title: A Pursuit Theory Account for the Perception of Common Motion in Motion Parallax.
abstract: The visual system uses an extraretinal pursuit eye movement signal to disambiguate the perception of depth from motion parallax. Visual motion in the same direction as the pursuit is perceived nearer in depth while visual motion in the opposite direction as pursuit is perceived farther in depth. This explanation of depth sign applies to either an allocentric frame of reference centered on the fixation point or an egocentric frame of reference centered on the observer. A related problem is that of depth order when two stimuli have a common direction of motion. The first psychophysical study determined whether perception of egocentric depth order is adequately explained by a model employing an allocentric framework, especially when the motion parallax stimuli have common rather than divergent motion. A second study determined whether a reversal in perceived depth order, produced by a reduction in pursuit velocity, is also explained by this model employing this allocentric framework. The results show than an allocentric model can explain both the egocentric perception of depth order with common motion and the perceptual depth order reversal created by a reduction in pursuit velocity. We conclude that an egocentric model is not the only explanation for perceived depth order in these common motion conditions.
authors.affiliation: Center for Visual and Cognitive Neuroscience, Department of Psychology, North Dakota State University, Fargo, ND, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Ratzlaff
authors.affiliation: Center for Visual and Cognitive Neuroscience, Department of Psychology, North Dakota State University, Fargo, ND, USA mark.nawrot@ndsu.edu.
authors.forename: Mark
authors.initials: M
authors.lastname: Nawrot
mesh_terms: D000328:Adult; D003867:Depth Perception / Q000502:physiology*; D006801:Humans; D009039:Motion Perception / Q000502:physiology*; D011698:Pursuit, Smooth / Q000502:physiology*; D015357:Vision Disparity / Q000502:physiology*; D055815:Young Adult
keywords: common motion; depth perception; motion parallax; pursuit eye movements; visual perception