Processing speed links approximate number system and arithmetic abilities

Mechanisms underlying the correlation between approximate number system (ANS) and arithmetic abilities remain unclear. We hypothesized that processing speed can explain this correlation. This correlation was significant only when the dot arrays were displayed for 200 ms, but not when they were presented until response, implying the importance of processing speed (Study 1). To examine the role of processing speed, 120 adults completed dot comparison (display time, 200 ms), arithmetic, two processing speed (inspection time and choice reaction time), and control tasks (Study 2). We observed a significant correlation between ANS and arithmetic performance. However, it disappeared after controlling for processing speed. Inspection time accounted for the correlation between the accuracies of the dot comparison and arithmetic tasks, while choice reaction time accounted for the correlation between the reaction times of the two tasks. Overall, processing speed can be an alternative mechanism for the correlation between ANS and arithmetic abilities.