Figure 1.

Effects of cocaine on instrumental conditioning and sensitivity to outcome devaluation. (a) Mean (+SEM) lever presses across 2-day blocks of instrumental training. Lever-press rates increased across training but there were no group differences in lever-press rates indicating equivalent instrumental performance during training. (b) Mean (+SEM) lever presses following prefeeding of the earned (devalued) or control (nondevalued) food outcome in tests conducted relatively early (when rats had earned 300 rewards) or late (when rats had earned 540 rewards) in training. In the Early test, both groups showed equivalent sensitivity to outcome devaluation decreasing performance following prefeeding of the earned outcome. In the Late test, although rats previously treated with saline remained sensitive to devaluation, performance of those previously treated with cocaine was no longer sensitive to devaluation, demonstrating that performance in these animals had come under habitual control. N=8–9 rats per group, *significant devaluation effect.