Pioneering vision researcher Russell De Valois has died at 76
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BERKELEY – Russell L. De Valois, a professor of psychology and vision science at the University of California, Berkeley, whose experiments resolved a century-old debate about color vision and generated new ideas about spatial vision, died Saturday, Sept. 20, as the result of an automobile accident.
De Valois, 76, was a passenger in a car that crashed in Rock Springs, Wyo., on Sept. 10. He lapsed into a coma and died 10 days later at the University of Utah Medical Center in Salt Lake City. His wife, Karen K. De Valois, also a UC Berkeley professor of psychology and vision science, was injured in the accident as well, but has been released from the hospital.
"He was a pioneer in trying to explain how psychophysical phenomena, such as how we discriminate colors and describe subjective differences in color, are related to neuronal activity," said longtime colleague and collaborator Eugene Switkes, professor of chemistry at UC Santa Cruz and an affiliate of UC Berkeley's School of Optometry.
In the past few years, De Valois had collaborated with his wife - "they were close, but complementary, intellectual colleagues," Switkes said - on a model which further describes the details of color vision.
At the time of his death, Russell De Valois was working on a new theory of how brain cells encode information about motion.
"Typical of Russ, it's an outrageous theory that probably has more truth than outrage to it," said Switkes.
De Valois, who also held appointments in the campus's School of Optometry and Helen Wills Neuroscience Institute, sometimes used humans and monkeys in behavioral visual tests, called psychophysical studies. More often, his experiments involved inserting electrodes into the brains of macaques and cats to determine how individual brain cells respond to color, form, images or movement. He pioneered recording from individual neurons in subcortical brain structures, developing methods that are now widely used in laboratories around the world.
"He tried to correlate electrical events in the brain with actual behavior to discover how we see color and perceive spatial information," Switkes said. "He was always interested in what the cells can tell us - 'listening to what the cells had to say.'"
These animal studies, which De Valois continued until just a few years ago, could contribute to the development of visual prostheses for the blind, Switkes said.
"People, including at least one of Russ's former students, are working on prosthetic devices that stimulate cells in the brain's visual cortex to create visual sensation and, hopefully, vision," he said. "The first stage in making this work is understanding what these cells do, and that's what Russ's contribution was."
According to his colleagues, De Valois often remarked, "Before you can fix an instrument, you have to understand how it is supposed to work."
De Valois' UC Berkeley colleagues spoke with admiration and affection of his great intellect and his gift for teaching.
"He was truly a great man, with one of the most clear and concise minds I've ever seen," said Ervin Hafter, a colleague in the psychology department. "He was fabulous as a mentor to graduate students, and had become a 'grand old man' of the department."
"Russ was a great colleague," added Dennis M. Levi, dean of the School of Optometry. "He was a brilliant and accomplished scientist, an incredibly dedicated teacher, and a wonderful, warm human being. He will be sorely missed by all whose lives were touched by him."
De Valois was born in Ames, Iowa, on Dec. 15, 1926, and followed his parents to India, where they served as missionaries for the Dutch Reformed Church. He attended school in Kodaikanal, India, returning to the United States in 1943 to enter Oberlin College. After obtaining his A.B. in zoology and physiology in 1947 and his M.A. in psychology in 1948, he entered the University of Michigan, earning his Ph.D. in physiological psychology in 1952.
Following research and teaching stints at the University of Michigan and a post-doctoral appointment in Germany, he joined the faculty at Indiana University in Bloomington, where he first made a name for himself by describing the brain mechanisms behind color vision.
Based on single-cell recordings from a region of the thalamus called the lateral geniculate nucleus (LGN), he showed how monkeys, and by extension humans, perceive many different colors despite the fact that the eyes' color-sensing cones contain only three types of broadly selective photoreceptors. He found that cells in the brain may be activated by light of one color and cease firing when presented with a different color. The brain cells do a sort of "algebra," he said, to calculate the wavelength region of light and allow us to perceive the full range of colors. His discovery of neurons with "opponent color organization" helped to explain our perception of the primary colors and color combinations, and resolved arguments dating from the 19th century about color perception.
In careful experiments, he subsequently showed that what he discovered in monkeys applied also to the early stages of color processing in humans.
"The understanding of the nature of basic information about color at the levels of the cone receptors and the LGN, and the knowledge about how the simple cone information is processed by the neurons of the color vision pathway, are two critical contributions that Dr. Russell De Valois has provided vision science, giving it its first true insight into the mechanism of color vision," wrote Cynthia M. Langley of Indiana University in 1989 upon De Valois' receipt of the prestigious 1988 Edgar D. Tillyer Medal, one of the highest honors awarded by the Optical Society of America.
De Valois and his students also shed light on human color-blindness by showing that certain species of New World monkeys showed impaired red-green vision similar to a type of red-green impairment found in a small percentage of human males.
In 1968, De Valois joined the faculty at UC Berkeley, where he continued his color vision research and also began looking at perception of spatial information and how it is analyzed and encoded in the brain. Often in collaboration with his wife, he concentrated on the early stages of spatial vision, in particular how our perception varies depending on the graininess or resolution of what we see. They found, in analogy with color vision, that brain cells are tuned to specific bands of spatial frequency and orientation.
This so-called spatial frequency analysis is exploited in making the connection between how our brain perceives an image and how JPEG pictures are often coded and transmitted across the Internet - first appearing as a coarse-grained image, and later filled in with fine detail. Much of this work was conducted on cats, which, though essentially colorblind, provide a good model for human spatial vision.
The couple also looked at how color and luminance variations contribute to spatial perception. They published an influential book, "Spatial Vision," in 1988 that summarized two decades of work by vision researchers.
"The impact of this work extends beyond the community of physiologists and psychologists studying vision," said Anthony J. Adams, professor and former dean of UC Berkeley's School of Optometry. "The strategies used by the human visual system to encode color, pattern and movement, as revealed by De Valois and colleagues, are being employed by engineers currently developing economic image encoding schemes for the United States HDTV (high definition television) initiative."
At the time of his death, De Valois and his wife were working on a companion book, to be called "Color Vision," and a multistage model of color perception.
Away from the lab, De Valois enjoyed life to the fullest, Hafter said. "Whether hiking in the mountains or skiing or traveling to favorite places or eating favorite foods or playing tennis with friends or driving his beloved red sports car," he said, "every act of living was an adventure."
De Valois was a member of the National Academy of Sciences and a recipient of various awards, including the Tillyer Medal of the Optical Society of America, the Warren Medal of the Society of Experimental Psychologists and the Distinguished Scientific Contribution Award of the American Psychological Association. He was a Fulbright Fellow, a William James Fellow of the American Psychological Society and a fellow of the American Association for the Advancement of Science.
At the Optical Society of America meeting next week in Arizona, two special symposia will be dedicated to DeValois' career in honor of his work in the psychophysics and physiology of vision.
De Valois is survived by his wife of 34 years, Karen (Kennedy) De Valois; two children with Karen, Chad of Oakland and Kamala De Valois of Berkeley; three children by a previous marriage, Geoffrey of Los Angeles, Gregory of San Jose and Gordon of Oakland; a son-in-law, Michael Ellis, of Berkeley; sisters Margaret Van Anrooy of Woodland Park, Colo., and Francine Schramm of Brookfield, Wisc.; a brother, John James De Valois Jr., of Redwood City, Calif.,; two grandchildren; and numerous nieces and nephews.
Plans are being made for a memorial service.