Date of Award

Spring 1992

Project Type

Dissertation

Program or Major

Psychology

Degree Name

Doctor of Philosophy

First Advisor

William M Baum

Abstract

Is moving from place to place equivalent to pressing a lever or pecking a key? This dissertation addressed this question by comparing natural travel (moving from place to place) with artificial travel requirements (to press on a lever). In two experiments foraging was modeled with operant behavior. Rats "searched" for food by pressing on the left lever. The patch provided a maximum of 1, 2, or 8 pellets. When the patch provided 1 pellet, rats captured the first prey with a.10 probability. The probability dropped to zero after one pellet. When the patch provided 2 or 8 pellets rats captured the first prey with a 1.0 probability. Each prey delivered on the left lever caused this probability to decrease to 0 in steps of.5 or.125 simulating patch depletion. Lever-press on the right lever reset the probability on the left lever to.10 or 1.0. To model artificial travel different reset-probabilities were scheduled on the right lever. The experimental situation was modified to model natural travel. Rats had to run 520 cm to travel back and forth between left and right levers. Experiments 1 and 2 revealed that as the number of available prey in the patch increased the giving-up time increased. Experiment 1 showed that natural travel produced longer residence and giving-up times than the artificial travel conditions. Experiment 2 revealed that by pressing on retractable levers, rats made shorter residence and giving-up times than by pressing on standard levers. Sometimes, but not in systematic way, natural travel produced longer residence and giving-up times than by responding to the reset-probabilities. The natural travel with obstacles produced the longest residence and giving-up times. The natural travel with obstacles had more of an effect on residence and giving-up times than any other travel requirement. The residence and giving-up times obtained in Experiments 1 and 2 are in accordance with predictions derived from McNair's (1982) model. As the travel requirement increased the residence and giving-up time increased. This is predicted because the average rate of capture decreased as travel time increased.

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