David Rumelhart Dies at 68; Created Computer Simulations of Perception

David E. Rumelhart, whose computer simulations of perception gave scientists some of the first testable models of neural processing and proved helpful in the development of machine learning and artificial intelligence, died Sunday in Chelsea, Mich. The cause was complications of Pick's disease, an Alzheimer's-like disorder from which he had suffered for more than a decade, his son Karl said. When Dr. Rumelhart, a psychologist, began thinking in the 1960s about how neurons process information, the field was split into two camps that had little common language: biologists, who focused on neurons and brain tissue; and cognitive psychologists, who studied far more abstract processes, like reasoning skills and learning strategies. By starting small -- showing, for instance, that the brain's ability to recognize a single letter was greatly influenced by the letters around it -- Dr. Rumelhart and his colleague Jay McClelland, around 1980, built computer programs that roughly simulated perception. Later, he devised an algorithm that allowed computer programs to learn how to perceive.