Computational analyses and hemispheric asymmetries in visual-form recognition

Much of contemporary theory in cognitive neuroscience adheres to a theoretical framework in which behavioral abilities are understood as arising from the operations of and interactions between relatively independent processing subsystems of the brain. Although these subsystems may be only weakly modular (e.g., Farah, 1994), a primary goal for the field is to discover the broad architecture of interconnected subsystems and to pinpoint the particular functions performed by the various subsystems. In other words, the goal is to understand how the brain is “carved at its joints ” (e.g., Kosslyn & Koenig, 1992) or, perhaps more appropriately given weak modularity, “stretched at its interconnections ” into relatively independent functional entities. This quest for component subsystems is especially important in understanding functional hemispheric asymmetries. Theories that are cast in terms of how component subsystems operate more or less effectively in different hemispheres are providing more powerful and compelling explanations than those that rely on general principles or fundamental dichotomies (see Hellige, 1993a). In order to theorize about the function of any system, one must characterize how inputs are mapped to outputs by the system. Inputs, outputs, and the couplings between the two are needed to describe any function; if one of these three elements is missing or vague, no matter which one, a functio