Afferent dysgraphia and the role of vision in handwriting

Afferent dysgraphia is an acquired writing deficit characterized by deletio ns and duplications of letters and strokes. The commonly accepted interpret ation is that patients do not use visual and kinaesthetic input. In this pa per, we describe a woman who, following right brain damage, made errors alm ost exclusively involving letters with repeated strokes. She was normal at a kinaesthetic recognition task and, like the control subjects, produced mo re errors when blindfolded. We conclude that afferent dysgraphia does not r esult neither from an impairment of vision and kinaesthesis, or from an att entional deficit. Rather, it results from a defective mechanism, specific t o handwriting, which computes afferent information to keep track of positio n in letter and stroke sequences.