Hulls Learning Theory

American psychologist Clark Leonard Hull (1884-1952) formulated a hypothetico- deductive, behavioristic, reductive, mechanistic, and Darwinian/adaptive learning theory that uses habit as its core concept, along with a number of intermediary (mediational theories) theoretical constructs called intervening variables. The notion of intervening variables was first described by the American psychologist Edward C. Tolman (1886-1959) in 1938 [cf., hypothetical construct - a conjectured process, event, or entity that contains "surplus meanings" and is not observed directly but is used to explain an observable and measurable phenomenon; in 1948, the American psychologists Kenneth MacCorquodale (1919-1985) and Paul E. Meehl (1920-2003) made a distinction between hypothetical constructs and intervening variables where the latter refer to variables whose values are determined by a specified manipulation of independent variables without any hypotheses about the existence of unobserved entities or processes]. In Hull's system, it is assumed that a given psychological state usually involves multiple causes and multiple effects, and this necessitates the postulation of various intervening variables that mediate between observable cause and observable effect events within the organism. For example, Hull describes the intervening variable of "thirst" as mediating the input variable of "hours of water deprivation" and the output variable of "amount of water drunk." In his theory, Hull postulates about eight intervening variables (such as "habit" or "thirst") and describes their causal input variables. Several intervening variables are combined to determine the organism's final behavior observed in problem-solving and conditioning tasks. Among Hull's other theoretical concepts and constructions are habit strength, drive level, positive associative response strength, negative/inhibitory response strength, conditioned inhibition, reaction potential, net response strength, incentive motivation, drive stimuli, fatigue, general drive pool, evoking-stimulus goodness, anticipatory goal responses, gradient of reinforcement, habit-family hierarchy, and fractional anticipatory goal reaction (cf., Hull's multiple response principle - states that an organism will react to a new/novel situation with a number of potential responses already within its behavioral repertoire). In his ambitious behavior theory and program of experimentation, Hull developed sequences of calcula-tional stages, equations, and mathematical derivations that describe both the acquisition and extinction of conditioned responses that, in the abstract, are similar to Ivan Pavlov's notions of behavior as being determined by the subtraction of internal inhibition from excitation and, also, to E. R. Guthrie's ideas of the competition among conditioned responses vis-à-vis the interfering movements evoked by the conditioned stimulus. Hull went beyond E. L. Thorndike's law of effect and hypothesized that all primary/biological reinforcers serve to reduce their corresponding drive/need; he concluded that any reduction of a drive may act as a reinforcing event. In his factor theory of learning, Hull characterizes the complex phenomena of learning in terms of two factors: classical and operant/instrumental conditioning principles that are necessary to explain learning (cf., factor theory - based on the work of Sir Francis Galton, any school or theory that analyzes behavioral phenomena in terms of different aspects or factors, and also describes theories based on two separately identifiable processes; for example, physiological and cognitive processes). Criticisms against Hull's theory are that it does not have a tractable mathematical system, it has too many parameters to be measured and too weak a measurement theory to get leverage on the quantitative details of his experimental data, and its mathematical derivations are suspect in detail where ad hoc rules are often invented to handle special problems arising in each derivation. On the positive side, Hull's quantitative system and program - which arguably was the most influential of the learning theories between 1930 and 1955 - set the stage for later development in the area of mathematical learning theory. Hull also influenced profoundly a number of his students (the "neo-Hullians") and other prominent re-searchers and writers in learning psychology, such as N. E. Miller, O. H. Mowrer, K. Spence, A. Amsel, and F. Logan. See also AMSEL'S HYPOTHESIS AND THEORY; EFFECT, LAW OF; GALTON'S LAWS; GUTHRIE'S THEORY OF BEHAVIOR; LEARNING THEORIES/LAWS; LOGAN'S MICROMOLAR THEORY; MOWRER'S THEORY; PAV-LOVIAN CONDITIONING PRINCIPLES/LAWS/THEORIES; SPEN-CE'S THEORY; TOLMAN'S THEORY. REFERENCES

Hull, C. L. (1932). The goal-gradient hypothesis and maze learning. Psychological Review, 39, 25-43. Hull, C. L. (1938). The goal-gradient hypothesis applied to some "field-force" problems in the behavior of young children. Psychological Review, 45, 271-299.

Tolman, E. C. (1938). The determiners of behavior at a choice point. Psychological Review, 45, 1-41.

Hull, C. L. (1943). Principles of behavior. New York: Appleton-Century-Cro-fts.

On a distinction between hypothetical constructs and intervening variables. Psychological Review, 55, 95107.

Hull, C. L. (1951). Essentials of behavior. New Haven, CT: Yale University Press.

Hull, C. L. (1952). A behavior system: An introduction to behavior theory concerning the individual organism. New Haven, CT: Yale University Press.

Seward, J. (1954). Hull's system of behavior: An evaluation. Psychological Review, 61, 145-159. Cotton, J. (1955). On making predictions from Hull's theory. Psychological Review, 62, 303-314.

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  • abbondanzio bianchi
    How are input variables and intervening variables different in hull theory?
    4 months ago

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