Hunter, Walter S. (1889-1954)

views updated

HUNTER, WALTER S. (1889-1954)

Scientists studying learning and memory know Walter Samuel Hunter best for his analytical application of a device for assessing short-term retention, the delayed-response task. But his contributions to psychology were much more broad, and deep, than that. He was an influential and moderating force in the behaviorist movement; his thoughts and experiments included topics that remain issues of mainstream interest, such as the nature of an animal's representation for memory, consciousness, and genetic influences on intellectual achievement; and he was a significant applied psychologist with the military.

When Hunter was born, in 1889, it had been about a century since his Scotch-Irish ancestors had come to the United States. Born in Decatur, Illinois, within a year of the births of U.S. president Dwight D. Eisenhower (1953 to 1961), French soldier Charles de Gaulle, German dictator Adolf Hitler, English motion-picture actor Charles Chaplin, and English poet and critic T. S. Eliot, Hunter spent his early adolescence working on his father's farm near Fort Worth, Texas. His intellectual interests emerged early. In the first stages of his adolescence he purchased and read English naturalist Charles Darwin's groundbreaking Origin of Species and Descent of Man, and by age fifteen he had developed an active interest in a career in electrical engineering (Hunt, 1956). He attended Polytechnic College at Fort Worth with this objective in mind, but psychology attracted his attention through his reading of American psychologist and philosopher William James's textbooks, and he transferred to the University of Texas in 1908 to study this field (Hunt, 1956).

After graduating from the University of Texas in 1910, he pursued his graduate work at the University of Chicago. Within only two years he completed his doctorate and returned as an instructor to the University of Texas. But these two years at Chicago must have been a concentrated experience indeed, in view of two particularly substantial outcomes. First, his thinking as a scientist was shaped by two of his professors, James Angell and Harvey Carr, who were among the leading functionalists of the day. Their influence undoubtedly helped form Hunter's favorable view of behaviorism, which had close links to functionalism (an orientation that emphasized the relationships between environmental or task variables and learning, rather than theories of how hypothetical processes determine the occurrence of learning). In addition, Angell had directed the Ph.D. dissertation of John Watson at the University of Chicago a few years earlier. He undoubtedly maintained sufficient contact with Watson to transmit the latter's ideas to his own students. It is likely that in this way, Hunter was exposed early to the notions set forth by Watson in his Psychological Review paper mapping out the elements of behaviorism just one year after Hunter received his Ph.D.

Undeterred by a teaching load of four courses per semester, Hunter was productive in his research at the University of Texas, and after four years was appointed professor and head of the department of psychology at the University of Kansas (at age twenty-seven). Soon afterward, World War I required that Hunter work in the military service. As a psychological examiner he helped illustrate the predictive value of simply administered psychological tests, and in World War II he served as one of the military's leading administrators of such testing. In 1925 Hunter became the first G. Stanley Hall Professor of Genetic Psychology at Clark, and in 1936 he was named head of the department at Brown University, where he remained until his death in 1954 (Carmichael, 1954). Hunter worked influentially in the editing of several journals (Psychological Bulletin, Comparative Psychology Monographs, Behavior Monographs, and Journal of Animal Behavior), and he created Psychological Abstracts and edited it for twenty years. His several and diverse honors included membership in the National Research Council and the National Academy of Sciences, posts as president of several professional research societies, including the American Psychological Association, and receipt of the U.S. President's Medal for Merit for his service as chairman of the Applied Psychology Panel of the National Defense Research Council during World War II (Schlosberg, 1954).

Hunter's scientific contributions are equally impressive and diverse, including his study of visual afterimages, auditory discriminations, and issues of social psychology, consciousness, and thinking, but his most lasting contributions dealt with the topic that pervaded his writing in all other respects: memory. This is despite the fact that Hunter himself assiduously avoided reference to "memories" or a "memory process" in animals. To describe how a horse seemed to remember the route home, Hunter preferred instead the concept of "sensory recognition," which, he felt, avoided attributing ideation to animals.

Hunter's Ph.D. thesis was intended to test the animal's behavior in the absence of an eliciting stimulus, the sort of circumstance that might be thought to require a memory system of some sort. He chose a test of retention that had been tried out by two of Carr's students, Haugh and Reed. Whatever its origin, Hunter adapted the delayed-response task in a fashion sufficiently convincing to persuade others to use it as the dominant task for short-term retention over the next fifty years, until delayed matching-to-sample came to be more effectively applied through the use of computers.

In his first version of this task Hunter trained hungry animals initially to obtain food by entering the lighted door of three possible doors (in a later version, no light was used and only the location of the door indicated the reward site). After the animal had perfected this discrimination, Hunter began trials in which the light was shown in the same way but turned off before the animal was allowed to choose a door. For the animal to reach this point required hundreds of training trials. Yet, because responding was permitted only in the absence of the stimulus, at specified intervals after taking it away, reliable correct responding hardly could be caused by sensory recognition; there were no sensory events to be recognized. So long as he could discount "overt orienting attitudes" of the sort that a hunting dog might use when indicating the location of a bird in the field, accurate choice could apparently be attributed to control by an internal representational response, or some other form of ideation. Hunter reasoned that the efficiency of ideation could be compared across various species of animals or even between animals and humans by increasing the interval between the offset of the light and the opportunity to respond.

Hunter estimated the longest retention interval that each of his subjects could tolerate before retention no longer was significant. For rats he estimated this to be about ten seconds, for raccoons twenty-five seconds, for dogs five minutes, for his thirteen-month-old daughter Thayer about twenty-four seconds, for two-and-a-half-year old children fifty seconds, and for a six-year-old child twenty minutes. Hunter judged that the rats were solving the problem by using the overt orienting attitudes of the pointer, but this did not seem necessary for the raccoons and children, so Hunter entertained the possibility that "sensory thought" might be involved for these subjects. He supposed that the critical stimulus—the position of the light or the location of the exit holding the reward—might be represented within the animal as an intraorganic cue, probably of a kinesthetic nature.

Hunter's research stimulated a number of studies by other scientists directed at one of two issues of phylogeny: which animals can perform such a delayed response task without the use of physical orientation and thus reveal a capacity for internal ideation of the "sensory thought" type suggested by Hunter; and how animals are ordered phylogenetically in terms of their capacity for such ideation, which was presumed to be tapped by the degree to which correct responding occurred after a long delay interval. Hunter later argued that correct performance of the double alternation task also could reveal a capacity for ideation. Hunter made substantial contributions to psychology throughout his forty-two years in the field. His ideas in a variety of areas within psychology were influential, but it can be argued that none of his subsequent experiments had the impact of his Ph.D. thesis.

Some intriguing paradoxes of Hunter's career have been described by Hunt (1956) and are paraphrased here. Despite Hunter's success in avoiding serving in university administration, for which he was frequently sought, he was obviously a successful administrator, as indicated by the strength of the department he built at Brown and his work in the military. Despite his sympathy with and support of behaviorism, some of his most important research seemed more clearly understandable in terms of the use of symbolic processes by animals. Although he was one of the most influential experimental psychologists of the first half of the twentieth century, he spent the last ten years of his life focusing on psychology's applications. Finally, Hunt notes two paradoxes of Hunter's personal life: Despite a high rate of professional productivity, Hunter always seemed relaxed and with time to spare; and, despite his emphasis on being impersonal and objective as a scientist, he was warm in his relationships with others.

Hunter's primary contribution to the field of learning and memory was to implement two tasks, the delayed response and the double alternation task, which provided a metric for discussing animal memory in an objective fashion and a forum for considering the use of representation in memory by animals.