In their preoccupation with the associative mechanisms of learning, psychologists have tended to overlook those instances of behavioral change whose associative basis was not evident. Thus, habituation and latent inhibition, two response-decrement effects of experience with single, isolated stimulus, have received very little empirical or theoretical attention from the learning theorist. Of late, however, it has become increasingly evident that a complete account of the learning process must include an analysis of these two phenomena. The proposed experiments are designed to test certain deductions from a recent (and, ironically, associationist) theory of habituation and latent inhibition (Wagner, 1976). The experiments, each employing rat subjects in a conditioned emotional response procedure, will test the theory's predictions that (1) latent inhibition of a stimulus (S1) during both pre-exposure trials and test trials; (2) latent inhibition of S2 should be weakened if S2 is preceded by S1 during pre-exposure but not in the test; (3) exposure to S1 following S1-S2 pairings should weaken the latent inhibition of S2; and (4) exposure to S1 prior to S1-S2 pairings should weaken the latent inhibition of S2. This research should enhance our understanding of latent inhibition, associative learning, and the ways in which these interact.