Finger Length, Digit Ratio and Gender Differences in Sensation Seeking and Internet Self-Efficacy

Introduction Relative finger length, as a surrogate for prenatal hormonal exposure, has been shown to be related to a wide range of psychosocial factors including sporting potential, sexual orientation, personality, faculty membership, cognitive abilities and even the way men dance (Austin, Manning, McInroy, & Mathews, 2002; Brosnan, 2006; Fink, Neave, Laughton, & Manning, 2006; Lippa, 2003; Paul, Kato, Hunkin, Vivekanandan, & Spector, 2006). The purpose of this study is to extend this research into the domain of self-efficacy within the context of Internet use. The ratio between the index finger (second digit, 2D) and the ring finger (fourth digit, 4D), i.e. 2D:4D has been known to be sexually dimorphic for more than 100 years (Ecker, 1875), with females typically having a higher ratio than males; females = 1 and males = 0.98 for UK samples (Brosnan, 2006). Manning, Scutt, Wilson, and Lewis-Jones, (1998) have suggested that the length of the ring finger is a measure of exposure to prenatal testosterone whereas the length of the index finger is determined by prenatal oestrogen. From this it can be concluded that the 2D:4D ratio provides an indication of the relative exposure to prenatal testosterone and oestrogen. Small 2D:4D ratios produced when the ring finger is longer than the index finger are an indication of greater exposure to prenatal testosterone and might therefore be considered a measure of masculinity. Similarly, larger ratios, where the index finger is equal to or longer than the ring finger, result from greater exposure to oestrogen and therefore might be thought of as a measure of femininity. These sexually dimorphic properties of the digit ratio appear to be consistent across all cultures and are independent of age and overall height (Manning, Stewart, Bundred, & Trivers, 2004). The behavioural and psychosocial correlates with digit ratio appear to be wide ranging. Csatho et al. (2003) used the Bem Sex Role Inventory to assess femininity and masculinity and found that women with smaller digit ratios reported more masculinised scores. Likewise, men with smaller digit ratios are perceived as more masculine and dominant by female observers (Neave, Laing, Fink, & Manning, 2003). Masculine attributes of achievement, ability and speed in sport and visual-spatial ability are also correlated with digit ratio in the predicted direction (Manning & Taylor, 2001). Eysenck and Eysenck (1985) have suggested that the constructs of their personality theory: psychoticism, extraversion and neuroticism have a genetic basis and therefore it might be reasonable to assume a correlation with digit ratio. In a study by Fink, Manning, and Neave, (2004) an attempt was made to correlate digit ratio with the "big-five" personality factors (extraversion, neuroticism, openness, conscientiousness and agreeableness), but only very weak correlations were found. Evidence for a stronger association between digit ratio and personality has been provided by Austin et al, (2002) who looked at the relationship between digit ratio and a number of personality and cognitive tests. The personality tests used were those where it was known a gender difference in performance exists and included measures of psychoticism, neuroticism, extraversion, aggression, sensation seeking and depression. Similarly the cognitive tests of verbal fluency and mental rotation were chosen because of a known gender difference. It was predicted that for the scales where males were expected to score more highly, i.e. mental rotation, aggression, sensation seeking and psychoticism, there would be a negative correlation with digit ratio, whereas for the scales where females would be expected to score more highly, i.e. verbal fluency, neuroticism and depression-proneness, the correlation would be positive. No significant correlations were found for digit ratio and the measures of aggression, mental rotation and verbal fluency. …