Relative Finger Lengths, Sex Differences, and Psychological Traits

@article{Loehlin2009RelativeFL,
  title={Relative Finger Lengths, Sex Differences, and Psychological Traits},
  author={John C. Loehlin and Sarah E. Medland and Nicholas G. Martin},
  journal={Archives of Sexual Behavior},
  year={2009},
  volume={38},
  pages={298-305}
}
Various finger length and personality and ability measures were obtained for a sample of Australian adolescent twins (306 boys and 397 girls). A new measure of relative finger length (the length of a given finger relative to the sum of all four fingers) was investigated, and shown to be superior to the traditional 2D:4D for discriminating between the sexes. It also had the advantage of permitting a more analytic approach: for example, the 2nd finger-length contributed much more than the 4th… 
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References

SHOWING 1-10 OF 46 REFERENCES
Finger lengths, 2D:4D ratios, and their relation to gender-related personality traits and the Big Five
  • R. Lippa
  • Psychology
    Biological Psychology
  • 2006
Relative Lengths of Fingers and Toes in Human Males and Females
TLDR
For both homosexual females and homosexual males, nearly all of the length ratios for fingers were intermediate to those for heterosexual females and heterosexual males; that is, the ratios of homosexual females were masculinized and those of homosexual males were hypomasculinized, but few of these differences were significant.
Sex hormones and finger length: What does 2D:4D indicate?
Population Differences in Finger-Length Ratios: Ethnicity or Latitude?
TLDR
The Australian 2D:4D ratios resembled those in Britain rather than those in the U.S., tending to exclude hypotheses related to latitude and making differences in gene pools a plausible explanation.
Sex dimorphism in digital formulae of children.
TLDR
Test for a sex difference in the relative lengths of the finger bones, including the second-to-fourth digit ratio (2D:4D), using left-hand radiographs taken in young children indicate that relative digit lengths are sex-dimorphic in children, and suggests that 3D: 4D may be a better marker of perinatal sex differentiation.
Gender Differences in Relations of Mental Rotation, Verbal Fluency, and SAT Scores to Finger Length Ratios as Hormonal Indexes
TLDR
Better cognitive performance was associated with a less gender-typical finger-length ratio, for both men and women in this group of college students, and a possible curvilinear relation between hormones and cognition in normal populations is discussed.
Finger length and distal finger extent patterns in humans.
TLDR
The sexual dimorphism in finger measures is more strongly expressed in the distal extent of fingertips than in the length of fingers, with smaller between-finger differences for females than for males.
A Reanalysis of Five Studies on Sexual Orientation and the Relative Length of the 2nd and 4th Fingers (the 2D:4D Ratio)
TLDR
It was the 2D:4D values for the heterosexual participants that varied most, particularly between the USA and the British studies, and these were responsible for many of the discrepancies in the conclusions across studies.
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