LEXICAL ACCESS IN APHASIC AND NONAPHASIC SPEAKERS

An interactive 2-step theory of lexical retrieval was applied to the p icture-naming error patterns of aphasic and nonaphasic speakers. The t heory uses spreading activation in a lexical network to accomplish the mapping between the conceptual representation of an object and the ph onological form of the word naming the object. A model developed from the theory was parameterized to fit normal error patterns. It was then ''lesioned'' by globally altering its connection weight, decay rates, or both to provide fits to the error patterns of 21 fluent aphasic pa tients. These fits were then used to derive predictions about the infl uence of syntactic categories on patient errors, the effect of phonolo gy on semantic errors, error patterns after recovery, and patient perf ormance on a single-word repetition task. The predictions were confirm ed. It is argued that simple quantitative alterations to a normal proc essing model can explain much of the variety among patient patterns in naming.