Forty-five children with mathematics learning disabilities, with and without comorbid reading disabilities, were compared to 45 normally achieving peers in tasks assessing basic numerical skills. Children with mathematics disabilities were only impaired when comparing Arabic digits (i.e., symbolic number magnitude) but not when comparing…

This paper examines what children believe about unmapped number words--those number words whose exact meanings children have not yet learned. In Study one, 31 children (ages 2-10 to 4-2) judged that the application of "five" and "six" changes when numerosity changes, although they did not know that equal sets must have the same number word. In…

Recent work suggests that infants rely on mechanisms of object-based attention and short-term memory to represent small numbers of objects. Such work shows that infants discriminate arrays containing 1, 2, or 3 objects, but fail with arrays greater than 3 [Feigenson, L., & Carey, S. (2003). Tracking individuals via object-files: Evidence from…

Developmental research suggests that some of the mechanisms that underlie numerical cognition are present and functional in human infancy. To investigate these mechanisms and their developmental course, psychologists have turned to behavioral and electrophysiological methods using briefly presented displays. These methods, however, depend on the…

This brief report attempts to resolve the claim that infants preferentially attend to continuous variables over number [e.g. Psychol. Sci. 10 (1999) 408; Cognit. Psychol.44 (2002) 33] with the finding that when continuous variables are controlled, infants as young as 6-months of age discriminate large numerical values [e.g. Psychol. Sci. 14 (2003)…

Examined analog number representations in 5- to 7- year-olds. Found that subjects accurately estimated rapidly presented groups of 5 to 11 items. Children's data were qualitatively and to some degree quantitatively similar to adult data, with one exception. The ratio of the standard deviation of estimates to mean estimates decreased with age.…

Examined the nature of numerical knowledge in 5-month-olds to inform the debate whether numerical abilities result from capacities dedicated to numerical cognition or to more general perceptual capacities. Found that 5-month-olds could determine the number of collective entities, moving groups of items, when non-numerical perceptual factors such…

Two experiments examined preschoolers' performance on test relying on the uniqueness principle for using evidence from a miscount in inferring a counterfactual cardinal number, with subtests probing associated number-skills. All the 5-year-olds and half the preschoolers passed the test. Results suggest that a crucial preschool step is to start…

Two experiments examined development of the ordinality concept in infants. Found that 11-month-olds successfully discriminated, whereas 9-month-olds failed to discriminate sequences that descended in numerical value from sequences increasing in numerical value. Nine-month-olds could discriminate the ordinal direction of sequences that varied in…