Hebb, Donald Olding (1904–1985)
Hebb was very well grounded in the psychological theories of the early twentieth century by his graduate training at McGill, Chicago, and Harvard before his almost unique experience of measuring the mental capacities of human patients with surgical brain lesions. This impressed upon him the importance of the brain for determining behavior. He recognized that, although the proponents of the mainstream stimulus–response theories claimed to reject neural explanations, they in fact based their theories on a ridiculously simplified brain in which sensory input went directly to motor output. He therefore developed a behavior theory that involved a more realistic model of the brain and in doing so, brought about a profound change in the course taken by psychology.