Semester

Summer

Date of Graduation

2026

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Psychology

Committee Chair

Kennon A. Latta

Committee Member

Karen G. Anderson

Committee Member

Ryan Best

Committee Member

John V. Keller

Committee Member

Michael Perone

Abstract

Adaptation is the continual process of behavioral change in response to changes in environmental contingencies. One example of adaptation is to track the temporal distribution of reinforcers. The present dissertation investigated how responding tracked cyclically changing reinforcement schedules (i.e., cyclic interval [CI]) and how such tracking was influenced by concurrently available alternative reinforcement schedules. Across two experiments, four pigeons responded under a CI 60-s schedule in which the interreinforcer intervals (IRIs) changed systematically according to a sinusoidal function. The primary dependent variable was postreinforcement pauses (PRPs), with local response rates (response rates per IRI) examined as a secondary measure of tracking. Tracking was assessed using moving averages, cross-correlation function (CCF), and spectral analysis. Experiment 1 was designed to investigate how different rates of alternative reinforcement (extinction, variable interval [VI] 20 s, VI 60 s, and VI 180 s) influenced responding under the CI schedule. Tracking was evident when the alternative reinforcement rates were leaner than the CI schedule, whereas richer alternative rates disrupted tracking, reducing alignment between PRPs and IRIs. Experiment 2 was designed to investigate within-session transitions between alternative reinforcement rates (VI 20 s and VI 180 s) and the effects of discriminative stimuli associated with the alternative rates (mixed versus multiple schedules). Tracking varied systematically with the alternative rate, with stronger tracking during the VI 180-s component than during the VI 20-s component. Discriminative stimuli produced minimal additional effects relative to the alternative rate itself. The findings across experiments demonstrated that concurrent reinforcement context altered the extent to which responding adapted to the CI IRIs. These findings extend prior research on cyclic schedules, schedule interactions, and behavioral dynamics by demonstrating that tracking depended not only on the CI schedule itself but also on alternative sources of reinforcement. The findings are discussed by conceptualizing reinforcement schedules as input signals and behavior as an adaptive output shaped by environmental conditions.

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