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Lashley, Karl Spencer

        Health | Great Psychologists

Lashley, Karl Spencer (1890-1958) was an American psychologist who researched the correlation between brain function and learning. He is considered the founder of neuropsychology.

Lashley earned a Ph.D. degree in zoology at Johns Hopkins University in 1914. He became interested in the brain's functions through his work with American psychologist John Broadus Watson and began a post-doctoral study of vertebrate behavior that continued until 1917.

At the University of Minnesota, where he became an instructor in psychology in 1920, Lashley carried out extensive laboratory research on the brains of rats. He was promoted to full professor in 1924. In 1926, he joined the faculty of the University of Chicago, and in 1935 he accepted a research professorship in neuropsychology at Harvard University. Beginning in 1942, he also served as director of the Yerkes Laboratories of Primate Biology in Orange Park, Florida.

Lashley studied the role of the brain's cerebral cortex in memory and learning. One of his main objectives was to locate what he called the engram, or neural component of memory. He initially assumed that any specific memory or sensory perception would be associated with a localized point within the cortex. He discovered that this was untrue. Rather, in certain types of learning, the cortex functioned in a holistic way.

He further found that when parts of the cortex were removed or damaged, certain abilities associated with those parts often remained. The healthy areas adapted by taking on the functioning of the damaged area, a concept Lashley named equipotentiality. These findings of the cortex's ability to function as a whole led to his theories of learning, which replaced the prevailing theory of localized cortical functioning. He outlined those theories in Brain Mechanisms and Intelligence (1964).