Individual differences modulate the neural correlates of fraction processing in primary-school children in South Africa

Fractions are one of the most challenging concepts in primary school mathematics. While there is a substantial number of behavioural studies on fraction calculation in primary school children, our understanding of the underlying neural mechanisms is limited. This knowledge is crucial for improving teaching strategies. Moreover, few neuroimaging studies on fraction calculation have been conducted in Western, Educated, Industrialised, Rich, and Democratic (WEIRD) populations, even though environmental factors play a pivotal role in human cognitive development. The current study investigated the neural correlates of the complexity of fraction calculation and how individual differences modulate these processes. Two groups of fifth graders with low and high competence in fractions completed simple and complex fraction problems while their brain responses were recorded using functional near-infrared spectroscopy (fNIRS) in an ecologically valid setting. In a fraction comparison task, fifth graders had to identify which of the two visually presented fractions was larger. Fraction complexity led to increased activation in the right dorsomedial frontal region in the high-competence group but not in the low-competence group. This finding suggests that only the high-competence group recruited frontal cognitive resources, as evidenced by their higher behavioural performance. To the best of our knowledge, this is the first educational neuroscientific study of mathematical cognition in sub-Saharan countries and the first neuroimaging study of individual differences in fractions. This research will shed light on less-studied populations and contribute to our understanding of the neural mechanisms involved in fraction calculation.