LEARNING THEORY

any of the proposals put forth to explain changes in behaviour produced by practice, as opposed to other factors, e.g., physiological development. A common goal in defining any psychological concept is a statement that corresponds to common usage. Acceptance of that aim, however, entails some peril. It implicitly assumes that common language categorizes in scientifically meaningful ways; that the word learning, for example, corresponds to a definite psychological process. However, there appears to be good reason to doubt the validity of this assumption. The phenomena of learning are so varied and diverse that their inclusion in a single category may not be warranted. Recognizing this danger (and the corollary that no definition of learning is likely to be totally satisfactory) a definition proposed in 1961 by G.A. Kimble may be considered representative: Learning is a relatively permanent change in a behavioral potentiality that occurs as a result of reinforced practice. Although the definition is useful, it still leaves problems. The definition may be helpful by indicating that the change need not be an improvement; addictions and prejudices are learned as well as high-level skills and useful knowledge. The phrase relatively permanent serves to exclude temporary behavioral changes that may depend on such factors as fatigue, the effects of drugs, or alterations in motives. The word potentiality covers effects that do not appear at once; one might learn about tourniquets by reading a first-aid manual and put the information to use later. To say that learning occurs as a result of practice excludes the effects of physiological development, aging, and brain damage. The stipulation that practice must be reinforced serves to distinguish learning from the opposed loss of unreinforced habits. Reinforcement objectively refers to any conditionoften reward or punishmentthat may promote learning. However, the definition raises difficulties. How permanent is relatively permanent? Suppose one looks up an address, writes it on an envelope, but five minutes later has to look it up again to be sure it is correct. Does this qualify as relatively permanent? While commonly accepted as learning, it seems to violate the definition. What exactly is the result that occurs with practice? Is it a change in the nervous system? Is it a matter of providing stimuli that can evoke responses they previously would not? Does it mean developing associations, gaining insights, or gaining new perspective? Such questions serve to distinguish Kimble's descriptive definition from theoretical attempts to define learning by identifying the nature of its underlying process. These may be neurophysiological, perceptual, or associationistic; they begin to delineate theoretical issues and to identify the bases for and manifestations of learning. (The processes of perceptual learning are treated in the article perception: Perceptual learning.) Additional reading John F. Hall, The Psychology of Learning (1966), provides a comprehensive account of the empirical data that theories of learning are designed to integrate. Ernest R. Hilgard and Gordon H. Bower, Theories of Learning, 5th ed. (1981), is the standard reference on this subject. Ernest R. Hilgard and Donald G. Marquis, Hilgard and Marquis' Conditioning and Learning, 2nd ed. rev. by Gregory A. Kimble (1961), describes theoretical issues as they apply to simple learning. The separate articles reproduced in Gregory A. Kimble (ed.), Foundations of Conditioning and Learning (1967), develop some of these arguments in more detail and also present synopses of the theoretical positions of Hull, Guthrie, and Tolman. Gregory A. Kimble, Norman Garmezy, and Edward Zigler, Principles of Psychology, 6th ed. (1984), is a general textbook that covers several theoretical issues and should be particularly useful on the topics of memory and retrieval. William Bechtel and Adele Abrahamsen, Connectionism and the Mind: An Introduction to Parallel Processing in Networks (1991), gives an overview of connectionist theory and higher-level cognitive processing. David E. Rumelhart et al., Parallel Distributed Processing: Explorations in the Microstructure of Cognition, 2 vol. (1986), is a landmark collection of articles on the connectionist theory of learning. Philip Johnson-Laird, The Computer and the Mind, 2nd rev. ed. (1993), provides an easy introduction to cognitive science. Gregory A. Kimble The Editors of the Encyclopdia Britannica