Specific order impairment in arabic number writing: A case-study.

The present study examines the transitory deficit in transcoding verbal to Arabic numbers in an aphasic patient, TM. She showed a mild syntactic impairment in syntactic comprehension of verbal numbers, with preserved performance in comprehension of Arabic numbers, in access to semantic representation, as well as in reading of Arabic numbers, but she committed 75% of errors when required to write numbers in the Arabic format to dictation. In conformity to the previous literature on transcoding deficits, the majority of her errors were syntactic (60%). However, most of them were unusual "order errors" (50%) in which lexical digits (e.g., 1 to 9) were written on the left and zeros on the right of the number, which contained in the majority of the cases the correct number of digits. A similar type of errors has been reported in only one previous case study (Delazer & Denes, 1998), but not specifically studied. We discuss hypotheses concerning its origins as stemming from a syntactic disorder within existing models of transcoding (McCloskey, Caramazza, & Basili, 1985; Power & Dal Martello, 1990). We also report kinematic assessment of the patient's handwriting before and after recovery. At time of the second examination, results show that her pattern of movement fluency parallels that of healthy subjects and supports a distinction between two types of zeros within Arabic numbers, in relation to the verbal code and the rules required to produce them. This paper thus also highlights the potential usefulness of using a digitising tablet in the study of transcoding deficits.