Abstract
Neuropsychological and developmental models of number, counting, and arithmetical skills, as well as the supporting working memory and speed of articulation systems, were used as the theoretical framework for comparing groups of low- and average-IQ children. The low-IQ children, in relation to their average-IQ peers, showed an array of deficits, including difficulties in retaining information in working memory while counting, more problem solving errors, shorter memory spans, and slower articulation speeds. At the same time, the low-IQ children's conceptual understanding of counting did not differ from that of their higher-IQ peers. Implications for the relation between IQ and mathematics achievement are discussed.