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Thursday, December 2, 2010

INSTRUMENTAL LEARNING

THORNDIKE’S CATS EXPERIMENT
Pavlov was beginning work on classical conditioning in Russia, E.L. Thorndike, in the United States, was conducting a set of studies that initiated a different tradition in the laboratory study of basic learning mechanisms. Thorndike was interested in the notion of animal intelligence. Motivated by an interest in Darwinian evolutionary theory, comparative psychologists of the late nineteenth century had investigated whether non-human animals can show similar signs of intelligence to those shown by humans. Thorndike took this endeavour into the laboratory. In his best-known experiment, a cat was confined in a ‘puzzle box’ (figure 4.3). To escape from the box, the cat had to press a latch or pull a string. Cats proved able to solve this problem, taking less and less time to do so over a series of trials. Cats solved the problem not by a flash of insight but by a gradual process of trial and error. Nevertheless, here was a clear example of learning. Its characteristic feature was that the animal’s actions were critical (instrumental) in producing a certain outcome. In this respect, instrumental learning [instrumental learning the likelihood of a response is changed because the response yields a certain outcome (a reward or punishment) (also called operant conditioning)] is fundamentally different from classical conditioning, in which the animal’s response plays no role in determining the outcome. Subsequent researchers who took up the analysis of this form of learning include the Polish physiologist Konorski (1948), who called it Type II conditioning (as distinct from Pavlov’s Type I conditioning). Another investigator interested in this type of conditioning was Skinner (1938) in the United States, who named it operant conditioning (Pavlov’s version of learning being referred to as respondent conditioning). [respondent conditioning alternative name for classical conditioning] However termed, all agreed that its defining feature was a contingency between a preceding stimulus, a pattern of behaviour (or response) and a subsequent state of the environment (the effect or outcome).

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