Date of Award:

8-2012

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Psychology

Committee Chair(s)

Amy L. Odum

Committee

Amy L. Odum

Committee

Kerry E. Jordan

Committee

Timothy A. Shahan

Abstract

Enhanced memory that is less susceptible to disruption has been demonstrated previously, by presenting more reinforcement for correct responses (e.g., a higher probability of reinforcement) in a conditional discrimination task. The purpose of the present experiment was to extend our current understanding of this phenomenon to a different dimension of reinforcement (i.e., magnitude). This would offer additional techniques for delivery of reinforcement within applied settings (e.g., a classroom) that could promote accurate and persistent memory. The present experiment, therefore, was conducted to investigate the effects of reinforcer magnitude on resistance to disruption of remembering and response rates. Pigeons were exposed to a variable-interval (VI), delayed-matching-to-sample procedure (DMTS) with two components (rich and lean). Specifically, completion of a VI 20-second (s) multiple schedule resulted in DMTS trials in both components. In a DMTS trial, a choice of one of two comparison stimuli (e.g., blue key) results in reinforcement if the choice matches some property of the sample stimulus presented previously. The sample and comparison stimuli are separated by a delay. Four delays (0.1, 4, 8, and 16 s) were used between the sample and comparison stimuli in the present study, and were presented equally across rich and lean components. The difference between rich and lean components was the length of hopper duration (either 4.5 s [rich component] or 0.75 s [lean component]) following a correct response. After baseline performance was established, memory was tested with disruptive conditions (extinction, ICI food, lighting the houselight during delays, and prefeeding). Results showed that during baseline, accuracy was higher in the component with more reinforcement access (4.5 s) relative to the component with less (0.75 s), and accuracy decreased as delays increased in both components. Remembering was also more resistant to disruption in the component with more reinforcement access. These results suggest that providing greater length of access to reinforcement in applied settings may be an effective way to increase accuracy and persistence in memory.

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This work made publicly available electronically on July 31, 2012.

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