Effects of reinforcer limitations on fixed-ratio responding during repeated administration of chlorpromazine.

Key-pecking was maintained under a 30-response fixed-ratio schedule of food presentation and pigeons received 30 mg/kg/day chlorpromazine immediately prior to experimental sessions. After responding stabilized during chronic drug and animals were receiving all available reinforcers, the time available for receiving reinforcers was systematically varied. When that time was decreased, animals initially received fewer reinforcers but responding subsequently increased to an extent that animals once more received all available reinforcers. When that time was again increased, responding once again decreased but only to an extent that animals continued receiving all available reinforcers. During subsequent reversals of the time for reinforcer availability, responding increased or decreased to an extent always resulting in the maximum number of reinforcers. When drug was discontinued, responding returned to predrug levels. These results demonstrate that effects of chronically administered chlorpromazine were influenced by both drug activity at its site of action and by the behavioral process of reinforcement.