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Summary Article: Hull, Clark L. (1884–1952)
from The Corsini Encyclopedia of Psychology and Behavioral Science

Clark L. Hull’s most important contribution to psychology lies in his theory of learning, considered one of the most important learning theories of the twentieth century. He received his PhD in 1918 at the University of Wisconsin. Early in his career he was interested in the field of aptitude testing, an area he abandoned because he did not see much future in it. He then turned to the field of hypnosis and suggestibility. In 1929 he accepted an appointment as research professor at Yale University, a post he held until his retirement.

For most of his career Hull devoted himself to the development of a theory of learning along with experimental research to support it. In 1940, with a number of colleagues he published A Mathematico-Deductive Theory of Rote Learning. This was considered a masterpiece in theory construction, but it was so complicated that most psychologists failed to understand it. In 1943, he published the first complete statement of his theory of learning, Principles of Behavior, of which revisions followed in 1951 and 1952.

Hull’s theory was basically an S-R (stimulus-response) theory, but an expanded and complicated one, and it reflected some influences from the behavioristic ideas of John Watson. Hull was also influenced by Ivan Pavlov’s work on the conditioned reflex, which he considered to be a simple form of learning on which more complex kinds of learning could be built.

Like B. F. Skinner, Hull stressed the importance of reinforcement if learning was to take place. Reinforcement was successful because it resulted in the reduction of drives. Thus, the concept of drives and their reduction became an important aspect of Hull’s theory. He considered the environmental influences on the organism as well: these were input, while the responses the organism made were output.

The formulation of hypothetico-deductive theory of learning involved a series of postulates that should eventually be tested by experimentation. The final formulation of the theory consisted of 18 postulates and 12 corollaries, stated in both mathematical and verbal forms. Hull’s theory also included intervening variables, constructs that are assumed but never really subject to direct experimental verification.

Hull’s theory was systematic and generated a great deal of research. He insisted on well-controlled experiments and on the quantification of the resulting data. His theory was expanded and modified by Kenneth Spence and was widely taught and studied as the Hull-Spence theory of learning.

Suggested Reading
  • Hull, C. L. (1952). Principles of behavior: An introduction to behavior theory. New York: Appleton. .
    Wheaton, IL
    Copyright © 2010 by John Wiley & Sons, Inc. All rights reserved.

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