A developmental investigation of the SNARC effect using a colour discrimination task.

How do number-space interactions develop from childhood to adulthood? The SNARC effect (Spatial Numerical Association of Response Codes) reflects the finding that participants respond faster to small numbers with their left hand and to large numbers with their right hand during a number classification task. Typically assessed through magnitude-independent parity judgment tasks, the SNARC effect is thought to show the automaticity of the number-space link. Using a parity task on children Berch et al. (1999) found a SNARC effect no earlier than from 9.2 years onwards. However, we hypothesise that parity judgments might be inappropriate to assess younger children. Therefore a more age-appropriate colour judgment task (implicit) and a magnitude judgement task (explicit) were designed and tested on 363 children from kindergarten to Grade 6 (5.8-12 years). The experimental tasks were complemented by a brief assessment of arithmetic skills. The results revealed overall significant SNARC effects [colour task t(355)=2.6, p<0.01; magnitude task t(340)=4.7, p<0.001], which interacted with grade [colour task F(6,355)=2.18; p<0.05; magnitude task F(6,340)=2.09; p=0.05]. Most interestingly, even the kindergartners already display both effects [colour task t(28)=1.96; p<0.05; magnitude task t(24)=1.7; p=0.05]. These results show explicit and implicit access to numerical magnitude in children as young as 5.8 years.