Date of Graduation


Document Type


Degree Type



Eberly College of Arts and Sciences



Committee Chair

Kennon A. Lattal.


The purpose of the present experiments was to examine the relation between timing and response strength. Pigeons responded on a two-component multiple schedule consisting of the free-operant psychophysical procedure, in which trials lasted 50 s. During the first 25 s of each trial, responding on the left key was reinforced according to a variable interval (VI) schedule of reinforcement. During the second 25 s of each trial, responding on the right key was reinforced according to a VI schedule of reinforcement. In Experiment 1, responding in one component was maintained by a VI 30-s schedule (rich component) and responding in the other component was maintained by a VI 120-s schedule (lean component). In Experiment 2, responding in both components was maintained by a VI 60-s schedule, but reinforcement consisted of 6.5-s access to grain (rich component) in one component and 1-s access to grain in the other (lean component). Responding then was disrupted by adding response-independent food delivery during the intertrial interval and by prefeeding. In general, the results of both Experiments 1 and 2 are consistent with the existing literature: response rates and ET50s (the index of timing) were more disrupted during the lean components than during the rich components. The effects of the disruptors provided partial support for the Behavior Theory of Timing (BeT). In addition, during the rich components, time was overestimated relative to estimations of time during the lean components. It is suggested that temporal control and response strength are related in the sense that both measures tend to vary in a manner consistent with predictions based on the BeT and the response strength literature.