Yesterday, we discussed sex differences at the highest levels of achievement and found that there are some significant differences between males and females. But despite these observations, it’s still unclear why the disparity exists, and what can or should be done about it.
Sex differences in brain structure
One possibility is that the physical structure of the brain is different for males and females. MRI imaging shows that males do have larger brains than females on average. But women have a higher proportion of “gray matter” — the part of the brain where most cognitive activity is believed to occur. Indeed, there is no significant difference in the amount of gray matter in male and female brains. However, one white matter structure in female brains — the corpus callosum — appears to be bigger than in males (though different studies are more or less successful in replicating this observation).
The corpus callosum is where most communication between brain hemispheres occurs, and it appears that female brains are more effective at coordinating both hemispheres. Male brains, by contrast, appear to have more connectivity within each hemisphere than female brains. There also appears to be some correlation between these physical differences in brain structure and mathematical ability. The coordination of both hemispheres is associated with better language skills, while the connectivity within hemispheres is associated with better math skills.
But there is plenty of research demonstrating that the physical structure of the brain changes as new knowledge is acquired. Are the differences in brain structure the cause or the effect of sex differences in math skills?
It seems unlikely that all these differences could be acquired during a lifetime, but it also seems probable that a different environment could mitigate or eliminate these differences. And let’s not forget that despite the apparent advantages of male brains, there are still plenty of women who demonstrate exceptional ability and achievement in math and science.
Social and cultural influences on sex and math/science
The evidence for social influences on math/science ability is so vast that it is difficult for me to condense the information contained in Halpern et al.’s article in a narrative form. However, it is also problematic because so much of the data consists of correlations. For example:
- Parents’ expectations of their children’s math and science achievement correlates with their actual achievement
- Parents encourage sex-typed behavior (e.g. fathers prevent sons from playing with dolls)
- Boys outperform girls in high-ability math tracking courses
- Parents allow boys to roam more than girls (perhaps favoring navigation/visuospatial skills)
- Children see math skills as masculine
- Teachers offer more encouragement to boys in math and science classes
- Boys are more likely to have computers than girls
Is the differential treatment of boys and girls causing the differences in achievement and ability, or is the reverse occurring?
There is some evidence that once the stereotype of boys being better at math and science is invoked, it results in diminished performance by girls. We’ve reported on some of this research on CogDaily. But just because stereotype threat appears in a lab, when stereotypes are deliberately invoked, does it mean that women actually do worse in real-world testing situations. One study found that if the AP Calculus test gathered race and gender information before the test, 5.9 percent fewer females and 4.7 percent more males passed the test, compared to if the information was collected after the test.
Finally, there is considerable evidence that actual discrimination against women continues to occur. While it may not be the old-fashioned, active discrimination that occurred decades ago, both laboratory research and analysis of actual hiring patterns show that discrimination is still with us.
One of the more interesting lab studies asked volunteers to rate prospective job applicants. When the job was seen as a “male” job, applicants who were men were rated higher than women with identical qualifications. The reverse occurred for “female” jobs.
A 2005 study of medical students found that female students who had experienced discrimination or harassment were more likely then men to change their choice of specialty.
And a Swedish study in 1997 reviewed applications for post-doc appointments there. The researchers devised a formula to rate the qualifications of each applicant. They found that the women who ranked highest using their formula (scoring 100 or above) were rated as equivalent to the lowest-ranked men (scoring 20 or below) by the peer review board. All other women in the sample were rated lower than all the men in the study.
So it appears that there are a wide variety of social factors that affect (or are affected by) sex differences in math and science. Because of limitations in the way these studies can be controlled, it’s difficult to say that discrimination or differential treatment cause the sex differences we see in math and science. But the converging evidence from many different study methodologies suggests that these social differences are an important factor.
Finally, even if it is conclusively demonstrated that men are, on average, better built for careers in math and science, the disparity in actual employment figures is much larger than the differences in abilities that have been identified. Surely we can do better at helping women succeed in math and science.
Halpern, D.F., Benbow, C.P., Geary, D.C., Gur, R.C., Hyde, J.S., & Gernsbacher, M.A. (2007). The science of sex differences in science and mathematics. Psychological Science in the Public Interest, 8(1), 1-51.