Processing visual contour contributes to the association between numerosity processing and arithmetic performance

Studies have shown that non-symbolic numerosity processing can consistently predict arithmetic performance. Visual form perception has been assumed to be fundamental for both processing, but little empirical evidence has been found for the involvement of visual form perception in numerosity processing and arithmetic performance. The current investigation will examine whether individual dependence on visual properties in numerosity processing can account for substantial variation in arithmetic performance. A total of 6329 participants aged 6 to 87 years old were recruited and divided into nine age groups. The results showed that the total contour/perimeter dominates the numerosity processing for participants in each of the nine age groups. At the individual level, the dependence of total contour/perimeter in numerosity processing indexed by the regression coefficient was larger than the dependence of other visual properties. Importantly, the dependence of total contour/perimeter consistently contributed to the arithmetic performance in each age group. The score for figure matching fully accounted for the contribution of the dependence of total contour/perimeter to arithmetic performance. The findings convergently suggest that the extraction of contour information in dot arrays is fundamental for both numerosity processing and arithmetic performance, which may stem from the shared visual form processing.