LASHLEY, KARL SPENCER

(b. Davis, West Virginia, 7 June 1890; d. Poitiers, France, 7 August 1958),

psychology, neurophysiology. For the original article on Lashley see DSB, vol. 8.

A major biographical treatment of Karl Lashley since the original DSB article is Nadine Weidman’s Constructing Scientific Psychology: Karl Lashley’s Mind-Brain Debates (1999). Weidman’s interpretation builds on earlier biographical work on Lashley by Darryl Bruce and Donald Dewsbury but also differs from it in noteworthy ways. Bruce has written two biographical articles on Lashley. One of them, “Lashley’s Shift from Bacteriology to Neuropsychology,

1910–1917, and the Influence of Jennings, Watson, and Franz” (1986), is focused on Lashley’s early career and traces the path that took him from bacteriology and genetics to his life’s work in neuropsychology. The other, “Integrations of Lashley” (1991), is a portrayal of Lashley as a pioneering psychologist. Dewsbury has examined a correspondence between Lashley and Lashley’s mentor and friend from the 1950s, John B. Watson, late in both men’s lives, in “Contributions to the History of Psychology XCIV: The Boys of Summer at the End of Summer” (1993).

While Bruce and Dewsbury portray Lashley as a pure, disinterested scientist whose work was devoid of social or political meaning, Weidman argues that Lashley’s neutral stance and avowed opposition to psychological theorizing were themselves political statements and that Lashley’s concept of brain function and his lifelong hereditarianism were correlated with his views on race and on the social order. Weidman’s biography emphasizes Lashley’s hereditarianism—his belief that intelligence and brain function were innate properties rather than influenced strongly by environment—and uses that emphasis to explain Lashley’s scientific stance, his opposition to certain traditions in psychology and biology, and his sociopolitical leanings.

According to this interpretation, Lashley’s doctoral work in genetics, done under the supervision of the biologist Herbert Spencer Jennings, encouraged Lashley’s interest in uncovering the biological and genetic bases of behavior. Lashley allied himself with the behaviorist Watson up to the mid-1920s, but he broke with behaviorism just as Watson was asserting the total shaping power of the environment on behavior. Lashley’s mature work involved the ablation, or destruction, of different areas of the rat’s cerebral cortex and the assessment of its effect on the rat’s behavior. He devised ingenious methods for testing the rats’ abilities to thread a maze, solve a puzzle box, and discriminate between different patterns, before and after ablation. The principles of equipotentiality and mass action that Lashley derived from his experimental work emphasized the dynamic functioning of the cortex and were opposed to the theory that memories, thoughts, or abilities were localized in discrete cells. This experimental work received thorough treatment in Brain Mechanisms and Intelligence (1929), the only book Lashley ever wrote. Lashley’s emphasis on dynamic functioning was also, according to Weidman, correlated with his innatist stance.

Lashley’s hereditarianism and interest in elucidating the biological bases of behavior brought him into conflict with two important traditions in twentieth-century American biology and psychology. His career was shaped by his debates with representatives of these two traditions, psychobiology and behaviorism. The first conflict pitted Lashley against his colleague at the University of Chicago, the psychobiologist and neurologist Charles Judson Her-rick. For Herrick, consciousness and free will were emergent properties of the nervous system that could never be fully explained by physics and chemistry. Lashley dismissed Herrick’s emergentism as mystical, arguing for the reduction of consciousness to the physico-chemical workings of the nervous system and against the notion of progress in evolution that underlay Herrick’s theory. Sharon Kingsland explores the assumptions of Herrick’s science in “A Humanistic Science: Charles Judson Herrick and the Struggle for Psychobiology at the University of Chicago” (1993). In Constructing Scientific Psychology (1999), Weidman develops Lashley’s side of the debate and examines his interactions with Herrick.

The second major debate of Lashley’s career was with Clark Hull, the neo-behaviorist psychologist at Yale University’s Institute of Human Relations in New Haven, Connecticut. In Hull, Lashley faced an opponent who was quite as opposed to Herrick’s emergentism as was Lashley himself. Both Hull and Lashley claimed the mantle of mechanistic, deterministic psychology but disagreed on what that meant. For Hull, behavior was the product of reflex connections between stimulus and response; how these connections were actually achieved in the brain mattered to him less than that behavioral outputs could be manipulated by changing the stimulating sensory inputs. Hull also believed that intelligent behavior could be simulated by a machine and spent some effort designing and building such “thinking machines.” According to Weidman, Lashley objected to such mechanical analogies for the mind and to Hull’s neo-behaviorist theory as well as to the emphasis on the environmental shaping of behavior that underlay Hull’s science.

