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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.

Why aren’t there more women in science and math? Part 1
Why aren’t there more women in science and math? Part 2

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.

Comments

  1. #1 Gerard Harbison
    September 27, 2007

    What these articles are notably missing is a discussion of the effects of CAH on the abilities of girls at spatial rotation and similar tests. IMVHO, these are rather persuasive evidence that early androgen exposure may have a lot to do with the development of stereotypically ‘male’ cognitive abilities.

  2. #2 Josh Schraiber
    September 27, 2007

    TAKE THAT STEVEN PINKER!!!!!!

  3. #3 Matthew L.
    September 27, 2007

    Re: No. 1, I wouldn’t be so sure about mental rotation and androgens either. If you do a google search for “practice mental rotation” you’ll find a number of studies linking practice at mental rotation tasks to increased performance, and “masculine” activities tend to involve skills of a similar nature more than “feminine” ones. I think I even recall a study that found that practice at mental rotation tasks not only increased everyone’s performance, but reduced the average male-female gap (can’t find it though, if anyone knows where such a result is, I could use a citation).

    Besides all that, as Steven J. Gould pointed out (in the “Mismeasure of Man”), innate doesn’t necessarily imply insurmountable. Nearsightedness is almost certainly a genetic deficiency in vision (at least in part), but is easily compensated with eyeglasses.

  4. #4 Kay L.
    September 28, 2007

    I’m a female chemist, working in industry. When I was an undergraduate (in the early 90′s), my major was close to half female, which is fairly high for chemistry. But as I’ve kept up with them over the years, I’ve seen a lot more of the women drop out of science – I’m one of the few left who is still a bench chemist. I’ve seen the same thing with my colleagues in industry – I’ve been through a few rounds of layoffs (a common scenario in the pharma industry) and every time, a significant number of the women leave science altogether rather than finding another job in chemistry.

    The reasons are varied, and they aren’t as clear-cut as “sex discrimination” or an “old boys network”. A lot of it had to do with family issues, as well as the science job market – in my field, you often have to pick up and move every few years as you deal with layoffs. Not very family friendly. Many science jobs are geographically limited – at least in chemistry, research jobs are hard to find outside of the northeast and California. If you take time off (either for children or because you can’t find work in science where you live), you’re often seen as “not serious” or “out of touch”. A lot of my female colleages just said “it’s not worth it – I can get a job somewhere else”.

    That doesn’t explain why women aren’t going into science in the first place (although I have a hard time recommending my field to young women, not because of the work itself, which I love, but because of the job market, outsourcing and teh family issues) but it’s frustrating to think of the women who were part of the minority who loved science, and made it through the years of education, and then left the field in frustration. That’s one reason my workplace is 90% male, even though my college chemistry classes were a lot closer to 50-50.

    Karen

  5. #5 Andy
    September 28, 2007

    Karen — Chemistry seems to be an area where women have particular difficulty getting to parity, but some departments do much better than others. Eg the UC Davis Chemistry Department has about 25 percent (10 women from 38 faculty), compared to a national average of 12-13 percent.

    Wired notes that on this day, Sept 28 1865, Elizabeth Garrett Anderson was the first woman to get a medical license in the England. Women were not formally admitted to British Medical schools until 1876 (Garrett Anderson found a loophole).

    Now I would guess that the student body of most med schools is 50 percent female or more. In our School of Veterinary Medicine, it’s 80 percent female.

    Did women’s brains become miraculously more powerful in the last 132 years, allowing them to become doctors and vets?
    I think not.

  6. #6 Michael Chermside
    September 28, 2007

    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.

    I would like to see a citation on that, because I find this not even remotely credible. (The conclusion, not the fact that the study existed.)

    I am willing to believe that asking race and gender beforehand has some effect. However, the AP Calculus test is a rather long and difficult test. The question about race and gender is a brief checkbox. Perhaps the memory of the race/gender question would linger for the first couple of minutes, but surely (given the level of concentration needed to take such a test) all memory and effects of such a question would have disappeared before the test taker got far into the test. Differences on the order of 5% are just not believable.

    – Michael Chermside

  7. #7 Jacek Z.
    September 30, 2007

    “Did women’s brains become miraculously more powerful in the last 132 years, allowing them to become doctors and vets?
    I think not.”

    There is also a possibility that that education system was more demanding 132 yers ago.

  8. #8 Eric Schwitzgebel
    September 30, 2007

    I suspect ability and motivation (both current and through the course of one’s education) are closely intertwined, and many things affect motivation. Graphs and discussions of this sort, intentionally or not, seem to me to evoke dubious ideas of a measurable and pre-determined innate ability.

    What do you think?

  9. #9 Lauren
    October 1, 2007

    What about video games?

