EFFECTS OF CHLORDIAZEPOXIDE AND d‐AMPHETAMINE ON RESPONDING SUPPRESSED BY CONDITIONED PUNISHMENT

Key pecking by two pigeons, maintained under a variable‐interval two‐minute schedule of food presentation, was suppressed when each response produced a five‐second visual stimulus that was occasionally paired with shock. Stimulus‐shock pairings occurred independently of responding according to a variable‐time six‐minute schedule for one bird or once per session for the other bird. The effects of chlordiazepoxide and d ‐amphetamine were assessed on this baseline of behavior suppressed by conditioned punishment. Chlordiazepoxide produced dose‐related increases in the rate of punished responding, whereas d ‐amphetamine produced only decreases. In addition, chlordiazepoxide produced dose‐related increases in response rate during the response‐produced and response‐independent stimulus presentations; d ‐amphetamine, however, only decreased responding during stimulus presentations.