Developing number-space associations: SNARC effects in a color discrimination task in 11-year-olds

Behavioural studies show a relation between numbers and space in adults (DeHevia et al., 2008) and this association arises early in development (Opfer et al., 2010). The SNARC (Spatial Numerical Association of Response Codes) effect consists in faster reaction times (RTs) responding to small/large digits with the left/right hand respectively (Dehaene et al. 1993). It is thought to reflect the automaticity of the number-space link, since it arises not only during explicit magnitude judgment tasks, but also during magnitude-independent parity judgment tasks. Using a parity task Berch et al. (1999) found a SNARC effect in children of 9.2 years onwards, but not in younger children (7.8 years). One major issue raised was that parity judgments might be too difficult and therefore problematic to test young children (VanGalen&Reitsma, 2008). Hence, we designed a color judgment instead of a parity judgment task and tested 33 children from Grade 6 (mean age 11.4 years, SD 0.6). We also assessed number magnitude access using a magnitude judgment task. The results revealed a significantly negative slope in the color task [t(32)=2.47, p<0.01] and in the magnitude task [t(33)=1.75, p<0.05], reflecting a SNARC effect in both tasks (regression method by Lorch&Myers, 1990). A correlation analysis of the slopes of both tasks revealed a positive relationship (r=0.33, p<0.05) indicating that they partly measure the same processes. These results confirm the presence of robust SNARC effects in 6th-graders and indicate that they occur even using a simple color discrimination task that is strictly independent of semantic number processing.