Based on the stability and level of performance on standard achievement tests in first and second grade (mean age in first grade ϭ 82 months), children with IQ scores in the low-average to high-average range were classified as learning disabled (LD) in mathematics (MD), reading (RD), or both (MD/RD). These children (n ϭ 42), a group of children who showed variable achievement test performance across grades (n ϭ 16), and a control group of academically normal peers (n ϭ 35) were administered a series of experimental and psychometric tasks. The tasks assessed number comprehension and production skills, counting knowledge, arithmetic skills, working memory, the ease of activation of phonetic representations of words and numbers, and spatial abilities. The children with variable achievement test performance did not differ from the academically normal children in any cognitive domain, whereas the children in the LD groups showed specific patterns of cognitive deficit, above and beyond the influence of IQ. Discussion focuses on the similarities and differences across the groups of LD children.

Based on performance on standard achievement tests, first-grade children (mean age ϭ 82 months) with IQ scores in the low-average to high-average range were classified as at risk for a learning disability (LD) in mathematics, reading, or both. These at-risk children (n ϭ 55) and a control group of academically normal peers (n ϭ 35) were administered experimental tasks that assessed number comprehension and production skills, counting knowledge, arithmetic skills, working memory, and ease of retrieving information from long-term memory. Different patterns of intact cognitive functions and deficits were found for children in the different at-risk groups. As a set, performance on the experimental tasks accounted for roughly 50% and 10% of the group differences in mathematics and reading achievement, respectively, above and beyond the influence of IQ. Performance on the experimental tasks thus provides insights into the cognitive deficits underlying different forms of LD, as well as into the sources of individual differences in academic achievement.

A Chinese advantage over Americans was found for economically relevant computational and reasoning abilities in arithmetic for groups of 6th-and 12th-grade students matched or equated on general intelligence. No cross-national difference for computational or reasoning abilities was found for samples of older (60-to 80-year-old)Chinese and American adults equated on general intelligence. The pattern of change in arithmetical competencies across cohorts suggests that the Chinese advantage in 6th and 12th grade is due to a cross-generational decline in competencies in the United States and a crossgenerational improvement in China.

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.

Dual process theory postulates two representational processes: Activation of a representation makes the mental event more easily and automatically accessible. Elaboration of a mental event produces access to the representation through search and retrieval processes. We explored word priming in recognition and in a stem completion task where the primed word was one of several possible completions for a 3-letter stem. The main hypothesis was that priming has similar and parallel effects in the two tasks. The initial presentation (priming) of items was under conditions of either semantic or non-semantic processing. Priming was either direct, by the presentation of the target word, or indirect, by the presentation of phonologically related (rhyming) or semantically related (categorical) items. When priming occurred, RTs increased from direct to phonologically primed and to semantically primed items for both completion and recognition tests. One additional experiment confirmed the absence of semantic processing in the non-semantic condition, and another experiment showed that when response requirements for recognition and completion responses are equated, RTs to the two tests are comparable.