ABSTRACT
Evidence from double dissociations between aspects of reading and writing in Japanese dyslexic and dysgraphic patients, as well as between the various languages of polyglot aphasic patients, is interpreted as supportive of the hypothesis that cognitive processing is fractionable into subcomponents, themselves fractionable into sub-subcomponent modules. The demonstrated double-dissociative inhibition of various aspects of language processing is taken as evidence of their neurofunctional modularity. More specifically, it is argued that the faculty of language fractions into as many vertical subsystems as there are languages represented in the patient's brain, that within each language subsystem reading and writing are isolable modular subsubsystems, and that there are as many such modular subsubsystems as there are orthographies involved.
