Latent inhibition in flavor-preference conditioning: effects of motivational state and the nature of the reinforcer.

In two experiments, rats received pairings of the flavor of almond with either fructose or maltodextrin, and the conditioned preference for almond was then tested. In each experiment, half of the rats had received prior exposure to almond on its own, and half had received no preexposure. In Experiment 1, in which the rats were hungry during the test, the preference was greater in the nonpreexposed subjects, both for those trained with fructose and those trained with maltodextrin; that is, latent inhibition was obtained with both reinforcers. In Experiment 2, in which the rats were not food deprived prior to the test, not only was there no latent inhibition with either of the reinforcers, but, for both, the preference was greater for preexposed than for nonpreexposed subjects. These results give no support to the proposal that different types of reinforcer generate different types of learning. They are, however, consistent with the proposal that different types of learning control behavior when a rat is hungry and when it is not, and that the form that generates the preference in the latter case is not susceptible to the latent inhibition effect.