Demonstrating a wordlikeness effect on nonword repetition performance in a conduction aphasic patient q Akie Saito, a, * Takako Yoshimura, b Tohru Itakura, c and Matthew A. Lambon Ralph d a Department of Cognitive Psychology in Education, Graduate School of Education, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan b Graduate School of Integrated Studies in Language and Society, Osaka University of Foreign Studies, Osaka, Japan c Department of Neurological Surgery, Wakayama Medical College, Wakayama, Japan d Department of Psychology, University of Manchester, Manchester, UK Accepted 11 October 2002 Abstract The purpose of this study was to identify the nature of the deficit for a conduction aphasic patient in order to evaluate two different theories of conduction aphasia. First, a conduction aphasic patient FS was tested on auditory word-pair discrimination, word-repetition, and picture-naming. The results of these tasks indicated that her deficit was likely to be post-lexical rather than perceptual or lexical. Next, we examined her repetition performance for two types of nonwords (high-wordlike and low-wordlike nonwords) to distinguish the two theories. FS exhibited a wordlikeness effect: she produced more correct moras and more correct combinations of moras for high-wordlike nonwords than low-wordlike nonwords. We conclude that she had difficulty in main- taining stable phonological representations of verbal materials in the output buffer. Ó 2002 Elsevier Science (USA). All rights reserved. 1. Introduction Conduction aphasia is characterized by impaired repetition combined with relatively intact auditory comprehension. Another symptom of this aphasia is the production of sublexical errors (phonemic paraphasias) across different tasks that measure output ability (e.g., picture naming and word repetition: Caplan, 1992; Kohn,1989).Sublexicalerrorsinvolveaddition,deletion, substitution, and misordering of segments. Substitution errors occur when the target segment is replaced by an adjacent one (e.g., Crete ! [krik]) or by a contextually unrelated sound. Order errors happen when two target segments exchange their place within or between the words (e.g., degree ! [gcdriz]—from Blumstein, 1990). Within standard models of speech production, sub- lexical errors in conduction aphasia arise from a deficit at the post-lexical or phonological-encoding stage in speech production (e.g., Kohn, 1984; Pate, Saffran, & Martin, 1987; see Fig. 1). At this stage, the phonological representation of the intended word that has been re- trieved from the phonological lexicon is temporarily stored in an output buffer and each segment in the word is placed in the correct position. Three lines of evidence suggest that the critical impairment occurs at the post- lexical stage and not at the lexical retrieval stage. First, conduction aphasic patients tend to show per- formance on picture naming that is qualitatively similar to that on other word production tasks (e.g., Caplan, 1992; Kohn, 1989; Shallice, Rumiati, & Zadini, 2000; Wilshire & McCarthy, 1996). Word production tasks such as repetition or reading depend relatively less on the lexicon than naming does because the surface form of the target word activates sublexical phonology di- rectly. Naming, however, involves the retrieval of the target wordÕs phonological representation, implying that naming performance should be directly affected by a retrieval deficit. On the other hand, when the deficit is in the post-lexical stage, naming performance should not differ greatly from word reading or repetition perfor- mance (Nickels, 1997). Brain and Language 85 (2003) 222–230 www.elsevier.com/locate/b&l q Wethankouranonymousreviewersfortheirhelpfulcommenton a previous version of this paper. * Corresponding author. Fax: +81-75-753-3025. E-mail address: m53795@sakura.kudpc.kyoto-u.ac.jp (A. Saito). 0093-934X/02/$ - see front matter Ó 2002 Elsevier Science (USA). All rights reserved. doi:10.1016/S0093-934X(02)00589-8