Table 1 Training and testing schedule for reinforcer magnitude matching task (Experiment 1B) Subjects were trained to respond on two levers (designated A and B) separately and then concurrently under interval schedules of reinforcement. In sessions 8–27, their preference for reinforcers of different magnitudes was assessed. The third column, labelled 'fA', indicates the fraction of responses that would be allocated to lever A [i.e. A/(A+B)] were the subject to obey the matching law [31]. All concurrent (two-lever) schedules were subject to a 2 s changeover delay (COD), described in the Methods.

From: Nucleus accumbens core lesions retard instrumental learning and performance with delayed reinforcement in the rat