Kenneth Spence

Introduction

Kenneth Wartinbee Spence (May 6, 1907 – January 12, 1967) was an American psychologist who, with Clark L. Hull, constructed the most influential neobehaviourist theory of learning of the 1940s and 1950s. Spence took Hull's highly formalised system of postulates and rebuilt parts of it, and he used the classical conditioning of the human eyeblink as a model preparation in which those postulates could be measured and tested. He made the University of Iowa into a major centre of theoretical psychology and trained an entire cohort of experimental psychologists; a 2002 survey placed him 62nd among the most-cited psychologists of the twentieth century, and in the last six years of his life he was the most-cited psychologist in the fourteen most influential journals of the field. His exacting style, in which theory was stated explicitly and then tested quantitatively on simple behaviours, set the standard for mid-century experimental psychology in the United States.

Early Life and Education

Spence was born in Chicago on May 6, 1907, the son of an electrical engineer. The family moved to Montreal in 1911 when his father was transferred by his employer, and Spence grew up there, attending West Hill High School in the district of Notre-Dame-de-Grâce, where he played basketball, tennis and track. A back injury sustained in a track competition at McGill University sent him to convalesce with his grandmother in La Crosse, Wisconsin; while there he enrolled at La Crosse Teachers College, majored in physical education, and met his first wife, Isabel Temte, with whom he had two children. He returned to McGill and changed his major to psychology, taking his bachelor's degree in 1929 — with the Prince of Wales Gold Medal in Mental Sciences — and his master's degree in 1930, along with the university's Governor General's Medal for Research.

From McGill he went to Yale University as a research assistant in the laboratory of the primatologist Robert M. Yerkes, and it was under Yerkes that he completed the dissertation for his 1933 doctorate, a study of visual acuity in chimpanzees. Spence is frequently described as Hull's doctoral student, and the description is only half right: his formal supervisor was Yerkes, but he took Hull's graduate course in experimental psychology, and while still a doctoral candidate he and Walter Shipley carried out an experimental test of one of Hull's deductions about the difficulty of blind alleys in maze learning. That collaboration grew into the intellectual partnership that gave the field its hyphenated label.

Academic and Professional Career

After his doctorate Spence held a National Research Council fellowship at the Yale Laboratories of Primate Biology in Orange Park, Florida, from 1933 to 1937, where he studied discrimination learning in chimpanzees and produced the work that shaped his later account of how animals learn to tell stimuli apart. In 1937 he accepted a one-year assistant professorship at the University of Virginia, and in 1938 he moved to the State University of Iowa. There he became a full professor and head of the psychology department in 1942, keeping both roles for more than two decades; he spent 26 years at Iowa in total, 22 of them as department head.

At Iowa, Spence, Kurt Lewin at the Child Welfare Research Station and the philosopher Gustav Bergmann made the department a centre for the attempt to turn psychology into an advanced natural science. Spence collaborated with Bergmann on logical positivism, which supplied the philosophical scaffolding for his own habit of stating theories as explicit postulate sets, and he established an eyelid-conditioning laboratory that became the empirical engine of his programme. He also contributed substantially to the preparation of Hull's Principles of Behavior, and Hull acknowledged the debt in the book's preface. In 1964 Spence left Iowa to head the psychology department at the University of Texas at Austin, expecting a long final phase of his career; he died of cancer in Austin on January 12, 1967, aged 59. In 1960 he married Janet Taylor, a former graduate student of his who had developed the Taylor Manifest Anxiety Scale and who became a distinguished psychologist in her own right; the two later founded the annual series The Psychology of Learning and Motivation.

Major Contributions to Psychology

The Hull-Spence Theory of Learning

Hull's system expressed behaviour potential as a joint function of habit strength (sHr), drive (D), incentive motivation (K) and various inhibitory factors, with the components multiplied together. Spence's contribution was both architectural and methodological. Architecturally, he summed drive and incentive rather than multiplying them, a technical revision with testable consequences: it predicted that raising motivational level would facilitate performance when the correct response was already the strongest tendency elicited by the stimulus, but would impair performance when competing tendencies were initially stronger. That prediction about the interaction of drive and habit was one of the few genuinely novel, checkable claims the neobehaviourist programme produced. Methodologically, Spence insisted that the theory's terms be tied to measurable operations, and he treated reinforcement as necessary for performance rather than for learning itself, a position that aligned him with the latent-learning results of Edward C. Tolman.

