- 1913 – Roger Wolcott Sperry, American neuropsychologist and neurobiologist, Nobel Prize laureate (d. 1994).
- 1985 – Donald O. Hebb, Canadian psychologist and academic (b. 1904).
Roger Wolcott Sperry
Roger Wolcott Sperry (20 August 1913 to 17 April 1994) was an American neuropsychologist, neurobiologist and Nobel laureate who, together with David Hunter Hubel and Torsten Nils Wiesel, won the 1981 Nobel Prize in Physiology and Medicine for his work with split-brain research. A Review of General Psychology survey, published in 2002, ranked Sperry as the 44th most cited psychologist of the 20th century.
Sperry went to Hall High School in West Hartford, Connecticut, where he was a star athlete in several sports, and did well enough academically to win a scholarship to Oberlin College. At Oberlin, he was captain of the basketball team, and he also took part in varsity baseball, football, and track. He also worked at a café on campus to help support himself. Sperry was an English major, but he took an Intro to Psychology class taught by a Professor named R.H. Stetson who had worked with William James, the father of American Psychology. This class sparked Sperry’s interest in the brain and how it can change. Stetson was disabled and had trouble getting around so Sperry would help him out by driving him to and from wherever he needed to go. This included taking Stetson to lunch with his colleagues. Sperry would just sit at the end of the table and listen to Stetson and his colleagues discuss their research and other psychological interests. This increased Sperry’s interest in Psychology even more and after he received his undergraduate degree in English from Oberlin he decided to stay and get his master’s degree in Psychology. He received his bachelor’s degree in English in 1935 and a master’s degree in psychology in 1937. He received his Ph.D. in zoology from the University of Chicago in 1941, supervised by Paul A. Weiss. Sperry then did postdoctoral research with Karl Lashley at Harvard University though most of his time was spent with Lashley at the Yerkes Primate Research Centre in Orange Park, Florida.
In 1942, Sperry began work at the Yerkes Laboratories of Primate Biology, then a part of Harvard University. There he focused on experiments involving the rearranging of motor and sensory nerves. He left in 1946 to become an assistant professor, and later associate professor, at the University of Chicago. In 1949, during a routine chest x-ray, there was evidence of tuberculosis. He was sent to Saranac Lake in the Adironack Mountains in New York for treatment. It was during this time when he began writing his concepts of the mind and brain, and was first published in the American Scientist in 1952. In 1952, he became the Section Chief of Neurological Diseases and Blindness at the National Institutes of Health and finished out the year at the Marine Biology Laboratory in Coral Gables, Florida. Sperry went back to The University of Chicago in 1952 and became an Associate Professor of Psychology. He was not offered tenure at Chicago and planned to move to Bethesda, Maryland but was held up by a delay in construction at the National Institutes of Health. During this time Sperry’s friend Victor Hepburn invited him to lecture about his research at a symposium. There were professors from the California Institute of Technology in the audience of the symposium who, after listening to Sperry’s lecture, were so impressed with him they offered him a job as the Hixson Professor of Psychobiology. In 1954, he accepted the position as a professor at the California Institute of Technology (Caltech as Hixson Professor of Psychobiology) where he performed his most famous experiments with Joseph Bogen, MD and many students including Michael Gazzaniga.
Under the supervision of Paul Weiss while earning his Ph.D. at the University of Chicago, Sperry became interested in neuronal specificity and brain circuitry and began questioning the existing concepts about these two topics. He asked the simple question first asked in his Introduction to Psychology class at Oberlin: Nature or nurture? He began a series of experiments in an attempt to answer this question. Sperry crosswired the motor nerves of rats’ legs so the left nerve controlled the right leg and vice versa. He would then place the rats in a cage that had an electric grid on the bottom separated into four sections. Each leg of the rat was placed into one of the four sections of the electric grid. A shock was administered to a specific section of the grid, for example the grid where the rat’s left back leg was located would receive a shock. Every time the left paw was shocked the rat would lift his right paw and vice versa. Sperry wanted to know how long it would take the rat to realize he was lifting the wrong paw. After repeated tests Sperry found that the rats never learned to lift up the correct paw, leading him to the conclusion that some things are just hardwired and cannot be relearned. In Sperry’s words, “no adaptive functioning of the nervous system took place.” During Sperry’s postdoctoral years with Karl Lashley at Harvard and at the Yerkes Laboratories of Primate Biology in Orange Park, Florida, he continued his work on neuronal specificity that he had begun as a doctoral student and initiated a new series of studies involving salamanders. The optic nerves were sectioned and the eyes rotated 180 degrees. The question was whether vision would be normal after regeneration or would the animal forever view the world as “upside down” and right-left reversed. Should the latter prove to be the case, it would mean that the nerves were somehow “guided” back to their original sites of termination. Restoration of normal vision (i.e. “seeing” the world in a “right-side-up” orientation) would mean that the regenerating nerves had terminated in new sites, quite different from the original ones. The animals reacted as though the world was upside down and reversed from right to left. Furthermore, no amount of training could change the response. These studies, which provided strong evidence for nerve guidance by “intricate chemical codes under genetic control” (1963) culminated in Sperry’s chemoaffinity hypothesis (1951).
Sperry later served on the Board of Trustees and as Professor of Psychobiology Emeritus at California Institute of Technology. The Sperry Neuroscience Building at Oberlin College was named in his honour in 1990.
Donald O. Hebb
Donald Olding Hebb FRS (22 July 1904 to 20 August 1985) was a Canadian psychologist who was influential in the area of neuropsychology, where he sought to understand how the function of neurons contributed to psychological processes such as learning. He is best known for his theory of Hebbian learning, which he introduced in his classic 1949 work The Organisation of Behaviour. He has been described as the father of neuropsychology and neural networks. A Review of General Psychology survey, published in 2002, ranked Hebb as the 19th most cited psychologist of the 20th century. His views on learning described behaviour and thought in terms of brain function, explaining cognitive processes in terms of connections between neuron assemblies.