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| A Wrinkle in Timing Accounts: Effects of D-amphetamine and Morphine |
| Monday, May 31, 2004 |
| 3:30 PM–4:20 PM |
| Beacon E |
| Area: BPH |
| Chair: Clive D. L. Wynne (University of Florida) |
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| The Effects of Morphine on the Discrimination of Subject-produced and Experimenter-imposed Durations |
| Domain: Applied Research |
| RYAN D. WARD (Utah State University), Amy Odum (Utah State University) |
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| Abstract: Experiments that assess animal timing of durations usually present a sample and require the animal to categorize the duration. Discrepancies in the timing literature have led some to conclude that the mechanisms underlying timing of experimenter-imposed durations may be different than those used to time subject-produced durations. As a result, different timing procedures may lead to different, and conflicting results. Experiment 1 used a procedure developed by Shimp (1981) in which pigeons categorized the duration of their interresponse times. Pecks on a center key produced DSMTS trials on a random interval schedule. Pecks to a key lit one color led to food if the previous interresponse time was short, and pecks to another key led to food if the previous interresponse time was long. When matching accuracy was stable and asymptotic, we examined the effects of acute morphine administration. Morphine dose dependently flattened the interresponse time distributions and decreased accuracy. Accuracy for short interresponse times was less affected than accuracy for long interresponse times. In a second experiment, we used a procedure that allowed us to assess the effects of morphine on the discrimination of both subject-produced and experimenter-imposed durations, within the same session. |
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| Effects of D-amphetamine on Peak Interval Responding in Pigeons |
| Domain: Applied Research |
| CLIVE D. L. WYNNE (University of Florida), Kathryn A. Saulsgiver (University of Florida), Erin McClure (University of Florida) |
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| Abstract: We analyzed the effects of four doses of d-amphetamine (0.75, 1.5, 2.25 and 3.0 mg/kg) on a Peak Interval (PI) responding in pigeons. Discrete trial Fixed Intervals (FI) trials were intermixed with PI trials, which terminated without reinforcement. Drug was administered for ten consecutive daily sessions followed by at least ten days of saline baseline recovery. Analysis of the peak times assessed by three methods (fitting Weibull and Gaussian functions, finding the midpoint of the interquartile range) revealed no change at any drug dose. However, times to first response (wait times) were also examined and showed a dose-dependent decrease with the administration of d-amphetamine and a increase in both time and variability when d-amphetamine was removed. |
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