Evidence for learning-deficit versus performance-deficit theories of latent inhibition in Pavlovian fear conditioning

In a conditioned suppression task with rats, we used retention-interval and context-switch maneuvers in an effort to affect retrieval of interfering associations often held responsible for the effects of preexposing conditioned stimuli (CSs). In Experiment 1, we found that preexposing CS A reduced its subsequent ability to support second-order conditioning to CS X. Inserting a 28-day retention interval between A + and X --> A (second-order conditioning) phases did not restore that ability. It did, however, increase A's ability to acquire conditioned suppression during the second-order phase, suggesting renewed attention to A. In Experiment 2, we found that preexposing CS A reduced its ability to serve later as a blocker. Conducting the blocking test outside the preexposure context did not restore that ability, but conducting the element training phase outside the preexposure context did. Results favor learning-deficit theory over a retrieval-interference version of performance-deficit theory of CS-preexposure effects. (C) 2001 Academic Press.