ABSTRACT
This chapter examines patterns of impaired performance in light of a detailed and explicit model of the normal number-processing and calculation systems. It suggests that the cognitive mechanisms for number comprehension are distinct from those for number production. The chapter shows that impaired performance reflects damage to a cognitive system that was, prior to the damage, capable of performing the task successfully. The process of interpreting and classifying deficits necessarily involves assumptions about normal processing—impaired performance is interpreted in terms of damage to one or more components of a normal cognitive system. In the first place, a well-articulated theory of normal and impaired cognitive processing is essential in any attempt to relate cognitive processes to brain mechanisms, whether in the realm of number processing or in any other cognitive domain. Syntactic processing, in contrast, involves the processing of relations among elements in order to comprehend or produce a number as a whole.
