Interaction between size and disparity cues in distance judgements

The human visual system has the ability to use the size of familiar objects as a cue to the object´s depth in the world. With the advancement of Stereoscopic 3D (S3D) displays, objects can now be displayed with differing size and binocular disparity cues to the depth of the object. We tested, for absolute and relative disparity cues, whether the familiar size or disparity cue was the preferred indication of depth. We found that, when only absolute disparity cues are available, the retinal size of a familiar object has a significant effect on its perceived depth, but with relative disparity the binocular disparity was a strong enough cue to depth that size was not a significant cue in determining the depth of the familiar object.