Second to fourth digit ratio and the 'big five' personality factors

Several studies have demonstrated that the ratio between the lengths of the second and fourth digits (2D:4D) is sexually dimorphic. On average males demonstrate lower digit ratios than do females. There is accumulating evidence that 2D:4D is established early in development and is negatively related to prenatal testosterone and positively with prenatal estrogen. In this present study, we investigated associations between digit ratio and the 'big-five' personality factors (extraversion, neuroticism, openness, conscientiousness and agreeableness). Only agreeableness showed a significant sex difference with females scoring higher. Neuroticism showed a significant positive correlation with right hand digit ratio for the whole sample, and in females only for right hand 2D:4D. Further, a significant negative association was found between females' right hand digit ratio and agreeableness. Male 2D:4D did not correlate significantly with any of the personality factors. The results follow previous studies reporting that 2D:4D was a stronger correlate of personality traits in females than in males. In summary, the associations between digit ratio and personality factors are weak but provide some further support for the claim that gender-related behaviour is affected by the amount of steroid hormones present during critical periods of prenatal development