ABSTRACT
The breadth and complexity of the field of mathematics make the identification and study of the cognitive phenotypes that define learning disabilities in mathematics (MD) a formidable endeavor. A learning disability can result from deficits in the ability to represent or process information in one or all of the many mathematical domains (e.g., geometry) or in one or a set of individual competencies within each domain. The goal is further complicated by the task of distinguishing poor achievement due to inadequate instruction from poor achievement due to an actual cognitive disability (Geary, Brown, & Samaranayake, 1991). One approach that can be used to circumvent this assessment confound is to apply the theories and methods used to study mathematical competencies in normal children to the study of children with MD (Bull & Johnston, 1997; Garnett & Fleischner, 1983; Geary & Brown, 1991; Geary, Widaman, Little, & Cormier, 1987; Jordan, Levine, & Huttenlocher, 1995; Jordan, Hanich, & Kaplan, 2003a; Jordan & Montani, 1997; Ostad, 1997, 1998a; Russell & Ginsburg, 1984; Svenson & Broquist, 1975). When this approach is combined with studies of dyscalculia, that is, numerical and arithmetical deficits following overt brain injury (Shalev, Manor, & Gross-Tsur, 1993; Temple, 1991), and brain-imaging studies of mathematical processing (Dehaene, Spelke, Pinel, Stanescu, & Tsivkin, 1999), a picture of the cognitive and brain systems that can contribute to MD begins to emerge.
