Second to fourth digit ratios and the implicit gender self-concept

Intersexual and intrasexual variation in the ratio of index and ring finger lengths (2D:4D) is thought to be a marker of fetal androgen and estrogen levels. Thus, 2D:4D ratios have been expected to be associated with the development of the gender self-concept (masculinity vs. femininity). These associations have, however, proven to be empirically rather small and lower than expected. By arguing that early developmental events more greatly influence implicit as compared with explicit self-concepts, we hypothesized that 2D:4D ratios might be associated with the implicit gender self-concept – assessed using an Implicit Association Test – as opposed to the self-reported explicit gender self-concept. Results showed that the implicit gender self-concept indeed significantly correlated with 2D:4D ratios for men, whereas these measures were dissociated for women. In contrast and as expected, we found only small correlations between 2D:4D ratios and the explicit gender self-concept for both sexes.