Skip navigation
Paperback | $61.00 Short | £45.95 | ISBN: 9780262621311 | 640 pp. | 5.9 x 8.9 in | April 1999

Symmetry, Causality, Mind



Leyton observes that the mind assigns to any shape a causal history explaining how the shape was formed. We cannot help but perceive a deformed can as a dented can. Moreover, by reducing the study of shape to the study of symmetry, he shows that symmetry is crucial to our everyday cognitive processing. Symmetry is the means by which shape is converted into memory.

Perception is usually regarded as the recovery of the spatial layout of the environment. Leyton, however, shows that perception is fundamentally the extraction of time from shape. In doing so, he is able to reduce the several areas of computational vision purely to symmetry principles. Examining grammar in linguistics, he argues that a sentence is psychologically represented as a piece of causal history, an archeological relic disinterred by the listener so that the sentence reveals the past. Again through a detailed analysis of art he shows that what the viewer takes to be the experience of a painting is in fact the extraction of time from the shapes of the painting. Finally he highlights crucial aspects of the mind's attempt to recover time in examples of political subjugation.

About the Author



“This is a remarkable book. Its claim is that perception is none other than the recovery of causal history. One cannot but be struck by the depth, novelty, and brilliance of Leyton's accounts, page after page, of even the most minute and ordinary of perceptual phenomena—claims which contradict virtually every previous treatment of these phenomena.”
Eleanor Rosch , Professor, University of California, Berkeley