ABSTRACT
Many computer scientists have suggested that intelligent systems, our brains included, are organized into independent modules, as in a digital computer, and we see by processing perceptual qualities, such as form, color, and motion, by using these independent modules. The brain’s organization into processing streams (DeYoe & van Essen, 1988) supports the idea that brain processing is specialized, but it does not in itself imply that these streams contain independent modules. Independent modules should be able to compute fully their particular processes on their own. Much perceptual data argue against the existence of independent modules, however, because strong interactions are known to occur between perceptual qualities (Egusa, 1983; Faubert & von Grunau, 1995; Kanizsa, 1974; Pessoa, Beck, & Mingolla, 1996; Smallman & McKee, 1995). For example, changes in perceived form or color can cause changes in perceived motion, and conversely; and changes in perceived brightness can cause changes in perceived depth, and conversely. How and why do these qualities interact? An answer to this question is needed to determine the functional and computational units that govern behavior as we know it.
