Enhancement of Responding to A After A/AX Training: Challenges for a Comparator Theory of Learning

Two appetitive Pavlovian conditioning experiments with rats investigated the associative changes that A undergoes in an A/AX blocking procedure. Conditioned responding to A was enhanced relative to stimulus B, which had been conditioned in isolation (B). This result was interpreted in terms of the formation of a within-compound association between A and X. The results of Experiment 2 supported this conclusion by demonstrating that X had associative strength of its own and, furthermore, that extinguishing X resulted in a similar level of responding to A and B. These results are considered in terms of retrospective revaluation theories of learning