THE INDEPENDENCE OF PHONOLOGICAL AND ORTHOGRAPHIC LEXICAL FORMS - EVIDENCE FROM APHASIA

WMA suffers from damage to the semantic component of the lexical seman tic system and from damage to sublexical phonology-orthography and ort hography-phonology conversion procedures. His performance on picture n aming tasks that require two consecutive responses was used to explore issues concerning the relations between the phonological and orthogra phic components of the lexical system. Responses to tasks requiring re sponses in different modalities (one oral and one written) often resul ted in lexically ''inconsistent'' responses. For example, to a picture representing pliers, WMA said ''pincers,'' but wrote saw,; and, to a picture representing peppers, he wrote tomato but said ''artichoke.'' By contrast, inconsistent responses never occurred in tasks that requi red two consecutive responses in the same modality (oral or written). In these tasks, WMA always produced the same (correct or incorrect) wo rd twice. These results rule out the hypothesis that phonological medi ation is necessary for writing, and suggest instead that orthographic word forms are autonomous from phonological forms, and that they are a ctivated directly from lexical semantic information. However, the resu lts do not allow us to distinguish between a weak version of the ortho graphic autonomy hypothesis-that there are direct connections between phonological and orthographic forms, which are impaired in WMA-and a s trong version of the same hypothesis-that phonological and orthographi c word forms are completely autonomous but that the selection of a wor d form for output in a given modality can be constrained by sublexical conversion mechanisms, which are impaired in WMA.