Vision: A Computational Investigation into the Human Representation and Processing of Visual Information
by David Marr
W.H. Freeman, 397 pp., $21.95 (paper)
Most of us seeing the kettle upside down on the kitchen floor would react by saying, “How did that get there?” or, “The cat’s been at it again!” We would not wonder what we were seeing. But not everyone is so fortunate. In 1973, the English neurologist Elizabeth Warrington told an MIT audience about patients with damage to the right side of the brain who had no trouble identifying water buckets and similar objects in side views, yet were unable to identify them from above. Another group of patients with damage to the brain’s left side readily identified the water bucket from both views of it.
Among those in the MIT audience was the young English mathematician and neuroscientist David Marr (1945–1980), who recounts the story in his postnumously published book, Vision. Marr died of leukemia in November 1980. Because of his illness, he was forced to write his book a few years earlier than he had planned. Vision is a brilliant synthesis of the recent work on perception that has deep philosophical and psychological implications. It is the best account I know of a new approach to the study of brain function, and its closing dialogue should be read by anyone interested in brains, minds, and machines.
Warrington’s talk suggested to Marr that the brain stored information about the use and functions of objects separately from information about their shape, and that our visual system permits us to recognize objects even though we cannot name them or describe their function. At the time, it was generally believed that seeing required enormous amounts of previously acquired knowledge. But during the 1970s Marr and a small group of colleagues at the Artificial Intelligence Laboratory of MIT succeeded in largely undermining this view. What emerged was a theory of perception that integrated work in neurophysiology, psychology, and artificial intelligence and that gives us some of the most profound insights into the nature and functioning of the brain we have yet had.
Nineteenth-century anatomists spent much time arguing whether or not specific functions such as speaking, reading, and writing were situated in discrete areas of the brain. Franz Gall, whose name is most closely associated with the pseudoscience of phrenology, had argued that everything from love to religion had its own anatomical place in the cerebral cortex. When a given talent or character trait excelled the normal, a well-localized bump appeared on the skull that phrenologists and the more open-minded anatomists could find with little difficulty. The scientific establishment of the day was not persuaded by these arguments. Until 1860 most scientists viewed the brain as a whole whose functional capacities could not be compartmentalized.
After 1860 the view that function was localized became dominant. Paul Broca had found a well-circumscribed area in the left side of the brain that appeared to control crucial aspects of speech. Direct stimulation of the cerebral cortex showed that sensory and motor function of every part of the body was under the …