Effect of AcbC lesions on acquisition of free-operant responding with delayed reinforcement Data plotted to show the effects of AcbC lesions (same data as in the previous figure). There was a delay-dependent impairment in AcbC-lesioned rats, who learned less well than shams only when reinforcement was delayed. (a) With a delay of 0 s, AcbC-lesioned rats learned just as well as shams; in fact, they responded more on the active lever than shams did. (b) With a 10 s delay, AcbC-lesioned rats were impaired at learning compared to shams. (c) With a 20 s delay, the impairment in AcbC-lesioned rats was larger still.