Motor speech control and cluttering: David Ward
A recurring theme throughout this book concerns the not inconsiderable diﬃculty in deciding exactly what cluttering is. Particularly, arriving at a deﬁnition that is suitably succinct, but that captures the breadth of the core symptoms and how these might be expressed, remains problematic. Weiss (1964) famously considered cluttering to be just one facet of a bigger syndrome, aﬀecting attention and memory as well speech and language functions. It was, he argued, the verbal manifestation of a ‘central language imbalance’. Despite the wide range of speech and non-speech phenomena that Weiss associated with the disorder, one consistently observed feature is that speech output in cluttering appears to be motorically disrupted. Since this, a number of deﬁnitions have been proposed, most recently St. Louis and Schulte’s lowest common denominator model (St. Louis & Shulte, chapter 14 this volume), yet through the diﬀerences of opinion that have persisted in the intervening 45 years, there has been common agreement that cluttering is expressed by an output that sounds motorically disrupted. The key features of inconsistent pacing (and usually fast sounding) speech output, short inappropriately placed pauses, and over co-articulation, all implicate motor speech processing in some shape or form (Daly & Cantrell, 2006; St. Louis & Shulte, chapter 14 this volume; Ward, 2006).