Weidman’s interpretation of the Lashley-Hull debate in her book expands on her earlier article, “Mental Testing and Machine Intelligence: The Lashley-Hull Debate” (1994). Bruce criticizes Weidman’s interpretation of the debate in this article in “The Lashley-Hull Debate Revisited” (1998). Weidman’s response to Bruce (“A Response to Bruce”) and Bruce’s reply (“Lashley’s Rejection of Connectionism”)—in which he argues that a change in evidence from Lashley’s experiments underlay his break from behaviorism—can both be found in the May 1998 issue of History of Psychology.

Dewsbury compares Bruce’s and Weidman’s views of Lashley in his article “Constructing Representations of Karl Spencer Lashley.” There Dewsbury argues, in a critique of Weidman, that Lashley’s theories of dynamic cortical function and his emphasis on innate ability could be interpreted as correlated with his idiosyncratic and iconoclastic personality rather than with his sociopolitical views. Dewsbury’s article, Weidman’s response to it (“The Depoliticization of Karl Lashley”), and Dewsbury’s reply to her (“The Role of Evidence”) can all be found in the summer 2002 issue of the Journal of the History of the Behavioral Sciences.

Lashley ended his career as the director of the Yerkes Laboratories of Primate Biology in Orange Park, Florida. In keeping with his career-long interests, Lashley guided the work of the laboratories toward an investigation of the biological and ultimately genetic basis of intelligence and of sexual behavior in anthropoid apes.

SUPPLEMENTARY BIBLIOGRAPHY

Bruce, Darryl. “Lashley’s Shift from Bacteriology to Neuropsychology, 1910–1917, and the Influence of Jennings, Watson, and Franz.” Journal of the History of the Behavioral Sciences 22 (1986): 27–44.

———. “Integrations of Lashley.” In Portraits of Pioneers in Psychology, Vol. 1, edited by Gregory A. Kimble, Michael Wertheimer, and Charlotte White. Hillsdale, NJ: Erlbaum, 1991.

———. “The Lashley-Hull Debate Revisited.” History of Psychology 1, no. 1 (February 1998): 69–84.

———. “Lashley’s Rejection of Connectionism.” History of Psychology 1, no. 2 (May 1998): 160–164.

Dewsbury, Donald A. “Contributions to the History of Psychology XCIV: The Boys of Summer at the End of Summer: The Watson-Lashley Correspondence of the 1950s.” Psychological Reports 72 (1993): 263–269.

———. “Constructing Representations of Karl Spencer Lashley.” Journal of the History of the Behavioral Sciences 38, no. 3 (Summer 2002): 225–245.

———. “The Role of Evidence in Interpretations of the Scientific Work of Karl Lashley.” Journal of the History of the Behavioral Sciences 38, no. 3 (Summer 2002): 255–257.

———. Monkey Farm: A History of the Yerkes Laboratories of Primate Biology, Orange Park, Florida, 1930–1965. Lewisburg, PA: Bucknell University Press, 2006.

Kingsland, Sharon. “A Humanistic Science: Charles JudsonHerrick and the Struggle for Psychobiology at the University of Chicago.” Perspectives on Science 1 (1993): 445–477.

Weidman, Nadine M. “Mental Testing and Machine Intelligence: The Lashley-Hull Debate.” Journal of the History of the Behavioral Sciences 30 (April 1994): 162–180.

———. “Psychobiology, Progressivism, and the Anti-Progressive Tradition.” Journal of the History of Biology 29 (1996): 267–308.

———. “A Response to Bruce (1998) on the Lashley-Hull Debate.” History of Psychology 1, no. 2 (May 1998): 156–159.

———. Constructing Scientific Psychology: Karl Lashley’s Mind-Brain Debates. New York; Cambridge, UK: Cambridge University Press, 1999.

———. “The Depoliticization of Karl Lashley: A Response to Dewsbury.” Journal of the History of the Behavioral Sciences 38, no. 3 (Summer 2002): 247–253.

Nadine M. Weidman