Age modulates the relation between number-space associations and arithmetical abilities in elementary school children

Evidence for number-space associations comes from the SNARC effect, consisting in faster RTs to small/large digits with the left/right hand respectively. In adults, number-space associations relate to mathematical proficiency in that individuals with weaker arithmetic performances feature stronger SNARC effects (Hoffmann et al., 2014). However, in children far less is known about number-space associations and how they affect arithmetic performance. We therefore investigated the relationship between the classical parity SNARC effect and mathematical proficiency, assessed using the Heidelberger Rechentest, in elementary school children aged 8-11 years (n=55, mean=9.5). Overall, the parity SNARC regression slopes (-11.37, p<.001) negatively correlated with HRT arithmetical (r=-.28, p=.04; even when controlling for parity judgment RTs: r=-.37, p=.01), but not HRT visuo-spatial subscale scores (r=-.03, p=.82), indicating better arithmetic performances with stronger number-space associations. However, this relation was significantly moderated by age, since the interaction between the parity SNARC effect and age accounted for a significant proportion of the variance in HRT arithmetical scores (ΔR2=.07, b=0.26, t(51)=2.29, p=.03). A significant negative association was observed only in younger children (b=-0.35, t=-3.49, p=.001) aged below 9.5 years (n=29), while the SNARC effect did not relate to arithmetic performance in the remaining older children. This suggests that number-space associations are beneficial for arithmetic performance at relatively early stages of mathematical learning. During the course of mathematical development in childhood, number-space associations then turn superfluous for arithmetic achievement until they possibly become interfering in young adults, who have reached the peak of their developmental trajectory.