How different are the brains of women and men? Not much.

Amanda Schaffer has an interesting series of articles at Slate about "The Sex Difference Evangelists", which looks at recent popular science books on difference between the male and female brain by Susan Pinker (The Sexual Paradox: Men, Women and the Real Gender Gap) and Louann Brizendine (The Female Brain):

The bottom line from the science should really be this: Some differences between the minds of men and women exist. But in most areas, they are small and dwarfed by the variability within each gender. To be fair, Brizendine and Pinker intermittently acknowledge this point, and they translate complex material for a wide audience, which necessarily involves simplification. They get credit for trying.

But in the end they don't leave their readers with the correct, if unsensational, impression, which is that men and women's minds are highly similar.

Of course in "translating complex material" Brizendine and Pinker simplify the studies by exaggerating the differences and, in particular, emphasize those that reflect common gender stereotypes. It's not clear, for example, whether women really more empathetic, or are just more likely to fill out surveys with answers that make them appear more empathetic. And it's even more difficult to determine whether the small difference in male and female brains are "innate" or shaped by environment and experience.

Brizendine moves seamlessly from references to fMRI studies to phrases like "distinct female and male brain operating systems." (She also jumps off the deep end with a claim about male and female mirror neurons.) Pinker suggests that fMRI studies can show how women's "neural hardware" gives them an edge in discerning emotion. But our brains change in response to how we use them—what we think, see, feel, and practice doing over a lifetime. This is the plasticity of the brain, demonstrated most colorfully in this famous study of London cabbies. With its potential connection to a person's response to the culture he or she lives in, plasticity could explain much—or potentially all—of the difference between brain scans of men and women responding to emotional stimuli.

And then, of course, is the issue of women and science, which seems to come down to whether more men than women have innately better aptitude for science and engineering subjects. Males do generally perform better than women on tests of spatial reasoning, but like many other skills, training makes a difference.

Researchers from the Spatial Intelligence and Learning Center, which brings together scientists from several universities, conducted a meta-analysis of more than 100 studies that have examined the effects on men and women's spatial-reasoning scores of everything from a few hours with a spatially oriented video game to weeks or months in a classroom to projects like dressmaking. Crunching numbers across the studies, the group found that training was associated with a substantial gain in spatial reasoning—comparable in size to almost a 10-point boost in IQ, according to Northwestern University researcher David Uttal.

And that kind of training can make a practical difference in whether women stick with engineering:

According to a longitudinal study, men and women who received the extra training got better grades in graphics compared with classmates who also did badly on the diagnostic test but did not get further help. What's more, women who got the extra teaching and encouragement were more likely to remain engineering majors: more than 75 percent, compared with less than 50 percent for women who didn't do the training. (For men, for some reason, the extra teaching didn't have this retention yield.)

Despite what some alarmists say, such extra tutoring is not equivalent to forcing women to enter fields they have no interest in, and it's not the same as instituting a quota for female engineering majors. Instead the extra training appears to be allowing some women in engineering to cross hurdles that would otherwise seem insurmountable. It's interesting that the extra teaching didn't seem to help male students in the same way. Maybe the study linked above speculates about the reason, but I unfortunately don't have access to that journal.

Anyway, as Schaffer points out, being able to rotate 3-dimensional objects in your head is not the central focus of most scientists and engineers.

Ultimately, no one really knows what makes a successful scientist. "Sure, mathematical and spatial ability may play a role, but so may creativity, diligence, communication skills, and intellectual risk-taking," says [psychologist Steve] Ceci. Teaching spatial reasoning is a good thing. But overplaying its importance sells a lot of great scientists short.

It would be unfortunate if many women interested in science and engineering dropped out of their majors because of difficulty in classes that require a skill that would rarely be used in a professional setting. I wonder if that just ends up being the final straw for some women who are bombarded with the message that engineering is the realm of men. That message doesn't need to be overt to have a detrimental effect:

In one case, watching a set of TV ads, including one with a woman " 'drooling' with anticipation to try a new brownie mix," seemed to affect how female students answered questions about their educational and career interests. Women who saw the caricaturing ads were less likely to express interest in quantitative pursuits. The ads didn't seem to affect men, presumably because they didn't feel subtly associated with the shallow brownie maven.

And it's those kind of stereotypes of women are hard to avoid. If you watch television at all, you will be bombarded with ads showing women who are ecstatic because they found the best way to mop the floor or remove a stain (see also this ad that equates feminine with "emotional" and masculine with "logical"). The good news is that the detrimental effects of stereotype threat can be counteracted by making contradictory statements.

One striking example is a 2007 study of a top-track calculus class, designed for science and engineering majors, at the University of Texas. This is a pool from which top math and science professionals would be drawn—"the group Larry Summers was talking about," as Aronson puts it. At the beginning of a calculus exam, he gave some of the women in the class a statement that the test had "not shown any gender differences in performance or mathematical ability." These women scored substantially higher on average than their female classmates. They also performed better on average than their male classmates.

So that seems like a simple solution. But there are many people who seem to have a vested interest in emphasizing the differences between the sexes, and books like those written by Pinker and Brizendine simply reinforce stereotypes by making them sound like they have a firm basis in "science", even when they do not.

Go read the whole series, which includes video of discussions between Schaffer and Slate senior editor Emily Bazelon.

Tags: women in science, gender gap, stereotypes