Facilitation and retardation of discrimination learning after exposure to the stimuli.

In three experiments, rats was required to learn a simultaneous discrimination in a jumping stand between horizontally and vertically striped objects. Experiment 1 showed that prior prolonged exposure to these stimuli in the rats' home cages helped them to learn the discrimination. Experiment 2 showed that a briefer period of exposure (1 hr per day for 50 days) was equally effective when the stimuli were presented in the home cage but produced a retardation of discrimination when the stimuli were presented in the jumping stand itself. Experiment 3 demonstrated that prior exposure to the jumping stand was not in itself enough to produce a retardation of subsequent discrimination learning. Some implications of these results for current theories of perceptual learning and latent inhibition are discussed.