An exaggerated effect for proper nouns in a case of superior written over spoken word production

Abstract

We describe a brain-damaged subject, RR, who manifests superior written over spoken naming of concrete entities from a wide range of conceptual domains. His spoken naming difficulties are due primarily to an impairment of lexical-phonological processing, which implies that his successful written naming does not depend on prior access to the sound structures of words. His performance therefore provides further support for the “orthographic autonomy hypothesis,” which maintains that written word production is not obligatorily mediated by phonological knowledge. The case of RR is especially interesting, however, because for him the dissociation between impaired spoken naming and relatively preserved written naming is significantly greater for two categories of unique concrete entities that are lexicalised as proper nouns—specifically, famous faces and famous landmarks—than for five categories of nonunique (i.e., basic level) concrete entities that are lexicalised as common nouns—specifically, animals, fruits/vegetables, tools/utensils, musical instruments, and vehicles. Furthermore, RR's predominant error types in the oral modality are different for the two types of stimuli: omissions for unique entities vs. semantic errors for nonunique entities. We consider two alternative explanations for RR's extreme difficulty in producing the spoken forms of proper nouns: (1) a disconnection between the meanings of proper nouns and the corresponding word nodes in the phonological output lexicon; or (2) damage to the word nodes themselves. We argue that RR's combined behavioural and lesion data do not clearly adjudicate between the two explanations, but that they favour the first explanation over the second.