Karl Lashley Research Paper

Karl Lashley was born in Davis, West Virginia on June 7, 1890. His parents were themselves successful—his father was variously a storekeeper, postmaster, banker, and mayor of Davis and his mother, energetic and intellectual with literary and artistic interests. Lashley grew up in Davis, except for a rather extraordinary trek; the family took to the gold rush in the Klondike in 1898–1899.

Lashley was an only child and acknowledged a great debt to his mother for nurturing his intellectual interests. He had learned to read well by the age of four. His mother taught in a country school until Karl was born but maintained a center for adult education in her home where women (and Karl) came for instruction in such subjects as civics, Greek poetry, and drama.

As a boy Karl read widely from the extensive family library but also displayed great interest in plant and animal life, wandering through the local fields and woods, collecting butterflies, snakes, frogs and snails, and keeping pet mice and raccoons.

Karl entered a private school at the age of four and later attended public schools in Davis, where he graduated from high school at the age of fourteen. He entered the University of West Virginia but did not qualify as a freshman because his high school was not accredited. He spent a preparatory year which he felt was wasted. He initially planned to study Latin but was instead assigned English as a major. To fill a vacancy in his schedule he enrolled in a course in Zoology taught by John Black Johnston, a neurologist and the only teacher of zoology at the university. This course and Johnston had a profound influence on Karl. He later wrote that ‘within a few weeks in his class I knew that I had found my life’s work.’

Lashley received his BA at West Virginia in 1910. He then entered the master’s degree program at the University of Pittsburgh as a teaching fellow. During his year there in biology, he attended a course in experimental psychology by Karl Dallenbach, a teaching fellow in psychology. To quote Dallenbach: ‘Lashley’s laboratory was on the floor above mine. Though he had never taken a course in psychology, he was permitted, because he was a fellow, to elect my laboratory course in experimental psychology. The class was small and we worked intimately together upon the various experiments. Lashley was intensely interested and was the outstanding student in the class—as one might expect being a graduate student in an undergraduate class, but he was more than a run-of-the-mine graduate student. He showed in that course the promise that he later fulfilled.’ (Beach 1961, p. 170).

The following summer Lashley worked at the Carnegie Laboratories at Cold Spring Harbor, where he conducted basic studies on a ciliate. A very distinguished zoologist at Johns Hopkins, H. S. Jennings, was so impressed with this work that he offered Lashley a fellowship. At Hopkins, Lashley worked with Jennings on paramecia and completed a Ph.D. thesis on inheritance in the asexual reproduction of Hydra (1914). Lashley took a minor in psychiatry with Adolf Meyer, a pioneering figure in biological psychiatry and another minor (in psychology) with John B. Watson. The influence of Watson on Lashley was profound.

In a letter written much later tOvernest Hilgard at Stanford, Lashley described taking a seminar with Watson in 1914. Watson called their attention in the seminar to the writings of Bechterev on conditioned reflexes, which they translated. ‘In the spring I served as an unpaid assistant and we constructed apparatus and did experiments, repeating a number of their experiments. Our whole program was then disrupted by the move to the lab in Meyer’s Clinic. There were no adequate animal quarters there. Watson started work with infants as the next best material available. I tagged along for awhile but disliked the babies and found me a rat lab in another building. We accumulated a considerable amount of experimental material on the conditioned reflex that was never published. Watson sought the basis of a systemic psychology and was not greatly concerned with the reaction itself.’ (Hilgard, personal communication, 1984).

The conditioned reflex thus came to form the basis of Watson’s behaviorism. Lashley, on the other hand, had become interested in the physiology of the reaction and the attempt to trace conditioned reflex paths through the central nervous system. At the end of his career, Lashley was reputed to have said that anyone who knows American psychology today (Circa 1958) knows that its value derives from biology and from Watson.

