Is perception informationally encapsulated? The issue of the theory-ladenness of perception

Fodor has argued that observation is theory neutral, since the perceptual s ystems are modular, that is, they are domain-specific, encapsulated, mandat ory, fast, hard-wired in the organism, and have a fixed neural architecture . Churchland attacks the theoretical neutrality of observation on the groun ds that (a) the abundant top-down pathways in the brain suggest the cogniti ve penetration of perception and (b) perceptual learning can change in the wiring of the perceptual systems. In this paper I introduce a distinction b etween sensation, perception, and observation and I argue that although Chu rchland is right that observation involves top-down processes, there is als o a substantial amount of information in perception which is theory-neutral . I argue that perceptual learning does not threaten the cognitive impenetr ability of perception, and that the neuropsychological research does not pr ovide evidence in favor of the top-down character of perception. Finally, I discuss the possibility of an off-line cognitive penetrability of percepti on. (C) 2001 Cognitive Science Society, Inc. All rights reserved.