The relation of verbal and nonverbal skills to basic numerical processing of preterm versus term-born preschoolers.

Verbal and nonverbal skills significantly contribute to individual differences in children's numerical development at the group level. However, less is known about whether the nature of the relations between verbal and nonverbal systems and numerical cognition varies depending on the unique characteristics children bring into numerical learning. To better delineate these associations, we examined the association between verbal and nonverbal skills and symbolic numerical development in preterm-born (PTB; n = 93; <37 weeks of gestation) children and term-born children (n = 104). We showed that PTB preschoolers, as a group, were at a higher risk of falling behind on certain numerical tasks (cardinality) but not on others (counting). There was, however, significant individual variability within the groups. Verbal and nonverbal skills contributed to the variability of children's numerical performance but did so differentially across the full spectrum of gestational age. Specifically, verbal skills moderated the association between gestational age and symbolic number performance (cardinality). The relation between verbal and cardinality skills was stronger at higher gestational ages compared with lower gestational ages. In addition, at higher gestational ages, children more frequently used retrieval strategy and less often relied solely on finger counting for the cardinality task. Shifting the focus from group differences to understanding individuals and their unique developmental pathways may enhance our insight into the risk and protective factors underlying the variability observed in all children.