During the period at Hopkins, Lashley worked with Shepherd Ivory Franz at St. Elizabeth’s Hospital in Washington. Together, they developed a new approach to the study of brain mechanisms of learning and memory and published landmark papers on the effect of cortical lesions on learning in rats. From this time (1916) until 1929 Lashley systematically used the lesion method in the attempt to localize memory traces in the brain. Following Watson (and Pavlov), Lashley conceived of the brain as a massive reflex switchboard, with sequential chaining of input-output circuitries via the cerebral cortex as the basis of memory. This work culminated in his classic monograph Brain Mechanisms of Intelligence (1929). He was also President of the American Psychological Association that year. His presidential address, and his 1929 monograph, destroyed the switchboard reflexology theory of the brain function and learning as it existed at that time.

In complex mazes, rats were impaired in learning and memory in proportion to the degree of cerebral cortex destroyed, independent of locus. Lashley employed the terms ‘mass action’ and ‘equipotentiality’ more to describe his results than as a major theory. He did not deny localization of function in the neocortex; indeed, his work on visual discriminations strongly supported localization (see Lashley 1942). Using anatomical and physiological methods, he was perhaps the first to demonstrate the point-to-point projection from the lateral geniculate nucleus to the visual cortex. Rather, he argued that the neural substrate for higher order memorial functions, he often used the term ‘intelligence’, as in complex maze learning in rats, was widely distributed in the cerebral cortex. He did attempt to develop a theory of cortical field-like interference patterns as a mechanism to account for equipotentiality in perception and learning, but he found it wanting. ‘He remarked that he had destroyed all theories of behavior, including his own’ (Hebb 1959, p. 149). Lashley was perhaps the most formid- able critical thinker of his time, successfully demolishing all major theories of brain-behavior extant at the time, from Pavlov to the Gestalt psychologists, to his own views.

Lashley’s influence was such that the field concerned with brain substrates of learning and memory went into decline for a period of years. The studies by Lashley had critics. Walter Hunter, for example, noted that the more cortex destroyed, the more sensory areas are destroyed and the fewer sensory cues are available to the animal. Part of the problem is that maze learning is a very complex task; the notion that a simple localized engram or memory trace could serve to code the memory for a maze, seems unrealistic today. In fact, simple memories do appear to have engrams that are quite localized in the brain: conditioning of discrete responses like eyeblink in the cerebellum and conditioned fear in the amygdala. The brain structure most involved in spatial learning and memory is not the neocortex but rather the hippocampus, at least in rats. However, Lashley’s view is still held today in the sense that some cognitive scientists argue that complex memories are widely distributed in the brain. The jury is still out on this matter, no distributed memories having been found.

Near the end of his career, looking over his lifetime of research on memory, Lashley (1950) concluded that: ‘This series of experiments yielded a good bit of information about what and where the memory trace is not. It has discovered nothing directly of the real nature of the memory trace. I sometimes feel, in reviewing the evidence of the localization of the memory trace, that the necessary conclusion is that learning is just not possible. It is difficult to conceive of a mechanism that can satisfy the conditions set for it. Nevertheless, in spite of such evidence against it, learning sometimes does occur.’ (pp. 477–8).

Lashley’s positive contributions were extraordinary, including an insightful analysis of ‘instinctive’ behaviors, analysis of sexual behaviors, characterization of the patterns of thalamocortical projections, a rethinking of cortical cytoarchitectonics, etc. Lashley’s first professional position was as instructor of psychology at the University of Minnesota (1917). Robert Yerkes was to become the chair of the psychology department there and arranged Lashley’s hire. However, Yerkes became much involved in the organization of the National Research Council in Washington and did not move to Minnesota. Lashley left after one year, returning to Baltimore where he resumed his work with John Watson. Lashley returned to Minnesota in 1920, where he was promoted from instructor to full professor in three years. Lashley remained at Minnesota until 1926, when he moved to the University of Chicago.

In 1936 James B. Conant, then the new president of Harvard, appointed an ad hoc committee to find the best psychologist in the world. Lashley, then at the University of Chicago, was chosen and hired in 1937. He became Director of the Yerkes Laboratory of Primate Biology in Florida but maintained his Chair at Harvard, traveling to Cambridge once each year to give his two week graduate seminar. The roster of eminent psychologists and neuroscientists who worked with Lashley is without parallel.

