The effect of prior experience on a current learning task is of the utmost relevance to theories of learning. In special cases, prior experience may even prevent subsequent learning. These cases can generally be thought of as instances of the blocking phenomenon (e.g., Kamin, 1969; Wagner, Logan, Haberlandt, and Price, 1968). Specifically, if a stimulus A is paired with a reinforcer so that a response comes under the control of that stimulus, then when a novel stimulus B is simultaneously compounded with A and also paired with the reinforcer, stimulus B does not acquire control over the response, as measured by presentation of B alone in extinction. Stimulus A is said to "block" the establishment of stimulus control by B.

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Thesis (Ph.D.)--Boston University. / This study used the procedures of classical conditioning to investigate the possibility of producing asthmatic bronchospasm as a conditioned response. In order to carry out this study equipment was developed which permitted the experimental operations to be carried out while disguising the purpose of the experiment from the subjects. In the experiment, bronchospasm, induced by inhaled acetyl beta methacholine chloride, and shown to be highly similar to the condition of the lungs in asthma, was paired with auditory or visual stimuli. Similarly, Isuprel-induced relief of bronchospasm was paired with another exteroceptive stimulus in an attempt to condition the end of the attack. Subjects, on the average, received ten to fifteen conditioning trials depending on their cooperation and availability. Of four subjects who completed the necessary trials evidence for conditioning appeared in two. Magnitude of the conditioned responses is not great, producing, on the average, reduction of about 8% of the vital capacity in five minutes. Both of these subjects show conditioning to the experimental situation; one of the two, conditioning to the exteroceptive stimuli presented by the experimenter. The fact that conditioning did not automatically result from the experimental procedure and the complexity of the conditioning process apparent from detailed examination of the individual cases, led to discussion concerning the nature of conditioning, with special emphasis on the new area of interoceptive conditioning. The author takes the viewpoint that a central emotional-expectancy is an important aspect of conditioned visceral responses, and rejects connectionism between an external stimulus and a response. In addition, one peculiarity of the conditioning done in this experiment is noted. The unconditioned stimulus, rather than acting on the sensory nervous system, produces direct local change in the lungs. The resulting lack of representation of the UCS in the central nervous system is discussed in the reference to classical Pavlovian theory. The writer sees the application of interoceptive conditioning techniques as a fruitful method for further exploration of psychosomatic disorders. [TRUNCATED]

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