The Emergence of Behavioral Pharmacology

Effects of drugs depend on past experience (i.e., conditioned schedules of reward) and ongoing behavior. Effects of pentobarbital and amphetamine under a multiple fixed-interval (FI; 10 min) fixed-ratio (FR; 31 pecks) response schedule of reinforcement. Administration of pentobarbital decreases response (i.e., pecking) rates under the FI schedule without affecting response rates under the FR schedule. Amphetamine produces just the opposite: response rates under the FI schedule increase while the response rate under the FR schedule becomes negligible (shown by the bracketed areas). From (2) .