Differential Correlations of Digit Ratio (2D:4D) with Aggressive Dominance and Sociable Dominance Are Not Demonstrated: Commentary on van der Meij, Almela, Buunk, Dubbs, and Salvador (2012, Aggressive Behavior, 38(3), 208–212)

Abstract

Van der Meij, Almela, Buunk, Dubbs, and Salvador reported that, among young men (N = 84), a putative biomarker for prenatal androgen exposure (second-to-fourth digit ratio; 2D:4D) correlated negatively to self-reported aggressive dominance, but not to sociable dominance. A critical examination of this allegedly differential effect shows it to be unsupported and unlikely to be replicable. Statistical power of the sample was so low that the nominally significant correlation coefficient with aggressive dominance and the nominally not significant one with sociable dominance actually did not differ significantly from each other. Apart from these data-analytic and statistical power issues, a number of further substantive comments are raised, including conceptual and study design issues, 2D:4D measurement and reliability issues, and biased presentation (i.e. selective citation) of prior related research evidence. More generally, it is suggested that 2D:4D research would benefit from adopting publishing standards requiring discovery and replication samples (i.e. successful replication of novel findings by the initial researchers themselves), as is now increasingly required for publishing in various fields of inconsistent, hard-to-replicate evidence.

No effects of androgen receptor gene CAG and GGC repeat polymorphisms on digit ratio (2D:4D): a comprehensive meta-analysis and critical evaluation of research

“…The above additional calculations (confidence intervals and power) for the Manning et al (2003) study, in tandem with the findings of the meta-analysis, illustrate some important points about the associations of study power with the reproducibility of study findings, which are relevant for other subliteratures of 2D:4D research as well (see Voracek 2013aVoracek , 2013b. Underpowered studies are an endemic problem in empirical research (Button et al 2013).…”