Latent inhibition of a CS during CS-US pairings.

In each of three experiments rats were trained by the conditioned-emotional-response technique with a conditioned stimulus (CS) predicting a relatively weak shock, the unconditioned stimulus (US). In the second stage of training the intensity of the shock was increased, and it was found that subjects for whom the same CS was used in both stages acquired further suppression less readily than subjects that experiences a new CS in the second stage. The implication of these results for theories of attention and for theories of habituation is discussed. It is suggested that associations formed by the test CS during the first stage of training reduce the readiness of the stimulus to enter into new associations, either because an association between the stimulus and the context reduces further processing of the stimulus or because the association between the test stimulus and the weak shock attenuates the formation of an association with the stronger shock.