Bernhard Fink, Helen Brookes, Nick Neave, John Manning and David Geary

Second to fourth digit ratio and numerical competence in children

Brain and Cognition

The ratio between the 2nd and 4th fingers (2D:4D)—a potential proxy for prenatal testosterone (T) exposure—shows a sex difference, with males usually having lower mean values; the latter potentially indicates higher prenatal T exposure. We studied relations between 2D:4D and competencies in the domains of counting, number knowledge, and visual-number representation in 73 children aged 6–11 years. Significant negative correlations between numerical performance in all of these areas and right and left hand 2D:4D ratios were found for boys but not girls. To the extent that 2D:4D ratios reflects prenatal exposure to T, the implications are (i) high prenatal T may be associated with better performance on some basic numerical measures for boys, and (ii) prenatal exposure to T may affect boys and girls differently with respect to some numerical competencies.