Lexical access in aphasic and nonaphasic speakers.

TLDR

The theory employs spreading activation in a lexical network to map conceptual representations of objects to their phonological forms. The study aimed to use model fits to predict how syntactic categories, phonology, recovery, and repetition tasks influence aphasic patient errors. The authors applied an interactive two‑step lexical retrieval theory, parameterized it to normal error patterns, and then lesioned it by altering connection weights and decay rates to fit the error patterns of 21 fluent aphasic patients. The predictions were confirmed, and the authors argue that simple quantitative changes to a normal processing model explain much of the naming error variability among patients.

Abstract

An interactive 2-step theory of lexical retrieval was applied to the picture-naming error patterns of aphasic and nonaphasic speakers. The theory uses spreading activation in a lexical network to accomplish the mapping between the conceptual representation of an object and the phonological 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 patients. These fits were then used to derive predictions about the influence of syntactic categories on patient errors, the effect of phonology on semantic errors, error patterns after recovery, and patient performance on a single-word repetition task. The predictions were confirmed. It is argued that simple quantitative alterations to a normal processing model can explain much of the variety among patient patterns in naming.