Tuesday, September 30, 2014

Girl Brains And Boy Brains, Take #456789. By Dr. Michael Mosley

The BBC Horizons had a program on this idea:

Do you have a "male" or "female" brain? Are there really significant brain differences between the sexes and if so, do these differences matter? BBC Horizon investigates.
When it comes to the tricky and explosive question of how much, if at all, male and female behaviour is driven by brain differences, Professor Alice Roberts and I sit on different sides of the fence.
I believe that our brains, like our bodies, are shaped by exposure to hormones in the womb and this may help explain why males tend to do better at some tasks (3D rotation), while women tend to do better at others (empathy skills), although there is, of course, an awful lot of overlap and social pressure involved.
Alice, on the other hand, thinks these differences are largely spurious, the result of how the tests are carried out. She worries that such claims may discourage girls from going into science.

The debate between Roberts and Mosley may have been quite good, even wonderful, but I'm not writing about that since I haven't watched it.  Instead, I want to write about this advertisement for it by Michael Mosley.  Or call it priming?

Yes, it's priming.  We are introduced to Mosley's arguments in great detail, from 3D rotation to empathy skills to, later, specific pieces of research.  We are not introduced to any of Roberts' arguments, except in the general sense that she believes the differences (all of them?) are largely spurious, based on how the tests are carried out, and worries about girls being discouraged from going into science.  Thus, we get one set of arguments in great detail and nothing but vague noises from the other set of arguments.  Perhaps this is understandable.  Mosley obviously wants to present his point of view as the correct one.  But it's important to note how the story is told.

This is particularly important, because the two pieces of research Mosley particularly mentions are pretty controversial ones!  He loves the work of Simon Baron-Cohen (the PS to this post is a good explanation why Baron-Cohen's basic theory about what distinguishes the female brain from the male brain is problematic) and he loves the Ingalhalikar et al. brain imaging study (which I covered in some detail here and its reception here and here).  To pick those two as examples of solid and sound research on biological sex differences in the brain is a bit shocking.

Mosley likes Baron-Cohen's idea of the female brain as mainly good at empathizing:  understanding the emotions of others and relating to them,  and the male brain as mainly good at systemizing:  the analysis, creation and understanding of systems.  If that sounds a bit like the old argument that women are emotional and men are rational, well, it is in the same family.  There's no earthly reason why a person cannot be both empathizing and systemizing or (almost) neither*, yet the basic theory  treats the two as competing and sex-linked characteristics.  And that's why men are more likely to be nerds:

One of the scientists who has most strongly influenced my beliefs is Professor Simon Baron-Cohen of Cambridge University.
He argues that, broadly speaking, there are two different "brain types". There are empathisers, who are good at identifying how other people are thinking or feeling, and there are systemisers, people who are more interested in trying to take apart and analyse systems i.e. people who are a bit nerdy.
We are all a mix of the two, but most of us are more one than the other. Men tend to sit more along the systemising end of the spectrum, women at the empathising end, though there are plenty of exceptions.

Got it?  If not, you should go back and re-read the end of this post.  Then notice that Mosley, too, interprets empathizing and systemizing as mostly mutually exclusive characteristics.

And created by biology, especially by the amount of testosterone a fetus may have experienced during pregnancy:

But is this simply the product of social conditioning? Professor Baron-Cohen thinks not, that exposure to different levels of hormones in the womb can influence the brain and subsequent behavour. Some of his most intriguing findings have come from on-going research into a large group of children who have been followed from before they were born.
At around 16 weeks gestation, the children's mothers had an amniocentesis test, which involves collecting samples of the fluid that bathes the womb. The researchers measured levels of testosterone in the fluid and have since discovered intriguing links between those levels and behaviour.
"The higher the child's pre-natal testosterone" Professor Baron-Cohen told me, "the slower they were to develop socially. They showed, for example, less eye contact at their first birthday". They also had a smaller vocabulary when they were toddlers and showed less empathy when they were primary school age.
On the other hand he found that being exposed to higher levels of testosterone in the womb seems to enhance some spatial abilities. "Children with higher levels of pre-natal testosterone were faster to find specific shapes hidden within an overall design."

The research into fetal testosterone (fT) and its effects is actually quite complicated (writes she, exhausted, after hours of reading) and as far as I can tell different studies analyze pretty different things and their findings differ accordingly.  But it's true that almost all research into empathizing vs. systemizing and fT is carried out by Baron-Cohen and his colleagues.

So I tried to learn about the "large" sample of children mentioned in the above quote.  I may have failed to find the correct studies (it seems that Baron-Cohen's group had one small sample of children and their mothers and then a larger sample**) but the results mentioned in the above quote seem to match the ones I find for a fairly small sample of children. 

