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.

Savings tests: Separating differences in rate of learning from differences in initial levels.

“…The present design calls for a within-subject comparison in which the same subject is conditioned with one preexposed and one nonexposed stimulus. Although there are a few demonstrations of latent inhibition within the same subject (e.g., Killcross & Robbins, 1993), there is also some evidence that latent inhibition can be sharply reduced by the presentation of another stimulus following preexposure (e.g., Killcross, 2001). Such a presentation is an inevitable consequence of conducting a within-subject experiment and may have contributed to the small effect observed here.…”

An empirical analysis of the super-latent inhibition effect

“…In three experiments, they found that LI was greater after a 21-day conditioning-test interval than after a 1-day interval A review of the CTA literature on LI and delay reveals several procedural differences that may account for the apparently contradictory results. As has been noted by De la Casa and Lubow (2000) and Killcross (2001), experiments reporting delay-induced attenuation of LI have been conducted in the animals' home cages (e.g., Aguado et al, 1994). Conversely, experiments obtaining intact LI (Álvarez & López, 1995) or super-LI used preexposure, conditioning,and test contexts that were different from the delay context.…”

Circadian-temporal context and latent inhibition of conditioned taste aversion: Effect of restriction in the intake of the conditioned taste stimulus

“…In this condition, both the PE-S and PE-D subgroups showed latent inhibition, and the magnitude of taste aversion over the test days was lower in these subgroups with respect to the nonpreexposed animals, regardless of a change in the temporal context. All these findings can hardly be attributed to a contextual effect on the retrieval of learning (Killcross, 2001;Maren & Holt, 2000) because the context in the test days (evening session) should not point to the conditioned stimulus-unconditioned stimulus association in the PE-D subgroup without restriction in the intake of the taste stimulus (and therefore this subgroup should express latent inhibition). Rather, the effect of a change of the temporal context on latent inhibition may be due to contextual influences on the association between stimuli (Hall, 1991;Kwok & Boakes, 2015;Lubow & De la Casa, 2005;Schmajuk, Lam, & Gray, 1996).…”