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A K Reid

Publications and source records attributed to A K Reid.

6 recordsLinked to original sources
PubMed2001

The development of functional response units: the role of demarcating stimuli.

An experiment with rats examined the roles of demarcating stimuli and differential reinforcement probability on the development of functional response units. It examined the development of units in a probabilistic, free-operant situation in which the presence of demarcating stimuli was manipulated. In all conditions, behavior became organized into two-response sequences framed by changes in local reinforcement probability. A tone demarcating the beginning and end of contingent response sequences facilitated the development of functional response units, as in chunking, but the same units developed slowly in the absence of the tone. Complex functional response units developed even though reinforcement contigencies remained constant. These findings demonstrate that models of operant learning must include a mechanism for changing the response unit as a function of reinforcement history. Markov models may seem to be a natural technique for modeling response sequences because of their ability to predict individual responses as a function of reinforcement history; however, no class of Markov chain can incorporate changing response units in their predictions.

Animals↗
PubMed1993

The temporal organization of behavior on periodic food schedules.

Various theories of temporal control and schedule induction imply that periodic schedules temporally modulate an organism's motivational states within interreinforcement intervals. This speculation has been fueled by frequently observed multimodal activity distributions created by averaging across interreinforcement intervals. We tested this hypothesis by manipulating the cost associated with schedule-induced activities and the availability of other activities to determine the degree to which (a) the temporal distributions of activities within the interreinforcement interval are fixed or can be temporally displaced, (b) rats can reallocate activities across different interreinforcement intervals, and (c) noninduced activities can substitute for schedule-induced activities. Obtained multimodal activity distributions created by averaging across interreinforcement intervals were not representative of the transitions occurring within individual intervals, so the averaged multimodal distributions should not be assumed to represent changes in the subject's motivational states within the interval. Rather, the multimodal distributions often result from averaging across interreinforcement intervals in which only a single activity occurs. A direct influence of the periodic schedule on the motivational states implies that drinking and running should occur at different periods within the interval, but in three experiments the starting times of drinking and running within interreinforcement intervals were equal. Thus, the sequential pattern of drinking and running on periodic schedules does not result from temporal modulation of motivational states within interreinforcement intervals.

Animals↗
PubMed1987

Within-session meal-size effects on induced drinking.

As a control for the effects of session duration and hunger on the relation between food magnitude and induced drinking, four food-deprived rats were exposed to a variable-time 50-s schedule of food delivery in which the size of each food delivery varied randomly within sessions. Food-related behavior and schedule-induced drinking per opportunity were examined as functions of meal size and postfood time. All rats showed an inverted-U-shaped relation between drinking per opportunity and meal size. This relation was caused by variation in the percentage of intervals that contained drinking and by variation in the number of drinking bouts per interval, rather than by bout duration or by the amount of drinking within those intervals that actually contained drinking. Head-in-feeder time increased linearly with meal size. Schedule-induced drinking was entrained by food delivery in 3 of 4 subjects; the entrainment was due to regulation of the starting time of each drinking bout rather than to regulation of bout duration.

Animals↗
PubMed1983

Dynamic effects of food magnitude on interim-terminal interaction.

We tested the assumption of a facilitatory relation between periodic food presentation and schedule-induced drinking by examination of (a) elicited drinking, (b) drinking in anticipation of food delivery, and (c) possible indirect effects of food delivery on drinking. We exposed rats to a fixed-time 60-second schedule in which interfood intervals ended in either one or four food pellets with equal probability. In Phases 1 and 3, a stimulus signaled the magnitude of upcoming food presentation. In Phase 2, the stimulus was eliminated. Changes in drinking and "head-in-feeder" distributions within interfood intervals demonstrated that head-in-feeder was controlled directly by food presentation, but drinking was not. Head-in-feeder increased and drinking was reduced when large meals began or ended an interval. In Phases 4 to 6, meal size was manipulated across sessions yielding a positive relation between meal size and schedule-induced drinking. We conclude: (1) Schedule-induced drinking is determined by distributions of food-related behavior and results from indirect effects of food delivery; and (2) the amount of schedule-induced drinking and the form of the drinking distributions in this experiment can be accurately explained by two assumptions: (a) Food presentation facilitates food-related behavior through elicitation and anticipation; and (b) food-related behavior and drinking are reciprocally, linearly related.

Journal Article↗
PubMed1982

Schedule-induced drinking: Elicitation, anticipation, or behavioral interaction?

We carried out five experiments with rats on fixed-time schedules in order to define the relation between drinking and individual food-pellet presentations. In Experiment 1, unsignaled extra food occurred at the end of occasional fixed intervals, and we compared subsequent drinking patterns with drinking before the extra food presentation. In Experiment 2 we presented signaled and unsignaled extra food and measured elicited and anticipatory drinking patterns. In Experiment 3, we observed the persistence of modified drinking patterns when several consecutive intervals ended with extra pellets. In Experiments 4 and 5, we varied the magnitude of food delivery across (rather than within) sessions to replicate published findings. Results show that schedule-induced drinking is neither elicited by food presentations nor induced by stimuli associated with a high food rate. All subjects seemed to follow a simple rule: during any stimulus signaling an increase in the local probability of food delivery within a session, engage in food-related behavior to the exclusion of drinking. Schedule-induced drinking appears to be the result of dynamic interactions among food-related behavior, drinking, and other motivated behavior, rather than a direct effect of the contingencies of food reinforcement.

Journal Article↗