The SNARC effect and its relationship to spatial abilities in women

A classical demonstration of number-space associations is the so-called SNARC (Spatial Numerical Association of Response Codes) effect. It consists in faster reaction times to small/large digits with the left/right hand respectively. To get a better understanding of the well-documented inter-individual variability in the SNARC effect, we investigated the relationship between the classically used parity SNARC and spatial abilities, as indexed by visuo-spatial working memory capacity (WMC). The study population consisted of female university students (n=20; mean age=23.79; SD=2.50) recruited in the fields of humanities and educational sciences. Since systematic studies on the reliability of the SNARC effect are still lacking, we first measured the internal consistency, as assessed by split-half reliability, as well as test-retest reliability of the parity SNARC. Split-half and test-retest correlation coefficients were (r(19)=0.41; p<0.05) and (r(19)=0.25; p=0.14) respectively, indicating a trend towards consistency. In the present female population, a significant negative correlation was revealed between the strength of the parity SNARC effect (mean slope=-10.04; SD=8.66) and visuo-spatial WMC (mean WMC=2.85; SD=1.12; r(19)=-0.51; p<0.05). This finding thus indicates that number-space associations as measured by the parity SNARC effect tend to be stronger in young female adults with higher spatial abilities.