Psychobiologist Roger Sperry discovered that human beings are of two minds. He found that the human brain has specialized functions on the right and left, and that the two sides can operate practically independently.
After receiving a bachelors degree in English literature, he studied psychology and zoology, followed by several years of research at Harvard, Yerkes Laboratory of Primate Biology, and the National Institutes of Health. In 1954, he joined the faculty of Cal Tech where he remained for 30 years.
In the early 1960s, Sperry and colleagues, including Michael Gazzaniga, conducted extensive experiments on an epileptic patient who had had his corpus collosum, the "bridge" between the left and right hemispheres of the brain, split so that the connection was severed. At first the patient seemed quite normal, but experimentation showed certain activities such as naming objects or putting blocks together in a prescribed way could only be done when using one side of the brain or the other. (Since the right eye connects to the left brain, the left hand to the right brain, and so on throughout the body, the stimulus would be given to the side of the body opposite the brain hemisphere being tested.) These abilities were not absolute, but it seemed that the left hemisphere specialized in language processes and the right is dominant in visual-construction tasks.
Sperry's work helped chart a map of the brain and opened whole fields of psychological and philosophical questions. Sperry received the Nobel prize in 1981.