Associative status of the training context determines the effectiveness of compound extinction.

Studies of extinction of a target cue in compound with another excitor have produced evidence of both deepened and attenuated extinction relative to elemental extinction. The present experiments sought to resolve this discrepancy by assessing the effect of the extinction context-unconditioned stimulus (US) association on compound extinction. In an ABC renewal situation with rats, Experiment 1 replicated the observation that enhanced extinction (i.e., reduced conditioned suppression) occurs as a result of nonreinforcement in compound with a concurrent excitor. In Experiment 2, inflation of the extinction context-US association through unsignaled, intertrial US presentations reversed the effect of a concurrent excitor (i.e., extinction with a concurrent excitor was less effective than elemental extinction). Experiment 3 compared compound extinction and second-order conditioning with respect to the effect of context inflation, and produced results incompatible with the view that second-order conditioning contributed to the results of Experiment 2. In Experiment 4, a concurrent excitor enhanced extinction in ABC renewal and attenuated extinction in AAC renewal. The present results suggest that the effect of a concurrent excitor during extinction depends on the strength of the extinction context-US association, thereby confirming predictions of the sometimes -competing retrieval model of associative acquisition and extinction.