Although I don’t plan to specialize in women’s issues in my writing, I have been working on a couple of articles on gender and kept up with the research for several years. The recent Ceci and Valla paper in “Perspectives on Psychological Science” dovetails with some of the issues in one of my articles. Since the middle of the aughts, Steve Ceci and Wendy Williams have been looking at sex differences in science and math. Though, Williams didn’t work on this publication.
It evaluates the most prominent “nature” account for sex differences in abilities, preferences, etc. that are relevent to success in science. The thrust of this story is that during a critical period in pregnancy, hormonal surges differentiate male and female fetuses. Behavioral sex differences are among the consequences, and they are mediated by the effects of hormones on the brain.
As Ceci et. al 2009 puts it,
Biological Sex (Hormones)—>Brain—>Sex Differences in Abilities, Interests, and Preferences
(model A2 in section 1 of the Supplemental Materials of their study “Women’s Underrepresentation in Science: Sociocultural and Biological Considerations”).
Ceci and Valla use the data on the 2D:4D to evaluate these ideas. 2D:4D is the ratio of the index finger to the ring finger. Many investigators use it to proxy for androgen exposure during the critical period.
Initially, one sees strong support because so many studies report effects. However, Valla and Ceci reveal inconsistent results, especially when considering effects in both sexes. They highlight three major points beyond inconstiencies. Firstly, what kind of a relationship between prenatal hormones and attributes for success in science? Is there a linear relationship where the higher up androgen exposure during gestation, the superior brain organization for developing attributes conducive to success in science?Or is the low-male range optimal? Some findings show males with feminine ratios perform better on mathematical and spatial tests than males with more masculine ratios.
Moreover, current research doesn’t distinguish between brain organization that endows boys with higher cognitive ability for some quantitative and spatial tasks and a preference for activities that develop these abilities.
Cue the diagram
Hormones–>Brain—>Male Typical Cognitive Profile
Hormones—>Brain <—> Experience (e.g. activities that tax visuospatial systems) ->Male Typical Cognitive Profile
Hopefully, consideration of these big-picture questions will improve researchers’ understanding of prenatal hormones’ contributions to sex differences in science careers.
There is a basic question about the relationship between digit ratio and the exposure to prenatal hormones. Valla and Ceci don’t discuss some of the most relevant publications, those dealing with “experiments of nature,” or hormonal disorders. To summarize the implications of the findings, Marc Breedlove on this approach:
The correlation between 2D:4D and prenatal androgen stimulation is too imperfect to accurately predict the phenotype of a particular individual, even in terms of sex. However, digit ratio is the best available retrospective marker of average differences in prenatal androgen stimulation between groups of people, and/or correlations of prenatal androgen stimulation with particular behaviors and characteristics within a group. Thus digit ratios offer a valid test of the organizational hypothesis that androgens act early in life to masculinize various human behaviors. “
The idea of a mixed relationship between prenatal exposure to hormones and attributes for success in science using this method is not new. Puts et. al 2008 did a meta-analysis (which was noted in Ceci et. al 2009) finding weak relationships.
Most of these are legitimate criticisms. Androgen probably impacts abilities directly (at least IN PART), because we see differences emerge quite young in life. Liben and Quinn and Moore and Johnson, both 2008, found sex differences in spatial ability among infants. Many studies have documented girls acquire language earlier.
Finally, there is more to inborn factors of sex differences than prenatal hormones. In interviews, researchers noted other important periods: Amy Shelton thought pubertal hormone exposure was more significant for adult sex differences in cognitive ability, and Diane Halpern commented hormone surges after birth are probably more important than exposure in utero.