A Linguistic Approach to Language Processing in Broca's Aphasia: A Paradox Resolved

Abstract

Linguistic interest in aphasia is partially due to the fact that focal in juries to different parts of the brain not only lead to selective cognitive disorders, but may also lead to dam age of distinct components of lan guage or of specific linguistic processing mechanisms. Thus, aphasie deficits following brain damage can serve as a testing ground for theoretical models of the normal mental grammar. In addi tion, linguistic theories of grammar have been utilized in the attempt to provide an explanation for the defi cits that occur on the grounds that aphasie language can be understood only in relation to the normal, intact brain and mental grammar. The speech of patients who have focal lesions in Broca's area is often characterized as agrammatic be cause many of the grammatical or function words are missing from their sparse and labored speech pro duction. The comprehension of many of these patients has interested linguistic aphasiologists because it too has often been characterized as agrammatic or asyntactic. Specifi cally, the comprehension of these patients is at chance for sentences just when correct interpretation of a sentence depends on a proper ap preciation of its syntactic structure. However, the same kinds of sen tences that are difficult to compre hend pose little difficulty for these patients when they are asked to make meta-linguistic judgments about sentences' grammatical ac ceptability. The fact that they can accurately distinguish welland in formed instances of the very same sentence constructions that reduce them to guessing in comprehension tasks is perplexing because it seems to entail the paradox that these indi viduals' syntactic processing is both damaged and undamaged at exactly the same points! In short, their syn tax is there but not there.