Latent Inhibition and Learned Irrelevance of Occasion Setting

Rats received serial feature-positive discrimination training (A → X+/X−) within a conditioned lick suppression preparation (with + representing reinforcement and − representing nonreinforcement). In Experiment 1, the feature (A) was found to modulate responding to a transfer target CS that itself had been occasion set with a second occasion setter, but not to a CS that had been partially reinforced, thereby demonstrating occasion setting with our preparation. Experiments 2–4 examined the effects on the acquisition of occasion setting of various types of pretraining exposure to A. Nonreinforced preexposure to A alone did not in any way retard acquisition and/or expression of occasion setting (Experiment 2), but feature-negative discrimination training did (Experiment 3). A feature-irrelevant pseudo-discrimination pretraining procedure produced profound retardation (Experiment 4). The results of Experiments 2 and 3 indicate that a latent inhibition-like effect for feature-positive occasion setting exists that in some ways is analogous to latent inhibition effects in Pavlovian conditioning. The results of Experiment 4 indicate that an analogue of Pavlovian learned irrelevance can be evidenced for feature-positive occasion setting. The growing parallels between occasion setting and simple Pavlovian conditioning lend support to accounts of occasion setting that view it as arising from an interaction of Pavlovian associations rather than from some distinctly different “higher order” process.