Perceptual learning in flavor aversion conditioning: Roles of stimulus comparison and latent inhibition of common stimulus elements

In three experiments, rats received training in which an aversion was established to one flavor and the extent to which this aversion generalized to a second flavor was tested. Experiment 1 showed that nonreinforced preexposure to both flavors resulted in reduced generalization between them. Experiments 2 and 3 demonstrated that this reduction in generalization required the two flavors to be presented on alternate trials during preexposure. Subjects given preexposure consisting of a block of trials with one flavor followed by a block of trials with the other showed the same degree of generalization as subjects given no preexposure. The two schedules of stimulus presentation were equated in the total amount of exposure given to each stimulus, making it unlikely that differences in latent inhibition could be responsible for the difference seen on the test. It is suggested that the opportunity for stimulus comparison offered by the alternating schedule might be important in a process of perceptual learning that is responsible for the reduced generalization.