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Updated: Aug 15, 2026

Methods to Explore the Influence of Top-down Visual Processes on Motor Behavior
Published on: April 16, 2014
Perception of geometric illusions in hemispatial neglect
1Department of Neurology, University of California at Davis, Martinez 94553, USA. tonyro@ucdavis.edu
Abstract:
A patient with left hemispatial neglect, while completely unaware of features on the left side of figures, nevertheless perceived geometric illusions dependent on these features. Bisection errors were amplified not only by increasing line length, but also by perceived line length induced by these illusions. Bisection of Judd illusion figures was as much influenced by neglected features on the left as by perceived features on the right. These observations demonstrate that geometric illusions are generated through preattentive processes. They also suggest that in visual neglect there may be preattentive processing of location as well as shape information.
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