Loss of Latent Inhibition in Conditioned Taste Aversion following Exposure to a Novel Flavour before Test

Abstract

Killcross, Kiernan, Dwyer, and Westbrook (1998b) observed that latent inhibition(LI) of contextual fear was attenuated if animals received post-conditioning exposure to a novel context similar to the pre-exposure context. Six experiments used a conditioned taste aversion (CTA) procedure to examine this effect. Experiments 1A–1C demonstrated that LI of CTA was attenuated by a similar post-conditioning manipulation, establishing the generality of previous findings. Experiment 2A manipulated the taste elements to which animals were exposed after conditioning, revealing that exposure to a common element X, present at pre-exposure and conditioning, was not responsible for loss of LI. Experiment 2B manipulated test solution and showed that loss of LI depended on the presence of the full pre-exposed cue AX at test. These two results are contrary to predictions derived from the Dickinson - Burke (Dickinson & Burke, 1996) theory of retrospective revaluation or comparator theory (Miller & Matzel, 1988), and they support recent findings suggesting that retrospective effects may occur by several mechanisms. Experiment 3 showed that a novel element B had to be present during post-conditioning exposure for an attenuation of LI to be observed. Implications for the loss of LI following a retention interval between conditioning and test and retrieval-failure theories of LI are discussed.