STRUCTURE-SENSITIVE
INTEGRATION
IN HUMAN MOTION PERCEPTION |
We live in a world of objects that move. To perceive these
motions correctly, the human visual system cannot simply register motion
signals at different positions on an object contour. In fact, all local
motions are ambiguous (a property of vision that may be called kinematic
indeterminacy). To overcome this ambiguity, local motion signals must
be integrated into a coherent global interpretation. In some cases, the
integration may consist of a simple form of vector
averaging (a structure-blind integration process). Most often, however,
to recover the correct global motion of an object the visual system must
take into account the spatial structure of the optic array. This tutorial
discusses several demonstrations of the role of spatial organization in
motion perception. The barberpole effect
illustrates the role of contour terminators. The chopstick
illusion and the sliding effect illustrate
the role of figure/ground segregation. Motion
stereograms illustrate the role of binocular disparity. Occluded
terminators, Petter plaids, apparent
rest and paradoxical rest illustrate the
role of occlusion, modal, and amodal completion. Invisible
corners illustrate the role of higher-level expectations. Finally,
the
breathing square and illusory
blob effects illustrate that motion integration does not necessarily
obey a rigidity constraint.
created by Fauzia Mosca and Nicola Bruno