Friday, 22 June 2012

Brain Scams

To help with this post, I have taken the liberty of allowing the respected neuroscientist, Cordelia Fine, to offer us a few helpful hints when ''considering incorporating neuroscientific findings into an article about gender:

1. Unless you have a time machine and have visited a future in which neuroscientists can make reverse inferences without the nagging anxieties that keep the more thoughtful of them awake at night, do not suggest that parents or teachers treat boys and girls differently because of differences observed in their brains.

2. If you don't know what a reverse inference is..." ... Google will provide you with the definition: Reasoning from the outcome of a dependent variable to infer the state of an independent variable (or an intervening unobservable variable).

3. "Exercise extreme caution when making the perilous leap from brain structure to psychological function.

4. Don't make stuff up."

So here it is: my article about gender and the brain. I will endeavour to follow our distinguished neuroscientist's top tips. I am not the press, I do not gain anything from making things up.

Let's get a few of our faaave myths out of the way:

- Women use the left side of their brain more, while men use the right side more.

The media LOVE this one. Scans reveal this, scans reveal that. I'll tell you, from the very piece of research the media is 'quoting', what scans revealed:

''Rightward hemispheric asymmetry was found in the brains of 14 of 25 heterosexual males and 11 of 20 homosexual females, but in only 13 of 25 heterosexual females and 10 of 20 homosexual males."*

So in a TINY sample of 25 heterosexual and only 20 homosexual men and women (why is the sample size less for homosexuals? Someone please clarify this for me), scans actually say that it's pretty much 50/50. Professor Mark Liberman scrutinised this study in his paper 'Annals of Essentialism: sexual orientation and rhetorical asymmetry' and found, well, pretty much the same as not-a-professional I did; that even in an extremely small sample, there was great overlap between men and woman. He calmly explains (as only an aged Prof. can), ''I'm not arguing that this paper's results are scientifically meaningless, just that they don't mean what nearly everyone reading the media coverage — and the PNAS press release — thinks they mean."

My contribution to this debate: if it turns out that women do use the right side of their brain more, I have no doubt that this side will be forever associated with empathy and compassion. If it ever transpires that men do, in fact, use the right side of their brain more than women, I fully anticipate a fully-fledged media shift from empathy to aggression. If, however, it remains that both genders seem to use both sides pretty equally, with vast overlaps... Well, unless someone at The Daily Mail reads my blog and likes what they see, I don't foresee any immediate change to our current interpretation.

- Females have a larger corpus callosum, connecting both hemispheres of the brain

If you are unfamiliar with the term 'corpus callosum', you may be more familiar with 'grey and white matter'. People like to talk about how women have more grey matter than men, and how their white matter is concentrated (in their larger corpus callosum).

Many scientists like to interpret this as: when a female 'knows what to do, she's not as worried as a man might be about proving it with data'.**

A good question here might be, why should arriving at a solution to a problem through an analysis of data and proof require any less integration between hemispheres? Where does the assumption, that a lateralised brain will be worse at multi-tasking, come from?

Ironically, an experiment on chicks proved quite the opposite: that chicks with more lateralised brains were better at simultaneously pecking for food grains and looking out for predators.*** Now I'm personally a little sceptical when considering the nuanced neurological effects of a hormone, on an animal compared to a human (as was made quite obvious re. rats in my previous post), but I'm a little more convinced about the neurological effect of something, how can I put this? Entirely neurological.

Before I become too biased however, I intend to do some more research into both hormones and neurology, to assess, with how much validity, we can apply results obtained from less neurologically advanced animals to ourselves. Moving on...

... The really funny thing about this myth is, we're not even sure women actually have the larger corpus callosum. Assuming we do, it must mean we're better at multi-tasking and empathising. If it turns out that we don't, I expect it will be because we're not as logical or rational as men. What do you think?

The first piece of evidence to suggest that women do have the larger corpus callosum, was published in 1982.**** (Sorry, the asterisks are getting a little ridiculous but there's no referencing tool on blogger). In 1997, two scientists conducted a review of all the experiments re. the size of the corpus callosum. They discounted this experiment, and others of it's ilk, because it did not meet 'conventional scientific standards'. That's not to say they weren't equally critical of experiments falling to the other side of the debate; they scrutinised all the available research fairly and concluded that 'our review of a substantial literature on the human corpus callosum does not support any sex-related difference in the size or shape of the splenium, whether or not adjustments are made for whole brain or cortex size'.*****

It is important to note that no further research between 1997 and present day, has been able to prove otherwise.

It would be very convenient of me, if I neglected to mention a few experiments that may have uncovered legitimate gender differences. Physiological imaging has, undeniably I think, shown that women's brains contain more nerve cells and cellular connections than male brains.****** What science does, but what the media fails to do, is explain why this might be...

- Neurological differences between men and women are biological

You would assume so, wouldn't you? I would assume so anyway. I'm not sure why, seeing as everything us humans experience is neurological. I mean, pretty much everything is linked to our brain, isn't it? Whether it's biological or sociological, we're processing it all through the same piece of apparatus.

So when gender differences come up, valid or doubtful, significant or insignificant, we all assume that they are biological. It helps us express how alien we find the opposite sex. Imagine, for a moment, that the roles our genders have predominantly fallen in to, might have an impact on how our brains form, how connections are made, and areas expanded. Then take a look at this experiment conducted on London cab drivers:

''As all Londoners know, taxi drivers in London are required to learn The Knowledge, a thorough mental map of the city. The cab drivers in this test had spent an average of two years doing The Knowledge, and so had spent a significant amount of time building up their spatial memory. And when the structures of their brains were compared to those of a control group, it was seen that part of the brain, the posterior hippocampus, was larger among cab drivers than among the other men. The researchers therefore concluded that the posterior hippocampus was the area of the brain they relied on to store this encyclopaedic spatial understanding of London's streets. Those who support biological determinism might have jumped in to argue that it was the greater size of this part of the brain that had decided the men in favour of this career, but the researchers also found that the longer these men had been cab drivers, the bigger the posterior hippocampus, so that as they went on adding detail to their knowledge of the city, their grey matter grew. Since the volume of grey matter in this part of the brain correlated with the amount of time spent as a taxi driver, this suggested that the human brain can change physically in response to its environment, even during adulthood."*******

The brain we're born with develops from birth, right? In response to our experiences, right? So, quite viably, it can respond even to the stereotypes that we're reduced to. Certainly explains how, in the UK and USA where we believe women are worse at maths, women do indeed perform less well than men do. Did you know, women in the UK and the USA achieve some of the worst maths results in the entire world? Biological? I highly doubt it. ********

* Proceedings of the National Academy of Sciences: Ivanka Savic and Per Lindström, "PET and MRI show differences in cerebral asymmetry and functional connectivity between homo- and heterosexual subjects", PNAS, (2008).
** Gurian and Annis (2008)
*** Rogers, Zucca & Vallortigara, (2004)
**** C Lacoste-Utamsing & R L Holloway, 'Sexual dimorphism in the human corpus callosum', Science, 216 (1982)
***** K M Bishop & D Wahlsten, ibid, p590
******* N Walter (2010)
******** Nosek et al (2009)

No comments:

Post a Comment