Dark Triad Personality Traits, Second-to-Forth Digit Ratio (2D:4D) and Circulating Testosterone and Cortisol Levels

INTRODUCTION

Dark Triad (DT) personality traits (psychopathy, Machiavellianism, and narcissism) show sex differences and associations with hormones. Understanding aetiology may assist in mitigating the harm of these potentially adverse characteristics. Low second-to-fourth digit ratio (2D:4D) is hypothesised to be a marker of high prenatal testosterone exposure and may provide important information about organisational hormones. The aim of the present study was to measure Dark Triad and Big 5 personality traits in relation to digit ratio, salivary testosterone, and cortisol.

METHODS

A non-clinical sample (N=268; 49.25% Female, age M25.20 ± 8.77yrs) completed the Short Dark Triad and International Personality Inventory Pool - Mini. Afternoon saliva was analysed for testosterone and cortisol, and 2D:4D finger ratios were measured.

RESULTS

Males scored higher on DT traits than females. Females scored higher on Big 5 agreeableness and neuroticism. Males had higher testosterone and cortisol levels and lower 2D:4D than females. Digit ratio correlated inversely with salivary testosterone, Machiavellianism, and psychopathy. Testosterone levels correlated positively with cortisol levels and psychopathy and negatively with agreeableness, neuroticism, and Machiavellianism.

CONCLUSIONS

These results provide indications that Machiavellianism and psychopathy (Dark Triad) traits, but not narcissism or Big 5 traits, are linked to markers of prenatal testosterone exposure. Results also replicate sex differences seen in 2D:4D digit ratios, with males having a shorter second-relative-to-forth finger. Links between circulating testosterone, digit ratios, cortisol and personality traits provide further information about potential biological bases of personality.

Are Sexual Desire and Sociosexual Orientation Related to Men's Salivary Steroid Hormones?

Objective

Although it is widely assumed that men’s sexual desire and interest in casual sex (i.e., sociosexual orientation) are linked to steroid hormone levels, evidence for such associations is mixed.

Methods

We tested for both longitudinal and cross-sectional relationships between salivary testosterone, cortisol, reported sexual desire and sociosexuality in a sample of 61 young adult men, each of whom was tested weekly on up to five occasions.

Results

Longitudinal analyses showed no clear relationships between steroid hormones and self-reported sexual desire or sociosexual orientation. Cross-sectional analyses showed no significant associations between average hormone levels and self-reported sexual desire. However, some aspects of sociosexuality, most notably desire for casual sex, were related to men’s average hormone levels. Men with higher average testosterone reported greater desire for casual sex, but only if they also had relatively low average cortisol levels.

Conclusions

Our results support a Dual Hormone account of men’s sociosexuality, in which the combined effects of testosterone and cortisol predict the extent of men’s interest in casual sex. However, we did not detect compelling evidence for an association of within-subject hormone shifts and sexual desire or sociosexual orientation.

Electronic supplementary material

The online version of this article (10.1007/s40750-020-00148-y) contains supplementary material, which is available to authorized users.