Examine the Influences of Gestalt Psychology on Modern Cognitive Psychology
CANADIAN JOURNAL OF PSYCHOLOGY, 1983,37(1), 4-7
Neuropsychology: Retrospect and Prospect
D.O. Hebb Dalhousie University
ABSTRACT The author presents a brief history of neuropsychology and ends with suggestions for future development.
RESUME L'auteur presente un bref historique de la neuropsychologie et ter- mine avec des suggestions de developpement futur.
This is a brief look at the past, to see how neuropsychology got where it has, and some biased ideas about what it must be if it is to continue its progress. So that the bias may be quite clear, here is a summary statement: In my mind psychology is one, not a loose assemblage of separate disci- plines; neuropsychology is fundamental to it, but not a separate area of re- search to be pursued in isolation from other modes of psychology. It fre- quently uses physiological methods, but remains distinct from physiology since its direct concern is not with synapse or corpus callosum or cortex, but with the behaviour of the whole animal.
K.S. Lashley was the great exemplar of neuropsychology and practically its founder. It really began with him, even if the methods available to him now look primitive, and even if others had already collected a considerable body of relevant data, from clinical cases and from physiology and histo- logy. He was the first to combine behavioural sophistication in experiments, with neurological sophistication. Incidentally, he also began "neuropsycho- logy" in another sense; I have had a number of queries about the origin of the word, which as far as I can discover first appeared in Lashley's paper of 1937, "Functional determinants of cerebral localization," publication of a talk given the previous year to psychiatrists and neurologists in Boston. Working at first with Franz, Lashley developed what was then a new kind of extirpation experiment in the analysis of learning, retention, and visual per- ception. With the smooth-brained rat as the subject he could quantify corti- cal destruction, and he set standards of postmortem reconstruction of the experimental lesion that have influenced all subsequent work.
Paradoxically, however, Lashley's work was so effective that it helped cause the near disappearance of neuropsychology during the second quar- ter of this century, 1925-1950. From Wundt and James and Thorndike onward it was accepted that psychology is directly concerned with the brain. Wundt said his was physiological psychology, James talked about habits as pathways worn in the brain, Thorndike's early work was explicit about connections in the nervous system. Such ideas clearly had value in the first stages of learning how to think about the neural basis of cognition and behaviour, but they were only a beginning; when they began to be
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taken for established fact, there was trouble. In a remarkable series of papers in the 10-year period from 1921 to 1930, Lashley provided experi- mental evidence to show (1) that when a habit becomes automatized, its locus does not move from cortex to lower structures but is still cortical ("cortical" and "conscious" had become interchangeable); (2) that localiza- tion in motor cortex is variable, and this area is not prerequisite to motor response; (3) that there is none but the grossest localization of habits in the cortex; (4) that synaptic resistance is not lowered by passage of the im- pulse; (5) that a rat's mastery of the maze is much more than a series of conditioned responses. Never mind that some of these papers had flaws. The flaws were not evident in the current state of knowledge, and the work had a devastating impact on current ideas. Simple-minded explanations of brain-behaviour relations were no longer acceptable. In fact, neuropsycho- logical theory disappeared.
The field was taken over by Tolman with black-box theory; by Skinner, opposed to any use of theory; and by Hull, personally inclined toward a neu- rological formulation of his theory but dissuaded by colleagues. When I was preparing Lashley's necrology for the American Journal of Psychology in 1958, I wrote to Tolman and Skinner to ask whether they had been in- fluenced by Lashley's results in their avoidance of any reference to the ner- vous system. Both denied any such influence, but a certain skepticism may be in order here. If, as it seems, the whole climate had changed, anyone's thinking might be influenced without one being aware of the cause of the change. Certainly Lashley's experimental critique had made it hard for anyone to argue the value of neurologizing. In fact, the excitement surroun- ding our work in the Donner Building of McGill University in the early fifties was partly because we were restoring something, after a long absence, that is a natural part of psychology.
