Towards a unified process model for graphemic buffer disorder and deep dysgraphia

Models based on the competitive queuing (CQ) approach can explain many of the effects ondysgraphic patients’ spelling attributed to disruption of the “graphemic output buffer”. Situatingsuch a model in the wider spelling system, however, raises the question of what happens wheninput to the buffer (e.g., from a semantic system) is degraded while the buffer remains intact. Wepresent a preliminary exploration of predictions following from the CQ approach. We show thatthe CQ account of the graphemic buffer predicts and explains the finding that deep dysgraphicpatients generally show features of graphemic buffer disorder, as disrupted input from a damagedsemantic system has an inevitable effect upon the functioning of the buffer. The approach also explainsthe most salient differences between the two syndromes, which are seen as consequences of the differ-ence between an intact sequence generation system operating on degraded input versus a damagedsequencing system operating on intact input.