    It has been demonstrated many times that playing video games can be a cognitive workout. I don’t have anything I can link to support this, but I did hear that it connects neural pathways that are not normally stimulated. There are many more boys playing video games than girls. Could the mental sweat caused by video games strengthen the areas of the brain more involved in mathematics?

  10. #10 Dave Munger
    October 1, 2007

    Lauren: Interesting hypothesis. I’m not sure how well it pans out though. If anything, girls have been closing the math achievement gap in recent years, just as video games have become more popular. But this article says boys play a lot more games than girls, so you may have a point…

  11. #11 Theo Bromine
    October 1, 2007

    One the one hand, given the biological differences between men and women, it would be surprising if there were *not* statistically significant measurable differences between average intellectual and cognitive abilities in some areas. But on the other hand, even in the studies where we cannot separate innate from learned behaviour, differences among individuals of the same gender continues to be far greater than differences between the gender averages.

    How do we know if there are “too few” women in math, science, and technology? Just about everyone (or at least everyone I consider worth listening to) agrees that females and males should have equal opportunities and encouragement to enter whatever field they choose. If females are not going into math/science/technology, is it because they are discouraged, or because they are not capable? And if females are not capable, is it because of their biology, or because they only played with Barbie instead of Lego when they were growing up? (Which raises a question about the video game comment: Does playing video games make males better at M/S/T, or does the quality that makes males interested in video games also make them interested in M/S/T?)

  12. #12 David Levy
    October 2, 2007

    I can’t help but notice some issues I would consider as potentially major ones haven’t gotten any attention at all, for example:
    - The actual INTEREST in the maths and science subjects might vary between sexes according to numerous reasons. Ability isn’t the only factor.
    - Test performing isn’t necessarily linearly correlated with creativity (and thus, successfulness) in the tested field. When you get into research, for example, it’s no longer a matter of studying and spewing the information your absorbed in tests, but rather implementing old studies in new situations. Creativity and assertiveness are a necessity and these were overlooked.
    - Lack of technical affinity might repel women from engaging in these subjects in the first place. Even though this might be a socially born trait, technical affinity being stronger or more common in males (which is, in my experience, the reality) can be easily explained by evolutionary means.

    So this is an insightful three day article, but I think there is still much to be explored and questioned.

    And if we go one step back – if Women who WANT to have careers in science are able to do so – why say “Surely we can do better at helping women succeed in math and science.”?

  13. #13 Theo Bromine
    October 2, 2007

    And if we go one step back – if Women who WANT to have careers in science are able to do so – why say “Surely we can do better at helping women succeed in math and science.”?

    How do we *know* that women who want M/S/T careers are able to get them? These days, at least in North America and western Europe, I am not aware of any cases of official gender biases (ie by law or policy) that discourage or prevent women from entering M/S/T fields, but that is relatively recent (~30 years by my experience). I don’t think this has been enough time to dis-entangle the innate from the learned technical affinities and aptitudes, especially since there are still lots of non-official discouragements against women in M/S/T.

  14. #14 Dave Munger
    October 2, 2007

    To follow up on #12 and #13–

    What is an acceptable definition of “want”? There was a point in American history when most women didn’t “want” the right to vote. If girls are encouraged to play with dolls and not Erector sets or video games, if teenage girls are encouraged to worry about their looks while teenage boys are encouraged to worry about their cars and their football games, if women in college are discouraged from pursuing “male” careers such as surgery and engineering because the environment seems hostile to them, is it any wonder that many women don’t “want” these careers?

  15. #15 Alford Findley III
    October 2, 2007

    Motivation is huge in achievement and progression in any competitive field of endeavour. Stereotype threat data suggests very weak motivation in those who succumb. We should be asking why so many young people are so easily discouraged? How can we correct the problem?

    Perhaps a lack of confidence mirrors a lack of competence from poor early education? I suspect so.

  16. #16 Theo Bromine
    October 3, 2007

    Perhaps a lack of confidence mirrors a lack of competence from poor early education?

    Again the question comes back to why there is a difference between motivation levels for women vs men in M/S/T. If I recall the stats correctly, in North America there are more women than men in college/university. So there is apparently sufficient motivation for lots of women to go to university, but insufficient motivation for M/S/T? Why the disparity?

  17. #17 Justin Moretti
    October 4, 2007

    #14: girls are encouraged to play with dolls and not Erector sets or video games, if teenage girls are encouraged to worry about their looks while teenage boys are encouraged to worry about their cars and their football games

    Agree completely.

