In an article published on the Learning Counsel, Betsy Hill and Roger Stark write:
While reading difficulties have been studied extensively in the last few decades, difficulties learning math have received less attention. Math disabilities, however, are as common as reading disabilities at 5 to 8 percent of the population. Like reading disabilities, math disabilities may have multiple causes and dimensions. Moreover, as the math curriculum has changed over the last ten to fifteen years, more emphasis has been placed on communicating math ideas, interpreting data from charts and figures, and estimating. These changes mean that learning deficits in any area are more likely to impact performance in math. In fact, many individuals with a math disability also have learning disabilities in other areas. Whether or not other learning disabilities are present, however, there is growing evidence that underlying cognitive processes play a significant role in math performance.
Geary describes the relationship between various cognitive mechanisms and deficits in math ability which may be summarized in the following chart:
|Cognitive mechanisms||Math deficit|
|Language systems||Information representation, as in articulating number words|
|Working Memory||Information manipulation as during the act of counting.|
|Visual-spatial processing||Representations of conceptual knowledge, such as number magnitudes and information in a spatial form (as in a chart)|
|Attentional and inhibitory processes (executive controls)||Using procedures during problem solving|
Based on an analysis of the mechanisms and related types of math deficits for which there is empirical support, Geary defines three subtypes of math disability: Semantic Memory, Procedural and Visual- Spatial. The following discussion provides an overview of the three subtypes, the deficits associated with them and the underlying cognitive skills impairing effective performance.