The Journal of Neuroscience, August 1, 2000, 20(15):5885-5897
Occlusion and the Interpretation of Visual Motion: Perceptual and
Neuronal Effects of Context
Robert O.
Duncan1,
Thomas D.
Albright1, 2, and
Gene R.
Stoner1
1 Systems Neurobiology Laboratories and
2 Howard Hughes Medical Institute, The Salk Institute for
Biological Studies, La Jolla, California 92037
Visual motion can be represented in terms of the dynamic visual
features in the retinal image or in terms of the moving surfaces in the
environment that give rise to these features. For natural images, the
two types of representation are necessarily quite different because
many moving features are only spuriously related to the motion of
surfaces in the visual scene. Such "extrinsic" features arise at
occlusion boundaries and may be detected by virtue of the
depth-ordering cues that exist at those boundaries. Although a number
of studies have provided evidence of the impact of depth ordering on
the perception of visual motion, few attempts have been made to
identify the neuronal substrate of this interaction. To address this
issue, we devised a simple contextual manipulation that decouples
surface motion from the motions of visual image features. By altering
the depth ordering between a moving pattern and abutting static
regions, the perceived direction of motion changes dramatically while
image motion remains constant. When stimulated with these displays,
many neurons in the primate middle temporal visual area (area MT)
represent the implied surface motion rather than the motion of retinal
image features. These neurons thus use contextual depth-ordering
information to achieve a representation of the visual scene consistent
with perceptual experience.
Key words:
motion perception; psychophysics; neurophysiology; binocular disparity; extrastriate; monkey
Copyright © 2000 Society for Neuroscience 0270-6474/00/20155885-13$05.00/0
