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Behavioral Tolerance Under Variable Ratio Schedules Of Reinforcement, Barry Eshkol Adelman

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Previous studies (e.g., Hoffman, Branch, & Sizemore, 1987) have demonstrated that greater drug tolerance develops in responding under fixed-ratio (FR) schedules of reinforcement when the schedule parameter is small than when it is large; little research has been done on related schedules such as variable-ratio (VR). In Experiment 1, three pigeons responded under a multiple FR 5 FR 125 VR 5 VR 125. A range of prechronic doses of cocaine produced dose-dependent reductions in response rates under the component schedules. Following chronic dosing with daily administrations of 5.6 mg/kg, similar dose-response curves were derived by substitutions of the usual dose. …