Mathematical skills in heritage bilingual children with and without developmental dyscalculia: A comparative study

This study examined how basic numeracy skills relevant for identifying developmental dyscalculia (DD) differ between heritage bilingual (HB) children and monolingual peers, given the wellestablished links between language experience and numerical cognition. We compared sociolinguistic background, cognitive abilities, and mathematical performance in 311 primary school children, divided into four groups: HBs with a Specific Learning Disorder in mathematics (SLDDD; n = 72), HBs with typical development (TD; n = 86), monolinguals with SLD-DD (n = 56), and monolinguals with TD (n = 97). Parents provided detailed language-history information, and children completed standardized assessments of nonverbal IQ, working memory, processing speed, and mathematical skills across numerical knowledge, calculation, and number sense. Controlling for socioeconomic status (SES) and listening comprehension as a proxy for L2 proficiency, results showed that HB children with SLD-DD exhibited numeracy difficulties comparable to monolinguals with SLD-DD but performed better in number-sense tasks, particularly in the triplets task, suggesting a possible bilingual advantage in this domain. HB children with SLDDD also displayed greater dominance in Italian than typically developing HBs, who showed a more balanced bilingual profile. Among typically developing children, HBs underperformed monolingual peers on linguistically demanding tasks but performed similarly on tasks with limited verbal load. SES was related only to nonverbal cognitive functioning, whereas listening comprehension significantly covaried with all verbally mediated tasks. Overall, the findings underscore the importance of considering both SES and L2 language skills when assessing mathematical performance in bilingual learners and highlight the need for targeted support in language-heavy mathematical contexts.