Take that reference to children with high pre-natal testosterone showing less eye contact at their first birthday:  This is the only study I found about it:

Amniotic fluid was analysed for foetal testosterone (FT) level. Postnatally, the infants (29 girls and 41 boys) and parents were filmed at 12 months of age, and the amount of eye contact made by the infant to the parent was recorded. Girls made significantly more eye contact than boys. This replicates previous studies showing a female superiority in sociality more broadly, and eye contact in particular.  The amount of eye contact varied quadratically with foetal testosterone level when data from both sexes was examined together, and when the data for the boys was examined alone. This suggests that foetal
testosterone may shape the neural mechanisms underlying social development

One critique*** of that study:

The first study aimed to relate aT with eye contact at 12 months of age (Lutchmaya, Baron-Cohen, and Ragatt 2002a). The infant, in the company of both a parent and the experimenter, was given toys to play with, and eye contact frequency with the parent was used as the dependent variable. (While contact frequency and contact duration were correlated, the first was considered, without an explanation, a more accurate measure than the second; see 329.) The authors considered eye contact a “marker of social development” (328), but did not explain in what sense, apart from noting that autistic individuals show fewer eye contacts than individuals without autism. However, in this particular experimental situation, in which the infants interacted with a stranger (the experimenter), eye contact with the parent could reflect shyness, fear, or concern. Indeed, given that the experimenter was a stranger, arguably a better measure of social competence would be eye contact with the experimenter.

Lutchmaya and colleagues found a higher frequency of eye contact in females than males. They also found no relationship between aT and eye contact frequency in females. This result was explained by the authors in terms of small sample size (n = 30), but their data, as shown in the scatterplot, shows no relationship between the two measures.

In males (n = 41), the function was quadratic, which means that a high frequency of eye contact was observed in males with low and high levels of aT. This result runs contrary to the E/S hypothesis, according to which higher levels of fT should be associated with low frequency of eye contact (as in autism). A number of methodological concerns can also be raised, especially the apparent lack of any attempt to either control or monitor the gaze behavior of either parents or the experimenter. There was also no information regarding whether the experimenter was blind to either the experimental hypothesis, or the infant’s aT status. Moreover, each infant was filmed for “approximately” 20 minutes (328); as a result, the frequency of eye contact could have been overestimated in some infants or underestimated in others due to an apparently variable length of observation time.

The term aT stands for amniotic fluid testosterone.  Given that the number of eye contacts for boys in that twenty-minute video ranged from 3.0 to 46.2 times and the number for girls ranged from 3.8 to 55 times the question about the exact length of the video is not pettiness.

I include that long quote not because it would be important to show what might be wrong in one of several studies but because  the abbreviated conclusions of researchers do not necessarily reflect everything we should learn about their studies, and because it can be hard to determine which practical measures are linked to empathizing and which measures are not.   
As Grossi and Fine note in their chapter on fT and Baron-Cohen's theory, whether, say, vocabulary size is correlated with empathizing or systemizing or both is a difficult question to answer.  In one sense learning vocabulary is essential for empathizing properly in humans, in another sense learning vocabulary is like collecting words, and Baron-Cohen himself argues that collecting is a systemizing trait.  And language certainly is a system.

I recommend that Grossi and Fine chapter and its appendix for anyone who is interested in criticism of  Baron-Cohen's group's fT studies.  Better still, buy the book that includes it.
What's weird about the debates on biological sex differences is their whack-a-mole nature.  The conclusions about some gender differences (though it can be unclear which differences being innate remain the same, the theories or studies supporting those conclusions, on the other hand, do not****.  It's a bit like that game of whack-a-mole:

An arcade game in which players use a mallet to hit toy moles, which appear at random, back into their holes:
And yes, holding the mallet in readiness can be an equally instinctive reaction, though at least it's in self-defense.  Flawed or premature theories about biological sex differences have pretty high real-world costs.  To return to that quote at the beginning of the post,  we should all be concerned about studies which roughly equate the ability to think about systems and being a nerdy guy, because such flawed beliefs do matter.


*I write "almost" because it's hard to imagine a person with zero ability in both.  Indeed, it's hard to see how anyone could survive without systemizing skills because that seems equivalent to not understanding cause-effect chains.  As I note in the PS to this post, the definition of systemizing in Baron-Cohen's work ties it to examples which are about male interests and hobbies and fails to note that systems exist everywhere, including in such traditionally female areas as cooking, sewing and knitting.

**This is the only study I was able to locate (so far) which uses a larger sample of children but doesn't include any of the things the above quote mentions.

***Grossi, G., & Fine, C. (2012). The role of fetal testosterone in the development of “the essential difference” between the sexes: Some essential issues. In R. Bluhm, A. Jacobson, and H. Maibom (Eds.), Neurofeminism: Issues at the Intersection of Feminist Theory and Cognitive Science. Palgrave-Macmillan

The chapter is available here (and the Appendix from p.33 on) but without the list of references.

****For instance, we women have been deemed to fit certain sex roles and not others because of our smaller average brain size, because of assumed sex differences in brain lateralization, because of different proportions of gray and white matter in the brains of men and women, because of the way parts of the brain are argued to communicate in men and women, because of the impact of the Y chromosome or the lack of it and because of fetal testosterone.  Though the various explanations don't have to be mutually exclusive in theory, in practice one theory is supported until someone hits it with a mallet, then another theory takes its place.

That's not to argue that we couldn't one day find a theory that can withstand the mallet (though it's quite likely to include a much more complicated view than nature vs. nurture as the explanatory mechanism).  But it does suggest that the search for that theory starts from the desired conclusions.  Which then suggests to me that we are going to have these debates forever, sigh.