David Badcock

Department of Psychology, University of Western Australia, Nedlands, WA, Australia

Functional Sub-streams in Visual Motion Perception: Explanatory Concept and Theoretical Blinker

It is common to refer to two streams of processing within the hierarchy of cortical areas in the human visual system: a motion- and a form-processing stream. A frequent focus in this framework has been on the extent to which the two streams are further sub-divided. More recently attention has turned to the extent to which the streams interact in vision.

One concerted research effort has focused on whether there are sub-streams within the motion-processing system selectively sensitive to first- and second-order stimulus properties. I will present a series of experiments, designed to tap different levels of the motion-processing hierarchy, which show that for at least one specific pair of first- and second-order properties, motion-processing receives separate inputs at all levels tested. In this case it is useful to think of functional sub-streams.

Following this, a series of experiments will be presented which question the functional independence of form and motion processing by showing that form-processing mechanisms can provide a significant input to the motion-system. Sequences of Glass patterns will be displayed that have a common global form but are uncorrelated with each other. These sequences contain motion signals of random velocity but the common global form shapes the perceived motion direction. Thus the independence of the form and motion streams seems to have been overstated.

This page was last updated on 16 Feb 2001.

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