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Knowledge and skill in multiplication were investigated for late elementary-grade students with mathematics learning disabilities (MLD), typically achieving age-matched peers, low-achieving age-matched peers, and ability-matched peers by examining multiple measures of computational skill, working memory, and conceptual knowledge. Poor multiplication fact mastery and calculation fluency and general working memory discriminated children with MLD from typically achieving age-matched peers. Furthermore, children with MLD were slower in executing backup procedures than typically achieving age-matched peers. The performance of children with MLD on multiple measures of multiplication skill and knowledge was most similar to that of ability-matched younger children. MLD may be due to difficulties in computational skills and working memory. Implications for the diagnosis and remediation of MLD are discussed.
Keywords: mathematics learning disabilities; multiplication; computational skill; conceptual understanding; dyscalculia; working memory
Mathematics learning disabilities (MLD) or developmental dyscalculia is a cognitive disorder impairing the typical acquisition of arithmetic skills (Ardila & Rosselli, 2002). It is diagnosed when a child's mathematical achievement, as measured by individually administered standardized tests, is substantially below what is expected based on their intelligence and education (American Psychiatric Association, 1994). MLD is estimated to affect 5% to 8% of school-age children (Geary, 2004; Gross-Tsur, Manor, & Shalev, 1996) and is thus as prevalent as reading disabilities. Despite this similar incidence, substantially less effort has been directed at understanding the cognitive impairments associated with MLD than reading disabilities (Gersten, Jordan, & Flojo, 2005; Jordan, Levine, & Huttenlocher, 1995). Advances in detection, remediation, and understanding of the neural basis of reading disabilities have occurred because researchers have discovered core cognitive deficits that impair the acquisition of literacy skills, including poor phonological processing (Lovett, Lacerenza, & Borden, 2000; Lovett, Steinbach, & Frijters, 2000; B. A. Shaywitz et al., 2004; S. E. Shaywitz et al., 2003). Similarly, the identification of the core difficulties that discriminate children with MLD from their peers is essential for understanding and addressing problems in mathematics cognition (Gersten et al., 2005). Understanding impairments in MLD also informs the examination of the many neurodevelopmental disorders that implicate mathematics, including Turner syndrome (Kesler, Menon, & Reiss, 2005; Mazzocco, 2001), fragile X syndrome (Mazzocco, 2001), nonverbal learning disability (Rourke, 1989), spina bifida (Dennis & Barnes, 2002), hydrocephalus (Barnes et al., 2002), low birth weight...