Are expectancies based upon different positive reinforcing events discriminably different?

Abstract

Two experiments are reported which bear upon the question of whether the expectancy aroused by a signal for solid food is discriminably different from that aroused by a signal for sucrose. The first experiment demonstrated in a response choice task that rats will learn to make R 1 (pressing one of two bars) to S 1 and R 2 to S 2 faster if correct S 1-R 1 occurrences are reinforced with food and correct S 2-R 2 occurrences with sucrose, than if both S-R chains are reinforced with the same agent. The second experiment demonstrated that rats learn the S 1-R 1-S 1 R , S 2-R 2-S 2 R problem faster if they have received pretraining in which S 1 is simply paired with S 1 R and S 2 with S 2 R than if the pretraining is the reverse of the stimulus-reinforcer pairings encountered in the choice task. These results are interpreted as indicating that different reinforcers establish distinctively different expectations which can function as part of the discriminative stimulus complexes for the correct responses.