Daniel L. Roe

Date of Award


Degree Name

Master of Arts



First Advisor

Dr. Lisa Baker

Second Advisor

Dr. Alan Poling

Third Advisor

Dr. Neil Kent

Access Setting

Masters Thesis-Campus Only


The effects of resetting and non-resetting fixed-ratio (FR) 20 schedules on accuracy, topography drift ( defined as the number of responses until switching from one lever to the other), rate, and sessions to criteria were examined across doses of cocaine in a two-lever drug-discrimination task. The subjects, male Sprague-Dawley rats, were trained to discriminate 10.0 mg/kg cocaine HCl from saline, then tested at 0.0, 1.25, 2.5, 5.0, and 10.0 mg/kg cocaine. Differences between groups on accuracy, topography drift, and sessions to criteria were small and not statistically significant. The resetting FR 20 group showed consistently higher rates across doses of cocaine than the non-resetting FR 20 group, but this effect was not statistically significant. That statistical significance was not shown between groups on this measure was possibly due to small sample sizes. A large and statistically significant effect was seen across doses on topography drift. This study was one of few attempts to examine the possible differential effects of schedule of reinforcement on drug-discrimination performance.

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