The development of early numeracy ability in kindergartners with limited working memory skills

•939 children were twice screened on working memory; a high overlap emerged.•Majority of children with limited working memory struggled in all numeracy domains.•Distinction is made between limited capacity in verbal and in visual working memory.•No clear differences in numeracy for verbal vs. visual limited working memory.•Visual early numeracy skills seem to be most important in number line estimation.

Research has proven limited working memory skills to be a high risk factor for educational underachievement in mathematics across the primary school years. Less is known, however, about the performance of children with limited working memory skills in early numeracy tasks. The main purpose of the two studies reported in this article is to explore the difficulties these children experience in performing early numeracy tasks. In both studies, children with very low working memory skills were identified from a large sample (N = 939), in order to examine in which early numeracy domains they lag behind (Study 1,2) or develop more slowly (Study 1) than their typically developing peers. Results show weaknesses in almost all domains of early numeracy (Study 1) but, against expectations, no pattern in early numeracy could be seen that distinguishes children with problems in verbal working memory from children with problems in visual working memory (Study 2).