Bidirectional instrumental conditioning.

Three experiments examined bidirectional instrumental conditioning by training hungry rats to push a pole in one direction for food pellets and in the other for either a sugar or a starch solution. In the first study we examined whether the animals learned about the action-reinforcer relations using a specific satiety procedure. Prefeeding one type of reinforcer before an extinction test selectively depressed the performance of the action that had been paired with this reinforcer during training. The second experiment investigated the sensitivity of the bidirectional actions to variations in the action-reinforcer contingencies. When the instrumental contingency was degraded by presenting unpaired reinforcers, the animals pushed less in the direction that was paired with the reinforcer type that was the same as the non-contiguous one. A third study revealed that increasing the rate of reinforcement for one action enhanced its rate of performance without significantly affecting the performance of the other action. We conclude that the effects of reinforcer devaluation, the action-outcome contingency, and the rate of reinforcement are not mediated by Pavlovian associations between the manipulandum and the reinforcer.