Conditioning salivary conditioning

Conditioning as a method for the study of learning was first employed extensively by the Russian physiologist I.P. Pavlov. The response which he selected tor observation was the salivary гейек in A. simple surgical operation moved the opening of the duct of the parotid salivary gland from the inside to the outside of the dog's cheek, so that the flow of saliva could be seen and accurately measured. The original or unconditioned stimulus which elicited the flow of saliva was, in most cases, food. By presenting a neutral stimulus (for example, the ringing of a bell) along with the food for a number of trials, the bell or the conditioned stimulus eventually came to act as a sub­stitute for the food and would cause the saliva to flow even though no food was given. A connection or association had been established between the condit ioned stimulus and the activity of the salivary response or, more simply, the salivary C.R.

Pavlov and his collaborators found in different experiments that many things could be used as conditioned stimuli. Whistles, lights, touching the dog's flank, even mild electric shocks functioned satis­factorily in this capacity. Each of these and many more, when com­bined with food for a sufficient number of trials, produced conditioned salivation. If the food was permanently removed, after a C.R. had been built up, however, continued presentation of the conditioned stimulus alone caused the C.R. to die out gradually. The disappearance of a C.R. under the circumstances was called the extinction of the condi­tion^ Aw could be rapidly ^condi­tioned by reinforcing the conditioned with the unconditioned stimu­lus for a few trials. Even where no reinforcement with the unconditioned stimulus was given, a conditioned response which had been extinguished could be called out at a later time, provided a sufficiently long rest interval had been allowed to elapse after the extinction. The reappearance of a previously extinguished C.R. in this way, without subsequent reinforcement, was called by Pavlov spontaneous recovery.

In applying the salivary conditioning technique to human subjects, two principal methods have been employed. The first of these requires an espe­cially shaped suction cup or saliometer, which fits over the opening of one of the salivary ducts inside the mouth and carries the saliva out of the mouth by means of a small tube. The second method makes use of rolls of dental cotton which are carefully weighed and then placed under the subject's tongue. After a C.R. has occurred, the cotton is removed and weighed again. The difference between the weights before and after the response indicates the amount of saliva which was secreted. The phenom­ena of extinction, reconditioning, spontaneous recovery, and so on, origi­nally discovered by Pavlov on dogs, are all demonstrable in human subjects by one or both of these methods.

(W.N. Kellog. «Conditioning and the Motor Learning.» in «Methods of Psychology», ed. T.G. Andrews. N.Y., 1964, pp. 44 —45).

Read after Lesson V.