cue of depth perception.