The impact of inhibition capacities on number-space associations

Numerical and spatial representations are tightly linked (for a review see de Hevia et al., 2008). One specific instance of this link is the finding that when doing a binary classification judgment on single Arabic digits, participants are faster to respond with their left/right hand to small/large numbers respectively. This observation has first been described by Dehaene and colleagues in the early 1990’s (Dehaene et al., 1993) and termed the SNARC effect (Spatial Numerical Association of Response Codes). Celebrating its 20th anniversary this year, the SNARC effect has been extensively replicated (for a meta-analysis see Wood et al., 2008) but one of its characteristics remains its high inter-individual variability (Wood et al., 2006a; 2006b). The source of this variability can partly be ascribed to differences in mathematical proficiency (Hoffmann et al., submitted) but a more domain general hypothesis implicating general inhibition capacities warrants further investigation. For the present study a total of 77 participants have been evaluated with a SNARC paradigm as well as standard inhibition tests (Stroop, Incompatibility subtest of the TAP test). Results show that when age-appropriate inhibition tests are used, inhibition capacities are strongly correlated with the SNARC effect, in the way that very efficient inhibition capacities lead to weaker SNARC effects. Consequently this finding could at least partly explain the impact of arithmetical proficiency on the SNARC effect. A study combining both measures would be an appropriate next step.