| Clark Leonard Hull | |
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Clark Leonard Hull
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| Born | 24 May 1884 Akron, New York |
| Died | 10 May 1952 New Haven, Connecticut |
| Nationality | American |
| Fields | psychologist |
Clark Leonard Hull (1884 - 1952) was an influential American psychologist who sought to explain learning and motivation by scientific laws of behavior. Born in Akron, New York, Hull obtained bachelor's and master's degrees from the University of Michigan, and in 1918 a PhD from the University of Wisconsin–Madison, where he also taught from 1916 to 1929. His doctoral research on "Quantitative Aspects of the Evolution of Concepts" was published in Psychological Monographs.
Hull conducted research demonstrating that his theories could predict and control behavior. His most significant works were the Mathematico-Deductive Theory of Rote Learning (1940), and Principles of Behavior (1943), which established his analysis of animal learning and conditioning as the dominant learning theory of its time. Hull is known for his debates with Edward C. Tolman. He is also known for his work in drive theory. Hull’s model is couched in biological terms: Organisms suffer deprivation. Deprivation creates needs. Needs activate drives. Drives activate behavior. Behavior is goal directed. Achieving the goal has survival value.
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Hull's formula for determining motivation, was sEr = sHr * D
sEr = excitatory potential (likelihood that the organism would produce response r to stimulus s),
sHr = habit strength (derived from previous conditioning trials),
D = drive strength (determined by, e.g., the hours of deprivation of food, water, etc.ariety of other factors were gradually added to the formula to account for results not captured by this simple function. Eventually the formula became:
sEr = V x D x K x J x sHr - sIr - Ir - sOr - sLr
where V is the stim
Hull is often credited with having begun the modern study of hypnosis.
His work Hypnosis and Suggestibility (1933) was a rigorous study of the phenomenon, using statistical and experimental analysis. Hull's studies emphatically demonstrated once and for all that hypnosis had no connection with sleep ("hypnosis is not sleep, … it has no special relationship to sleep, and the whole concept of sleep when applied to hypnosis obscures the situation").
The main result of Hull's study was to examine the veracity of the apparently extravagant claims of hypnotists, especially regarding extraordinary improvements in cognition or the senses under hypnosis. Hull's experiments showed the reality of some classical phenomena such as mentally induced pain reduction and apparent inhibition of memory recall.
However, Clark's work made clear that these effects could be achieved without hypnosis being seen as a distinct state, but rather as a result of suggestion and motivation, which was a forerunner of the behavioural approach to hypnosis. Similarly, moderate increases in certain physical capacities and changes to the threshold of sensory stimulation could be induced psychologically; attenuation effects could be especially dramatic. Hull is famous for his signature hypnotic induction in which he would look at someone straight in the eyes until they were induced.
Hull received the Warren Medal in 1945 from the Society of Experimental Psychologists. In 1929, he moved to Yale and stayed there until his death. He died on May 10, 1952, in New Haven, Connecticut.