It appears as a free access on Association for Research in Vision and Ophthalmology (ARVO).
Building on principles of binocular geometry established by Leonardo da Vinci, Drs.Kevin Brooks and Barbara Gillam of the University of New South Wales in Sydney, Australia, conducted a series of experiments in which observers were asked to match
the amplitude of motion in depth seen through stereoscopic stimuli presented on two computer monitors. Dynamic versions of a monocular gap stereogram were used to produce a percept of motion in depth from changes in the locations of unmatched features, despite a lack of any previously known cues to 3D motion. The studies showed that while the established cues of changing disparity (CD) and interocular velocity difference (IOVD) are involved in the percept of motion in depth for features visible in both eyes, a new cue, dynamic half-occlusion, is used when unmatched features are observed.