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Updated: Jul 30, 2026

Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns
Published on: May 12, 2019
Perceptual dimorphism in visual motion from stationary patterns
1Department of Psychology, Brown University, Providence, RI 02912, USA. galit_naor@brown.edu
Abstract:
Fraser and Wilcox [1979 Nature (London) 281 565-566] devised a series of complex stationary patterns that provoked episodes of compelling illusory motion, but only in about two-thirds of people tested. Using simplified versions of their stimuli, we have confirmed their claim of perceptual dimorphism. We show that the strength of the illusory motion depends upon stimulus duration, eccentricity, and contrast. The illusory motion does not require fluctuations in accommodation, as has been suggested for some other forms of illusory motion. Finally, we consider the relation of Fraser-type motion to other forms of illusory motion.
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