Age of acquisition and lexical processing in Aphasia: A case study

Abstract

This paper presents a single-case study of an aphasic patient, NP, whose lexical processing was affected by age of acquisition, such that words typically acquired early in life were processed with greater accuracy in spoken naming, written naming, and reading aloud than were later-acquired words. A combination of multiple regression and factorial designs was used in an effort to establish that age of acquisition, rather than word frequency or imageability (both factors with which age of acquisition is highly correlated), influenced success in speech production tasks. In addition to showing effects of age of acquisition on spoken naming, written naming, and reading aloud, NP also showed evidence of both semantic and phonological impairments. On the basis of NP's pattern of impairments and studies of the effects of age of acquisition on lexical processing in normal subjects, we propose that age of acquisition affects the process of retrieving phonological word-forms, with early-acquired phonological representations being more robust and less vulnerable to brain injury than are later-acquired representations.