Cue competition as a retrieval deficit

Four experiments using rats as subjects investigated the claim of Williams (1996) that cue competition results from an associative acquisition deficit, rather than a performance deficit. In Experiment 1, extinction of an overshadowing stimulus following overshadowing treatment increased responding to the overshadowed stimulus, thereby replicating prior observations with new parameters. In Experiment 2, an overshadowed stimulus failed to support second-order conditioning unless the overshadowing stimulus received prior extinction treatment. Experiment 3 replicated the recovery from overshadowing effect seen in Experiment 1 using a sensory preconditioning procedure. Most important, in Experiment 4 an overshadowed stimulus failed to block conditioned responding to a novel CS, but blocking by the overshadowed cue was observed following posttraining extinction of the overshadowing stimulus. These results, as well as those of Williams, are discussed in terms of traditional and more recent acquisition-focused models as well as an extension of the comparator hypothesis (Denniston, Savastano, & Miller, 2001).