Eight rats (Rattus norwegicus) were individually exposed to either closed or open economies in a multioperant experimental setting with a proportional ratio reinforcement contingency imposed. Completion of successive ring pull ratios accrued visually signaled opportunities for access to food and/or water via further ratio completions on distinct levers. Successive pellet or water presentations decreased the remaining available food and water opportunities and when the last opportunity was depleted, subjects were returned to the ring pull option only. Experiment 1 compared the effects of a simple and forced savings proportional schedule. Rats "saved" when required to by the forced trials condition but substantial savings occurred in the simple proportional schedule irrespective of forced trials training. Assessment of responses occurring in the presence of specific discriminative stimuli indicated that the relevant operants were under adequate stimulus control. No systematic differences were observed in savings responses within closed or open economies and subsequent work was conducted in an open economy. Three of the subjects exhibited low rates of extended ring pull runs while five of the subjects emitted moderate to high savings responses. Experiment 2 compared the conditional probabilities of feeding and drinking bouts under a proportional schedule and a "free-choice" condition. Distributions of feeding and drinking bout lengths were similar across all subjects under the free-choice baseline and were not seen to covary in any way with the differences in ring pull run lengths observed among subjects under the proportional schedule conditions. Experiment 3 shifted each subject's baseline distribution of save runs to a higher proportion of extended save runs by increasing the response cost on the terminal food and water ratios following short save runs. Overall, the proportional schedule generated rates of saving, hoarding and putative examples of "self-control" in rats that were substantially greater than those previously reported in operant hoarding or self-control literature. The implications of proportional schedule effects for human performance are discussed.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-8053 |
| Date | 01 January 1991 |
| Creators | Carlson, Eric Lawrence |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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