If Lashley was the theorist who destroyed theory, Wilder Penfield at the Montreal Neurological Institute was a principal occasion for its revival with- out ever having had such a thought. He was not psychologically sophistica- ted to begin with but his surgical results led him eventually to an interest in consciousness, will, memory, and language. This was still not at a level that would have been approved of in a first-year course in psychology, but it was of course only a side-line for Penfield; he was fully engaged in making a revolution in neurology and neurosurgery.
The revolution got under way about 1936, when it appeared that the pre- frontal lobe could be removed with no obvious adverse effect. This was at a time when it was generally thought that the frontal lobe was the seat of all that is good and great about human beings. I was a Fellow of the Institute for two years, 1937-1939, and the principal result of my research was that I could find no defect of intelligence-test performance after removals from the prefrontal lobe. (I knew of course that there must be other defects, which Brenda Milner demonstrated much later.) During my stay at the MNI,
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Herbert Jasper came to show what the EEG could do in diagnosis, and I wish to record that I was present at and observed the first clinical electro- corticogram which Jasper recorded direct from the patient's exposed cortex. The new electronic methods opened up new possibilities, and when I returned to the Department of Psychology at McGill eight years later I found that epileptic foci were being detected in the temporal lobe in a way that had not been possible before. The temporal lobe now became the centre of attention for many.
About 1948, McGill's Donner Building was completed. Half of its third floor was given to Psychology for an animal lab only a couple of hundred yards from the MNI. Now began that period of excitement to which I have already referred. I do not think I exaggerate in saying that it was here, jointly in the Donner Building and the MNI, that the renaissance of neuropsy- chology began. The revival no doubt was ready to occur and would have oc- curred anyway before long, not only because it was time for it but also be- cause of new and stimulating developments in physiology, such as Moruzzi and Magoun's discovery of the ascending reticular activating system, or Brock, Coombs, and Eccles's work with intracellular recording and their de- monstration of inhibition. But we were the precipitant, and clearly more than a precipitant.
Some of this work was obviously neuropsychology — Brenda Milner, for example, doing a thesis on the temporal lobe at the MNI, Peter Milner inte- rested in implanting electrodes in the rat brain for subcortical stimulation, and developing the necessary technique. (This broadening of our research capability, by the way, was entirely due to him.) But other work, also exci- ting, was done with intact animals — rodent, canine, or human — and this was neuropsychology too. It is important I think to recognize that neuropsy- chology is not just a question of method. The essential is the purpose of the work and the kind of ideas that underlie it. The purpose in neuropsychology is to increase both knowledge and understanding of the cerebral mecha- nisms controlling behaviour. Obviously, this comprises Olds and Milner's discovery of the pleasure centres or reward centres in the rat brain; but it also comprises Hymovitch's demonstration that adult intelligence depends on the sensory environment of infancy and that this effect may be largely perceptual learning, or the demonstration by Heron, Bexton, Scott, and Doane that the adult continues to depend on the same sensory exposure to maintain normal functions — the so-called sensory deprivation experiment. Both experiments were designed to provide information about brain func- tion, but neither used surgical methods.
Also, finally, these two experiments have something to suggest concer- ning the future of neuropsychology and neuropsychological research. Each arose from a set of neurological ideas, the theory of cell-assemblies, but the theory had to be tested with intact subjects. Is it not inevitable that progress in understanding the operation of the brain as a whole will increa-
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singly follow a pattern: first, a theoretical neurological formulation implying that some previously unknown psychological process exists, or that a new organization of a known process is required; such process must then be looked for in normal subjects, which means also that the study of normal subjects will be a natural and necessary accompaniment of advances in neuropsychological research. The psychological developments in question will be subtle, departing more and more from common sense notions as these advances continue. Dealing with them will call for psychological sophistication, and the neuropsychologist of the future must be psychologist as much as neurologist. I have been told that neuropsychology will be so complex that it will have to split off from psychology proper. If these consid- erations are sound, that will hardly occur. Ultimately, the complexities of psychology and the complexities of neurology are the same complexities. They will not be handled any better by being treated separately in different compartments. Moreover, those complexities are such that the part played by theory in their resolution will be crucial; the natural preference of the neu- ropsychologist for descriptive fact will hardly be enough. The omens are that the neuropsychology of the future must be more substantially supported by a theoretical framework.