The impact of developmental dyslexia and dysgraphia on movement production during word writing.

This study investigated how deficits in orthographic processing affect movement production during word writing. Children with dyslexia and dysgraphia wrote words and pseudo-words on a digitizer. The words were orthographically regular and irregular of varying frequency. The group analysis revealed that writing irregular words and pseudo-words increased movement duration and dysfluency. This indicates that the spelling processes were active while the children were writing the words. The impact of these spelling processes was stronger for the children with dyslexia and dysgraphia. The analysis of individual performance revealed that most dyslexic/dysgraphic children presented similar writing patterns. However, selective lexical processing deficits affected irregular word writing but not pseudo-word writing. Selective poor sublexical processing affected pseudo-word writing more than irregular word writing. This study suggests that the interaction between orthographic and motor processing constitutes an important cognitive load that may disrupt the graphic outcome of the children with dyslexia/dysgraphia.