Abstract
Rats were trained to discriminate phenobarbital (50 mg/kg) vs saline in a two-bar, thirst-motivated operant drug discrimination task. Presses on bar 1 were reinforced when the rat was drugged and presses on bar 2 when not drugged. Several shaping procedures and schedules of reinforcement were compared to determine which would allow drug discriminations to be learned most rapidly, and which would result in the higherst asymptotic accuracy of discrimination. The discrimination was learned more rapidly when differential drug conditions were used from the very first day of training than when shaping on both bars was completed before the differential drug conditions were introduced. Variable interval (VI), fixedratio (FR), and differential reinforcement of low rate (DRL) schedules were tested as well as several more complex schedules. Asymptotic accuracy of discrimination was highest when FR, interlocking FR 10/FI90″, or DRL 16″ schedules were used; accuracy was intermediate when a tandem VI 20″/FR 10 schedule was used; accuracy was relatively low when a VI 20″ schedule was employed. When the optimal shaping procedure and schedule of reinforcement were used, highly accurate drug discriminations were learned much more rapidly than has previously been reported. The results are discussed with reference to control of differential responding by contextual and discriminative stimuli.
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Overton, D.A. Influence of shaping procedures and schedules of reinforcement on performance in the two-bar drug discrimination task: A methodological report. Psychopharmacology 65, 291–298 (1979). https://doi.org/10.1007/BF00492218
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DOI: https://doi.org/10.1007/BF00492218