From birth, humans are able to discriminate quantities using the approximate number system (ANS). However, previous methods have only been suitable to examine ANS functioning in infancy and older children. The goals of this study were twofold: first, to modify an existing method of assessing ANS functioning for toddlerhood; and second, to investigate individual differences in toddlers' ANS performance by examining correlations with their parents' ANS acuity. Using a preferential looking paradigm, we found that 1-to 3-year-olds (N=46) looked significantly longer to numerically changing images compared to numerically constant ones suggesting that the paradigm is a suitable measure of ANS functioning in toddlerhood. Furthermore, we found a positive relation between toddlers' ANS performance and that of their parents (assessed using a non-symbolic number comparison task) independent of children's vocabulary or parents' perceived math ability or preference for math. These findings are consistent with a specific intergenerational transmission of the ANS.

Several studies suggest that parents' use of number words while talking with their children is positively related to children's understanding of certain mathematical concepts. In this study, we extended these findings and further examined several parent characteristics that could be related to individual differences in their number talk, including their subjective ratings of their math skills, preference for using math, beliefs about the importance of their children's math skills, and numerical approximation abilities, an early number skill present in children and adults. A sample of 44 5- and 6 -year-old children and their parents completed a variety of laboratory-based tasks, including a 10-min free play session to assess number talk, a standardized math assessment for children, a nonsymbolic numerical comparison task for parents, and several questionnaires for parents. Parents' overall number talk was not related to children's performance on the math assessment; however, parents' use of numbers larger than 10 was positively and significantly related to children's math abilities even when controlling for parents' overall talk. Parents' large number talk was also associated with their numerical approximation abilities and subjective math ability, suggesting that math-specific characteristics of parents themselves can explain some of the individual variability in parents' use of number words, especially those larger than 10. (C) 2017 Elsevier Inc. All rights reserved.