Spatially specific deficits in processing graphemic representations in reading and writing.

We report the performance of two brain-damaged subjects, HB and ML, whose spelling performance is characterized by selective impairment in processing the side of words contralateral to their brain damage. A striking feature of these patients' performance was the fact that their spelling errors in all tasks--written naming, written and oral spelling, and delayed copy transcription--almost exclusively concerned the right half of words (in the case of HB) or the left half of words (in the case of ML), regardless of length of the target response. These patterns of performance are interpreted as indicating damage at the level of the grapheme description computed in all spelling tasks. We also discuss the additional observations that HB tended to complete words with nonrandom letter sequences in misspelling the final half of the word and that ML tended to preserve the initial letter of the word (in forward but not backward spelling) even when she made errors on other letters in the initial half of the word. Finally, the relationship between these spatially specific impairments of reading and writing and their relationship to spatially specific deficits in non-lexical tasks is reviewed.