The context effect: The relationship between stimulus preexposure and environmental preexposure determines subsequent learning.

Perceptual learning studies indicate that stimulus preexposure enhances subsequent learning, while latent inhibition studies indicate that stimulus preexposure retards subsequent learning. An analysis of the two paradigms suggests that predictions in regard to the effects of stimulus preexposure must take into account not only the novelty of the stimulus, but the relationship of that novelty to that of the environment at the time of testing. Two studies with identical designs, one with children and one with rats, are reported. In both studies, enhancement of learning is achieved when a new stimulus is presented in an old environment or an old stimulus in a new environment as compared to either a new stimulus in a new environment or • an old stimulus in an old environment. This demonstrates latent inhibition and perceptual learning, and shows that the direction of the effects of stimulus preexposure is dependent on the relative novelty of the environment. A two-process theory based on enhancing salience through conditioning and arousal is proposed to account for the pattern of results.