Height, hands & handwriting: Cues to competition and dominance

Individual differences, contextual- and biological factors play a major role in human behavior. Gathering evidence from different studies, I provide further evidence for the role of well conserved physiological and behavioral mechanisms in human social interactions. I analyzed two different human mechanisms reminiscent of animal body-inflation strategies—height over-report and expanded handwritten signatures—in relation to intrasexual competition, dominance, and narcissism—which can be related to a tendency to impose one’s own interest or aims. Consistent with my hypotheses, I observed a positive correlation between intrasexual competition and inflated-height reports in a sample of male junior soccer players, but not with sociable or aggressive dominance. Similarly, signature size appeared to be positively correlated with sociable dominance and narcissism in a sample of university students, even after controlling for a number of potential confounders, i.e., sex, age, number of characters in printed name, average character size, and signature type. I found a significant association between signature size and sociable dominance, both among males and females, while narcissism was only among females significantly associated with signature size. In addition, I examined the association of prenatal testosterone levels—measured as the second-to-fourth digit ratio (2D:4D)—with actual aggressive behavior and personality traits in adult life. I observed a negative association of 2D:4D ratios—indicative of higher prenatal testosterone levels—and both the severity and frequency of aggressive behavior, as indicated by the type—i.e., none, yellow, or red cards—and number of cards per match awarded to junior soccer players. However, contrary to previous findings, a lower, i.e., more masculine, 2D:4D ratio was associated with less aggressive dominance in the same sample of junior soccer players. With these findings, I hope to have shed light on behavioral cues to competition and dominance, and on the role of prenatal testosterone in competition and aggressive behavior