    I utterly refuse to buy my little girl cousins dolls, or any other ‘girly’ toys (fairy costumes, little-girl-themed kids’ DVDs etc). If they get anything from me it’s Lego (usually a general-construction set of assorted pieces), a book (most often general science-type concepts and experiments that children can do with a little adult help), a puzzle of some kind (pitched at their age level and up, to ensure they’re stretched), or a book voucher (which they can do with as they please).

    If, God forbid, I had to take them to McCanc… er, the Golden Arches, I would get them the toy that was being pitched at the boys. At least they do something – like throwing off a projectile, or racing/walking their way across the table, or something similar, that can (be used to) excite their minds to ask “how does this happen?”, or even better, “What happens if I…?”

  18. #18 INTPLibrarian
    October 4, 2007

    Why don’t women who are interested in math and science enter those fields? I really think a large part of the answer to this is found in this:

    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.

    Merely anecdotally, it’s been my experience that women are much quicker to drop out of activities if they feel harassed (not necessarily sexually) or teased or are given a hard time about it, than men are.

    When I was in a Computer Science program (which I dropped out of eventually), a female professor told me that I was going to do poorly in some classes and that was true of everyone. The difference between men and women were that the women thought that meant they were failing and incapable of the work whereas the men simply realized they couldn’t excel at every single assignment.

    Does anyone know if there are any studies addressing this?

  19. #19 Tatiana
    December 9, 2007

    As a female in engineering, I want to say that I have had to push hard against the tide for my whole career in order not to be sidelined or channeled into girly jobs, meaning something clean, quiet, and far away from the real bread and butter business of the company. Women who are assertive are seen as rude and unpleasant, men who are assertive are seen as competent and confident. It’s so pervasive that it’s like water to a fish. Most people don’t want to have to swim against the tide their whole lives. It is tiring.

    Time and again I’m treated as someone who is incapable of understanding the finer technical points, when in fact, the exact opposite is true, and I often end up researching and teaching my vendors and supposed experts what is actually going on with their own systems.

    With each new group of guys I interact with, there’s a learning curve where they lose their stereotypes and finally deal with me as an individual. After that we seem to do quite well. But it is exhausting having to break through the fog with every new group of guys.

    I’ve been told to get my male boss on the phone who can understand these issues, when I have questions that the vendors aren’t answering. When I explain what I need, I’m told I can’t have that, only to kick it upstairs and have my male boss told that of course we can have that (drawing, information, specification, whatever). I have to struggle to be taken seriously with each new group of men in my overwhelmingly male profession.

    Other people would give up, male or female. I keep going because I love what I do and I’m good at it. Also, I’m desensitized to people telling me I can’t do things because I’m a girl. I got that all my life and it always turned out to be untrue.

    But good heavens, don’t think that women don’t face constant pressure to just go along. We do. Those of us who remain are more determined and tenacious than ordinary men and women.

  20. #20 Steve M
    December 9, 2007

    Why is there such a huge obsession with getting more women into traditionally male jobs, but not vice versa? Why do we never see hysterical articles about the lack of male nurses, primary school teachers, and the like? Don’t tell me it’s “status” – scientists are more typically poorly paid bureaucrats than masters of the universe.

  21. #21 randy
    December 10, 2007

    regarding this source of male-female difference:
    Teachers offer more encouragement to boys in math and science classes

    it has been my finding (anecdotal and based on my kids and friends kids) that the exact opposite is happening. In fact, girls (such as my daughter) who were gifted in math, but chose humanities were essentially spit on and dropped like a hot potato when it came to scholarships, awards, recognition and general attention.

    The quickest route for girls to receive any of he above (and benefit of the doubt in grading situations, AKA grade inflation) was to play the game and pretend to be interested in math and science.

  22. #22 Natalie
    November 30, 2008

    Re: #18 When I was in a Computer Science program (which I dropped out of eventually), a female professor told me that I was going to do poorly in some classes and that was true of everyone. The difference between men and women were that the women thought that meant they were failing and incapable of the work whereas the men simply realized they couldn’t excel at every single assignment. Does anyone know if there are any studies addressing this?

    Carol Dweck has researched how views of intelligence affects self-efficacy, and how gender roles are influence by views of intelligence. During development, children do not have a strong sense of self and as a result may be sensitive to social feedback. Children who are given person-oriented praise (e.g., “Kelly is smart”) as opposed to effort-based praise (“Kelly must have worked hard”) will tend to see their identities as contingent on their success. For example, in one experiment, children were given choices of two puzzles, one more challenging than the other. Both groups were told that if they chose the harder task, they would learn more. Those who were given person-oriented praise tended to choose the easier task, while those given the effort-based praise tended to choose the harder task.

