Developmental graphemic buffer dysgraphia in English: A single case study.

A single case study is reported of a 10-year-old, English-speaking boy, L.S., who presented with spelling errors similar to those described in acquired graphemic buffer dysgraphia (GBD). We used this case to evaluate the appropriateness of applying adult cognitive models to the investigation of developmental cognitive disorders. The dual-route model of spelling guided this investigation. L.S. primarily made "letter errors" (deletions, additions, substitutions, transpositions, or a combination of these errors) on words and nonwords and in all input (aural and visual) and output modalities (writing, typing, oral spelling); there was also some evidence of a length effect and U-shaped serial position curve. An effect of lexical variables on spelling performance was also found. We conclude that the most parsimonious account is an impairment at the level of the graphemic buffer and without systematic cognitive neuropsychological investigation, the nature of L.S.'s spelling difficulty would likely have been missed.