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Intact “biological motion” and “structure from motion” perception in a patient with impaired motion mechanisms: A case study

Published online by Cambridge University Press:  02 June 2009

Lucia M. Vaina
Affiliation:
Intelligent Systems Laboratory, College of Engineering and the Department of Neurology, School of Medicine, Boston UniversityHarvard-Massachusetts Institute of Technology, Division of Health Sciences and Technology
Marjorie Lemay
Affiliation:
Brigham and Women's Hospital, Harvard Medical school
Don C. Bienfang
Affiliation:
Brigham and Women's Hospital, Harvard Medical school
Albert Y. Choi
Affiliation:
Intelligent Systems Laboratory, College of Engineering and the Department of Neurology, School of Medicine, Boston University
Ken Nakayama
Affiliation:
Smith Kettlewell Eye Research Institute

Abstact

A series of psychophysical tests examining early and later aspects of image-motion processing were conducted in a patient with bilateral lesions involving the posterior visual pathways, affecting the lateral parietal-temporal-occipital cortex and the underlying white matter (as shown by magnetic resonance imaging studies and confirmed by neuro-ophthalmological and neuropsychological examinations). Visual acuity, form discrimination, color, and contrast-sensitivity discrimination were normal whereas spatial localization, line bisection, depth, and binocular stereopsis were severely impaired. Performance on early motion tasks was very poor. These include seeing coherent motion in random noise (Newsome & Paré, 1988), speed discrimination, and seeing two-dimensional form from relative speed of motion. However, on higher-order motion tasks the patient was able to identify actions from the evolving pattern of dots placed at the joints of a human actor (Johansson, 1973) as well as discriminating three-dimensional structure of a cylinder from motion in a dynamic random-dot field. The pattern of these results is at odds with the hypothesis that precise metrical comparison of early motion measurements is necessary for higher-order “structure from motion” tasks.

Information

Type
Research Article
Copyright
Copyright © Cambridge University Press 1990

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