The Continuity Account of Discrimination Learning

In a two-choice discrimination task, rats typically perform at chance for an extended period and then improve abruptly. Karl Lashley and Ivo Krechevsky took the abrupt transition as evidence that animals test hypotheses discontinuously, discarding wrong ones and adopting the right one in a single step. Spence argued that the discontinuity is an artefact of the measure rather than of learning: what actually changes is continuous, with the excitatory tendency of the relevant stimulus dimension growing and the inhibitory tendency of the irrelevant dimension growing alongside it, until the difference crosses a threshold and becomes visible in choice behaviour. This "continuity" account framed a long-running dispute with Krechevsky and, later, with M. E. Bitterman, and it produced a substantial experimental literature on discrimination, transposition and reversal shifts.

Eyelid Conditioning as a Model System

Spence built his Iowa programme around classical conditioning of the human eyeblink, a response that is simple, precisely measurable and sensitive to motivational variables. The preparation let him test drive-theory predictions in human participants, connect conditioning performance to individual differences in anxiety measured by the Taylor scale, and study extinction and partial reinforcement in a system where the stimulus conditions could be controlled exactly. Students who trained in the laboratory described their degrees as being in "theoretical-experimental psychology," a phrase that captured Spence's insistence that experiment and theory were a single activity rather than two.

Theory Construction and Meta-Theory

Spence wrote influentially about how psychological theories should be built, arguing for explicit postulates, intervening variables and operational definitions, and treating behaviourism as a method as much as a doctrine. Papers such as "The Nature of Theory Construction in Contemporary Psychology" (1944) and "The Postulates and Methods of Behaviorism" (1948) were widely read and shaped how a generation of American psychologists thought about the relationship between data and theory.

Major Publications

"The Nature of Discrimination Learning in Animals," Psychological Review (1936)
"The Differential Response in Animals to Stimuli Varying Within a Single Dimension," Psychological Review (1937)
"Continuous Versus Non-continuous Interpretations of Discrimination Learning," Psychological Review (1940)
"The Nature of Theory Construction in Contemporary Psychology," Psychological Review (1944)
"Theoretical Interpretations of Learning," in S. S. Stevens (ed.), Handbook of Experimental Psychology (1951)
Behavior Theory and Conditioning (1956)
Behavior Theory and Learning: Selected Papers (1960)

The 1951 item is a chapter in an edited handbook rather than a book of its own, and it is often miscited with a 1942 date; Behavior Theory and Conditioning originated as Spence's 1955 Silliman Lectures at Yale.

Impact and Legacy

Spence directed 75 doctoral dissertations, and his students went on to faculty positions in every major psychology department in the United States. He was elected to the National Academy of Sciences, received the Howard Crosby Warren Medal from the Society of Experimental Psychologists in 1953, and in 1956 became the first recipient of the American Psychological Association's Award for Distinguished Scientific Contributions. The formal style he championed survived its theoretical content: the descendants of the Hull-Spence programme include Allan Wagner's associative models of conditioning and the broader tradition of quantitative learning theory that runs through Rescorla-Wagner style accounts.

The theory itself did not survive. It is worth being precise about why, because the criticisms are structural rather than incidental. First, habit strength was inferred from the same performance it was invoked to explain, so in the absence of an independent measure the central postulates were difficult to falsify; the same charge was levelled at Hull's system as a whole and is the standard objection to intervening-variable theories. Second, Spence's own revision of the drive and incentive terms made the model less specific, not more: summing where Hull multiplied removed some of the distinctive predictions and, with them, some of the theory's exposure to disconfirmation. Third, the continuity dispute largely went against him over time, as hypothesis-based and learning-set accounts gained ground and as transposition and reversal-shift studies were read as evidence for dimensional rather than incremental learning. Fourth, the surrounding intellectual ecology changed: mathematical learning theory of the Estes and Richard C. Atkinson kind, and then the cognitive revolution, displaced the Hullian programme, and by the 1970s the system was chiefly of historical interest. Reviewers of mid-century behaviourism have made the further point that the drive construct absorbed motivational and emotional phenomena that later proved to need separate treatment, and that the eyelid preparation, for all its precision, was a narrow base from which to generalise to human learning. That criticism is directed at the research programme rather than at Spence as a theorist, and even his critics generally concede that the measurement discipline he imposed on the field outlasted the postulates it was built to test.

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References

Spence, K. W. (1956). Behavior Theory and Conditioning. Yale University Press.