Effects of D-Amphetamine in a Temporal Discrimination Procedure: Selective Changes in Timing or Rate Dependency?

Document Type

Article

Journal/Book Title/Conference

Journal of the Experimental Analysis of Behavior

Volume

78

Issue

2

Publisher

Society for the Experimental Analysis of Behavior

Publication Date

2002

First Page

195

Last Page

214

Abstract

Two experiments evaluated rate dependency and a neuropharmacological model of timing as explanations of the effects of amphetamine on behavior under discriminative control by time. Four pigeons pecked keys during 60-trial sessions. On each trial, the houselight was lit for a particular duration (5 to 30 s), and then the key was lit for 30 s. In Experiment 1, the key could be lit either green or blue. If the key was lit green and the sample was 30 s, or if the key was lit blue and the sample was 5 s, pecks produced food on a variable-interval 20-s schedule. The rate of key pecking increased as a function of sample duration when the key was green and decreased as a function of sample duration when the key was blue. Acute d-amphetamine (0.1 to 3.0 mg/kg) decreased higher rates of key pecking and increased lower rates of key pecking as predicted by rate dependency, but did not shift the timing functions leftward (toward overestimation) as predicted by the neuropharmacological model. These results were replicated in Experiment 2, in which the key was lit only one color during sessions, indicating that the effects were not likely due to disruption of discriminative control by key color. These results are thus consistent with rate dependency but not with the predictions of the neuropharmacological model.

Comments

Originally published by the Society for the Experimental Analysis of Behavior. Publisher's PDF available through remote link.

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