Interpreting double dissociations in connectionist networks.

A common motivation for studying the cognitive impairments of brain-damaged patients is to determine the “functional architecture” of the cognitive system. But what constitutes a functional architecture? This question used to have a straightforward answer: a set of discrete components with communication pathways among them, with each component assigned a specific function or type of representation. With the additional assumption that brain damage can (and occasionally does) impact individual components or pathways while leaving the rest of the system intact, it becomes possible to use patterns of dissociations in the performance of behavioral tasks by brain-damaged patients to determine the identity and organization of the functional components of the cognitive system (Shallice, 1988).