Does numerical processing uniquely predict first graders' future development of single-digit arithmetic?

The present longitudinal study investigated whether children's numerical processing skills at the start of formal schooling predict subsequent development in single-digit arithmetic and fact retrieval. At the start of first grade, we administered measures of numerical processing (digit naming, symbolic numerical magnitude comparison, nonsymbolic numerical magnitude comparison) as well as measures of intellectual ability, preschool mathematical abilities, working memory and processing speed. Our longitudinal data indicate that children's numerical processing skills at primary school entrance were predictively related to their future competence in single-digit arithmetic and their reliance on arithmetic fact retrieval. This association was not explained by children's intellectual ability, preschool mathematical abilities, verbal working memory, visual-spatial short-term memory and processing speed. These findings indicate that numerical processing skills precede children's development in single-digit arithmetic.