Neurocognitive mechanisms of mathematics vocabulary processing in L1 and L2 in South African first graders: a functional near-infrared spectroscopy study.

SIGNIFICANCE: To learn mathematics, young children require accurate interpretations of mathematics vocabulary. When school language differs from children's home language, mathematics performance often decreases. Little is known about cortical activation during mathematics vocabulary processing in different languages. Although behavioral data highlight a difference in L1 and L2 mathematics learning, neuroimaging insights will help us to better understand how and why there is a difference in children's mathematical learning in multilingual societies.

AIM AND APPROACH: We investigated behavioral and brain responses (fNIRS) of 42 isiZulu and Sesotho (L1) first graders (6.75 to 7.83 years, 22 girls) who learn mathematics in English (L2) at school when they encounter mathematics vocabulary in L2 compared with L1 and mathematics vocabulary compared with object recognition in L1.

RESULTS: The results show that higher accuracy in the L1 mathematics vocabulary, as compared with the L2 mathematics vocabulary, comes with the costs of higher cognitive demands in the right superior and middle frontal gyri for first graders. Mathematics vocabulary required longer response time than object recognition and a higher activation in the right superior frontal gyrus. No parietal difference was observed between conditions.

CONCLUSIONS: Neuroimaging revealed that children engaged additional frontoparietal regions when processing L1 mathematics vocabulary-patterns not detectable through behavioral measures alone. Increased frontal activation suggests that the interpretation of mathematics vocabulary in L2 is not yet automatized. This study demonstrates how educational neuroimaging refines interpretations of behavioral outcomes within multilingual contexts.