Context specificity of latent inhibition in taste aversion learning

In three experiments rats were given injections of LiCl after consuming distinctively flavoured water. The rats developed an aversion to the flavour and in all experiments the magnitude of the aversion was found to be reduced in subjects that had received pre-exposure to the flavour without aversive consequences. Experiment 1 demonstrated this pre-exposure effect to be a case of latent inhibition. The remaining experiments investigated the effects of pre-exposing the flavour in a context different from that used for conditioning. It was found (Experiment 2) diat latent inhibition transferred perfectly when the context change consisted of a move from one home cage to another. Context specificity of latent inhibition was found (Experiment 3) only when the subjects were given daily sessions in die experimental contexts, these being cages different from the home cage.     

Contextual conditional discriminations

Three experiments used a discriminated operant procedure to study conditional discrimination learning in rats. The first experiment showed that rats were capable of learning a biconditional discrimination in which two contexts served as conditional cues signalling the reinforcement contingencies associated with two discriminative stimuli. The discrimination was learned equally well when one discriminative stimulus signalled food, the other its absence, and when one stimulus signalled food, the other extinction plus mild footshock.

In Experiment 2 it was shown that prior training on such a conditional discrimination enhanced the subsequent context specificity of simple conditioning relative to control groups of animals for whom the prior training had not been conditional. Experiment 3 showed that a reversal of the significance of one pair of discriminative stimuli produced no spontaneous reversal in performance to a second, target, pair.

The pattern of results is best accounted for by an analysis of contextual conditional discrimination learning in terms of stimulus configurations and offers no support for the notion that rats may learn a general conditional rule or set.