Cognitive Addition: A Short Longitudinal Study of Strategy Choice and Speed-of-Processing Differences in Normal and Mathematically Disabled Children

This study provided a longitudinal assessment of skill development in addition for 26 normal and 12 mathematically disabled firstor second-grade children. At the first time of measurement, the children solved 40 simple addition problems. Ten months later, all subjects were readministered the addition task and a measure of working memory resources. Across times of measurement, the normal group showed increased reliance on memory retrieval and decreased reliance on counting to solve the addition problems, as well as an increase in speed of counting and of retrieving addition facts from long-term memory. The math-disabled group showed no reliable change in the mix of problem-solving strategies or in the rate of executing the counting or memory retrieval strategies. Finally, reliable differences, favoring the normal group, were found for the index of working memory resources.