Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Three experiments were conducted to investigate Staddon's account of interim activities as induced behaviors which occur at times when a reinforcer is unlikely to be delivered (S('-) times). These experiments examined Staddon's S('-) interpretation of interim behavior by studying drinking and wheel running on various simple and multiple schedules of food reinforcement.;Experiments 1 and 2 were concerned with Staddon's contention that drinking is a representative interim activity which is occasioned by the unavailability of food rather than by the presence of food per se or its ingestion. Contrary to other accounts of schedule-induced polydipsia, this interpretation infers that the link between eating and drinking is not essential for the induction of drinking. In Experiment 1, three rats were exposed to a series of multiple schedules to determine whether drinking occurs during S('-) times that are signalled by events other than food (S('-)(,nonfood)) or is confined to S('-) times signalled by the occurrence of food (S('-)(,food)). Each multiple schedule consisted of a food component, in which reinforcement was delivered on either a fixed or random-interval schedule, and an extinction component, a period when food never occurred. In Experiment 2, drinking was compared in four independent groups of rats exposed to simple or multiple variable-interval or random-interval schedules.;The results of Experiments 1 and 2 indicate that drinking does not occur during an S('-)(,nonfood) even if it predicts the nonoccurrence of food just as well as an S('-)(,food). In all instances, drinking was restricted to S('-)(,food) occasions with very little drinking during the S('-)(,nonfood) extinction component of any multiple schedule. The results also suggest that interim activities differ in the extent to which they can be allocated to S('-)(,nonfood) times. For example, consistently higher levels of wheel running occurred in the extinction component compared to the food component of the multiple schedules.;Behaviors that can be induced by S('-)(,nonfood) occasions are particularly important for Staddon's account of contrast since the effect depends, according to the time allocation model, on the reallocation of interim activities from the food to the extinction component of a multiple schedule. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of school.) UMI



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