Neural correlates of fraction magnitude processing in high and low achieving primary school children in South Africa

Fractions are one of the most challenging concepts in primary school mathematics. While there are many behavioural studies on fraction calculation in primary school children, our understanding of the underlying neural mechanisms remains limited. This knowledge will help shed light on learning variability among children. Furthermore, few neuroimaging studies on fraction calculation have been conducted in Western, Educated, Industrialised, Rich, and Democratic (WEIRD) populations, despite environmental factors playing a crucial role in human cognitive development. The current study examined the neural correlates of the complexity of fraction comparison and how individual differences influence these processes in 39 12-year-old children in South Africa. Two groups of fifth graders with low and high performance in fractions completed simple and complex fraction comparisons 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. The complexity of the fractions led to increased activation in the right dorsomedial frontal region in high performers but not in low performers. This finding suggests that frontal cognitive resources were engaged only in high performers, as shown 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.