Lashley was an extraordinary teacher, albeit most of his teaching was individual. He was of the view that those who need to be taught can’t learn and those who can learn don’t need to be taught. Following is a description of his teaching at Minnesota by a former student: ‘I saw Karl for the first time when I was taking a General Psychology course. An assembly lecture was given to all psychology classes once every two weeks, with different professors giving one lecture to about 200 students. Karl, tall, lean, sardonic held up a frog, made the muscles jump, grinned at us and talked informally in his rather precise voice. We learned more in 40 minutes from him than we had from the other eight professors and we all filed out of the hall wanting to know when we could take a course from this thin, splendid lecturer, with the pince-nez on a black string. We quickly learned that we couldn’t. He hated teaching formally and was available for only a few graduate students.’ (Beach 1961, p. 182).

Although Lashley is not widely recognized as one of the sources for the development of the current field of cognitive neuroscience, his extraordinary paper on the problem of serial order in behavior clearly anticipated this field (see Bruce 1994).

’This is the essential problem of serial order: the existence of generalized schemata of action which determine the sequence of specific acts, acts which in themselves or in their associations have no temporal valence’ (Lashley 1951, p. 122).

Lashley never wrote directly about the nature of consciousness. According to his student Roger Sperry (personal communication) he was interested in the problem of consciousness but refused to write about it, considering it to be perhaps something of an epiphenomenon. He did, however, speculate about the nature of mind: ‘Mind is a complex organization, held together by interaction processes and by time scales of memory, centered about the body image. It has no distinguishing features other than its organization … there is no logical or empirical reason for denying the possibility that the correlation (between mental and neural activities) may eventually show a complete identity of the two organizations’ (Lashley 1958, p. 542).

Lashley received essentially all the honors available to a psychologist: President of the American Psycho-logical Association; election to membership in the Society of Experimental Psychologists; British Psychological Association; Harvey Society; US National Academy of Sciences; Royal Society, London (Foreign Member); American Philosophical Society; American Academy of Arts and Sciences; granted the Howard Crosby Warren Medal by the Society of Experimental Psychologists for outstanding scientific contributions to psychology; the Daniel Girard Elliot Medal in Zoology by the National Academy of Sciences and the William Baly Medal in Physiology from the Royal College of Physicians. About the only honor he did not receive is the Nobel Prize, and many felt he should have done so. Sir Francis Walshe, a most distinguished neurologist, gave the following tribute: ‘… one of the most brilliant exponents of those problems that include psychology and physiology of the brain. He moved in this difficult territory with an experimental flair, an intellectual poise, and a competence he shared with few. His contributions to science were of a major order, and lesser men than he have been Nobel Prize men’ (Beach 1961, p. 191).

Frank Beach (1961) offered a favored tribute: ‘Eminent psychologist with no earned degree in psychology. Famous theorist who specialized in dis- proving theories, including his own. Inspiring teacher who described all teaching as useless’ (Beach 1961, p. 163).

Karl Lashley died in Poitiers, France on August 7, 1958.

Bibliography:

1. Beach F A 1961 A biographical memoir [of Karl Lashley]. Biographical Memoirs of the National Academy of Sciences 35: 162–204
2. Bruce D 1994 Lashley and the problem of serial order. American Psychologist 49: 93–103
3. Hebb D D 1959 Karl Spencer Lashley, 1890–1958. The American Journal of Psychology 72: 142–50
4. Lashley K S 1929 Brain Mechanisms and Intelligence. University of Chicago Press, Chicago
5. Lashley K S 1942 The problem of cerebral organization in vision. Biographical Symposia 7: 301–22
6. Lashley K S 1950 In search of the engram. Society of Experimental Biology, Symposium 4: 454–82
7. Lashley K S 1951 The problem of serial order in behavior. Cerebral Mechanisms in Behavior. John Wiley & Sons, New York, pp. 112–36
8. Lashley K S 1958 Cerebral organization and behavior. Proceedings of the Association for Research in Nervous and Mental Diseases 36: 1–18