Figure 2.

Diagram of behavioral procedures and behavioral responding. A, Rats were trained for 5 d on one of three partial reinforcement procedures (“reward-predictive cue,” “random cue,” and “response-contingent cue”) wherein ∼50% of operant responses at a nosepoke operandum were reinforced with subsequent sucrose delivery at an adjacent port. On the sixth day, an abbreviated training session was immediately followed by an unexpected within-session extinction procedure wherein operant responses were not reinforced and sucrose solution was not available. B, C, Mean nosepoke (B) or port entry (C) responses (in 10 min bins) are shown across the maintenance and extinction segments of the within-session extinction procedure for each treatment group (n = 5 rats each group); error bars indicate SEM.