    Dweck addresses how girls who succeed in math during primary and secondary school are more likely to get discouraged in college when they confront challenges. Likely, this has to do with social conditioning. She also posits that boys tend to get in trouble more (perhaps because parents allow them to roam more than girls, as stated above), and parents given them the effort-based praise as a consolation prize.

  23. #23 Louise
    January 21, 2009

    Is this true that people who have more art/imagination gene are lack of math/logic gene?

  24. #24 yours truly
    November 16, 2009

    Is it so hard to say”chicks are dumb at maths?”

  25. #25 Æ HIll
    November 17, 2009

    Sex or gender, are they different? There can be no dispute that males and females are and will be different. From a basic and practical viewpoint, they have to be different. The lines have been blurred regarding procreation; nevertheless, we have a sperm and an egg. Who is to say one is more important than the other? Although there are many perspectives about this question, the fundamentalist [non-religious connotation intended] viewpoint usually finds no importance differential. That is to say, we need both egg and sperm, but they are different.

    As the genes are different, so the chromosomes, the gamete, the fetus, the child, the adult, and social orders are different. That does not equate to any difference in significance, albeit many have so behaved.

    From today’s vantage, it has become obvious that one-hundred years past, society was different. The rights of a female in the Western World were clearly denigrated compared to today’s standards. Speaking of primordial responses, the hair stands up on the back of my neck as I read accounts like that of Rosalind Franklin. This is a scientist who died at an early age having been exposed to high levels of radiation while finding the critical bit of evidence to understand the structure of DNA.
    [see: http://books.google.com/books ?id=sgqFuy4LGb0C&printsec=frontcover&dq=rosalind+franklin&ei=bfYCS6TSG4m4kwTVkrSVDw]
    Hey Watson, what crook has her Nobel Prize? Although the Nobel Prize is often cited as some kind of elite indication, Rosy as a female is not the only illegitimate runner up. Society of the time has influenced Prize winner choices for other reasons than gender. There are too many exceptions for my approval. One of many examples would be Nicola Tesla, by far the greatest contributor to our society today than most, if not all, other scientists, but especially Thomas Edison with his Noble Prize. One of many contributions by Nick, was the “Poly Phase Electrical Distribution System.” Or as societies the world over are indebted, “AC” electrical power, from generators to transformers to motors, all from the mind of a prodigy working in his head. If Rosy’s sin was being a female, Nick’s was that of being a bit eccentric [i.e., OCD, many great people were mentally ill].

    All societies are replete with examples of the chosen few and the unfortunate many, distinctions that are generally unfounded and unjust. Where could we possibly find equality? If you lack faith in a god, it would seem to be far off into the future, if ever we correct most of the injustices in society.

    Bethany [of Kauai] embraced the circumstance of having lost her right arm to a shark; her indomitable spirit is an inspiration to all. Her future would not be so bright if she were campaigning for the killing of sharks everywhere. Sharks are just part of the world, she not only moves on, but has inspired many more people by clearly doing what she sets herself to achieving.

    Females need to take her lesion to heart. We all have our own greatnesses to develop – within the world that is. I tell you truly, the greatnesses correlated to being a female human, are many. Changing Society may be worthwhile, if in your heart social change is your bag, but if science is your bag, find your opportunities to excel within your field of science. Oh, yea, same goes for the guys.

    As to neurological or physical differences, I say, “So what?” What can you make of the fact that the corpus callosum is used to confabulate? Are women better lairs because of their prominent corpus callosums? Are men better lairs because their corpus callosum is better connected? Grey mater size; x, y differences; bicep size; having a right arm; corpus callosum size; body size; skin color; geographical location; all may influence your life and your work, the wise person will achieve greatness not just in spite all of these circumstances, but by utilizing all of their circumstances. Let Nature nurture.

    If you are into social change, be reassured, it will happen. Pick your windmill and tilt away. Sometimes, being blind to prejudice trumps prejudices, but not always. As the jailbird said:

    “[Nonviolent direct action] seeks… to dramatize the issue that it can no longer be ignored. My citing the creation of tension as part of the work of the nonviolent resister may sound rather shocking. But I must confess that I am not afraid of the word “tension.” I have earnestly opposed violent tension, but there is a type of constructive, nonviolent tension which is necessary for growth. Just as Socrates felt that it was necessary to create a tension in the mind so that individuals could rise from the bondage of myths and half truths to the unfettered realm of creative analysis and objective appraisal, so must we see the need for nonviolent gadflies to create the kind of tension in society that will help men rise from the dark depths of prejudice and racism to the majestic heights of understanding and brotherhood.” — King, Martin Luther Jr., “Letter from a Birmingham Jail”

    In his time, “brotherhood” included sisters, now they feel excluded. Was that progress? Peace and understanding to the ‘hood.

    Rock on David,

    Æ Hill

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