The effect of prenatal androgen exposure on the development of neural reactivity systems: A study of the HEXACO Personality Inventory

The ratio of the lengths of the second and fourth digits of hands (2D:4D) seems to vary as a function of systematic differences in prenatal androgen exposure (Hönekopp & Watson, 2010). The 2D:4D ratio has been shown to be related to a variety of personality attributes. This study predicted that 2D:4D would covary with scores on the emotionality dimension of the six-facet HEXACO personality assessment, due to emotionality’s relationship with neural reactivity systems controlled by the amygdala (Hines, Allen, & Gorski, 1992), but that 2D:4D would relate to no other facet. Consistent with hypotheses, data showed that men had smaller ratios than women on both the right, t(405) = 2.84, p < .05, d = .28, and left hands, t(405) = 4.51, p < .05, d = .45, and the relationship between 2D:4D and emotionality was outside of sampling error of zero, r = .18, p < .001. Additionally, 2D:4D was unrelated to the remaining HEXACO facets. Findings suggest that prenatal testosterone exposure has an organizing effect on personality traits.

► First study to examine prenatal androgens effect on the development of HEXACO personality traits.
► As hypothesized, this study found that 2D:4D was related to the emotionality dimension, r = .18, p < .001.
► As predicted, the 2D4D—other-HEXACO-dimension relationships were within sampling error of zero.
► Offers explanation for why previous 2D4D-Big Five findings are inconsistent.