Reward devaluation disrupts latent inhibition in fear conditioning

Reversing the relationship between a nontarget cue and the outcome facilitates subsequent human predictive learning

Two experiments were conducted to test the effect of experiencing associative interference on later learning. A predictive learning task was used in which human participants had to evaluate whether plants would grow or not (Outcome) after being watered with different fertilizers (Cues). Experiment 1 found that the increase in the prediction error produced by following a pre-exposed nontarget cue by the outcome, facilitated subsequent acquisition of the relationship between the pre-exposed target cue and the outcome. Experiment 2 compared whether learning about the target cue was differentially affected by experiencing two types of associative interference with the nontarget cue: Pairing the pre-exposed cue with the outcome and presenting the cue without outcome after being paired with it. The experience of associative interference with nontarget cues similarly facilitated subsequent learning about the target cue, regardless of the direction of the change in the nontarget cue-outcome relationship. It is suggested that the increase in prediction error produced by the experience of associative interference may lead to a general increase in attention that facilitates subsequent learning.

Facilitation and retardation of flavor preference conditioning following prior exposure to the flavor conditioned stimulus

In two experiments, rats received pairings of an almond flavor (Experiments 1 and 2B) or a vanilla flavor (Experiment 2A) with sucrose. In each experiment, half of the rats received prior exposure to the flavor and half were exposed to water. Conditioned preference was then assessed through two-bottle, flavor versus water, choice tests. Latent inhibition (indicated by a weaker preference in pre-exposed subjects) was observed in the experiment using the vanilla flavor. However, facilitation (a stronger preference in pre-exposed subjects) instead of latent inhibition was evident with the almond flavor, both across acquisition trials and in the final choice test. These results indicate that, unlike most other paradigms of Pavlovian conditioning, conditioned stimulus pre-exposure in flavor preference learning may either facilitate or retard the acquisition (or the expression) of a conditioned flavor preference. We explore the proposal that the critical difference between the flavors lies in their hedonic values, with facilitation being more likely in a flavor that is initially disliked.