Dot enumeration (DE) and number comparison (NC) abilities are considered markers of core number competence. Differences in DE/NC reaction time (RT) signatures are thought to distinguish between typical and atypical number development. Whether a child's DE and NC signatures change or remain stable over time, relative to other developmental…

Arithmetic and cognitive skills of children with mathematical difficulties (MD-only), with comorbid reading difficulties (MD-RD), with reading difficulties (RD-only), and normally achieving children were examined at 3 points from Grades 3-4 to Grades 5-6 (age range, 9-13 years). Both MD groups displayed severe weaknesses in 4 domain-specific…

The factor-analytic history of the isolation and identification of the cognitive ability construct known as Number or Numerical Facility is described. Empirical documentation from the psychometric literature is discussed, and examples of items from a variety of tests which have defined and been associated with the Number factor are included to…