Delusions of Gender (24 page)

Yet sometimes the temptation is too much to resist.

Twenty years ago, my mother proposed a neuroscientific model to explain why some brains have an extraordinary capacity for deeply focused thought. Her hypothesis was that ‘[a]ll the blood in your brain rushes to the really clever bits and there’s none left over to warm up the roots.’
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My mother, by the way, is a novelist. Yet her idea, coined as an acerbic marital insult in a work of fiction, shares an important flaw with a suggestion made in a prestigious journal of science. Simon Baron-Cohen and his colleagues, as mentioned earlier, suggested in
Science
that a brain skewed towards local connectivity is ‘compatible with strong systemizing, because systemizing involves a narrow attentional focus to local information, in order to understand each part of a system.’
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Likewise, in the recent book
Why Aren’t More Women in Science?
neuroscientists Ruben and Raquel Gur conjecture that ‘the greater facility of women with interhemispheric communications may attract them to disciplines that require integration rather than detailed scrutiny of narrowly characterised processes.’
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But why, we might ask, should shorter circuits in the brain allow narrower focus in the mind? As McGill University philosopher of science Ian Gold has said, ‘[m] ay as well say hairier body so fuzzier thinker. Or that human beings are capable of fixing fuses because the brain uses electricity.’
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Consider what’s involved in zooming in your attention on, say, a small aspect of the process of photosynthesis. Does only a little bit of the brain get involved because only a little detail is being processed? Or is there – as seems far more likely – activity all over the brain as distracting information is suppressed, the inner voice formulates ideas and poses questions, visual stimuli are processed, motion is imagined and information is retrieved from memory?
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In truth, if it was the male brain that seemed to be more long-range, we could easily concoct a plausible hypothesis to explain
why this enhances their systemising skills. And this is the problem: the obscurity of the relationship between brain structure and psychological function means that just-so stories can be all too easily written and rewritten. Do you find that your male participants are actually
less
lateralised on a spatial problem? Not to worry! As the contradictory data come in, researchers can draw on both the hypothesis that men are better at mental rotation because they use just one hemisphere, as well as the completely contrary hypothesis that men are better at mental rotation because they use
both
hemispheres. So flexible is the theoretical arrangement that researchers can even present these opposing hypotheses, quite without embarrassment, within the very same article.
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Likewise, Gur and his colleagues happily tinker with the longstanding idea that it is males’ more lateralised spatial processing that underlies their superiority on mental rotation tasks. They found that performance on two spatial tasks correlated with the volume of interconnecting white matter in the brain.
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White matter is made up of the axons, insulated for speed of travel of the electrical signal by the white fat myelin, which communicate between distant brain regions. ‘When we looked at the top performers for spatial tasks in our study … there were nine men and only one woman,’ Gur explained for the
Science Daily
news release. ‘Of these nine men, seven [actually, it was six] had greater white-matter volumes than any of the women in the study.’
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Now, we’re talking about ten people here – hardly a sample size on which to base sweeping generalisations about the sexes. It’s also, as psychologists well know, dangerous to assume that correlation means causation. Further, in the scientific article itself, Gur cautions that the ‘correlations could be spurious and should be interpreted with extreme caution.’
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And they really could be spurious, given that 1 in 20 ‘significant’ results occur by chance, and the researchers tested for thirty-six relationships. Of course, we don’t know who decided that this caveat was not worth mentioning in the report designed for public consumption. But despite all this, Gur goes on to suggest to
Science Daily
that ‘in order to be a super performer in that area, one needs more
white matter than exists in most female brains.’ Following up this line of argument in their chapter in
Why Aren’t More Women in Science?
the Gurs conjecture that ‘[t]he requirement of large volume of WM [white matter] for complex spatial processing may be an obstacle in some branches of mathematics and physics.’
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This, they suggest, is because men’s greater white matter volumes enable better within-hemisphere processing.

But meanwhile, back in the functional neuroimaging lab, the Gurs and their colleagues have found that in some regions of the brain men show more
bilateral
activation than women while performing spatial tasks. They therefore suggest a ‘reformulation’ of the spotlight hypothesis, namely, ‘that optimal performance requires both unilateral activation in primary regions, left for verbal and right for spatial tasks, and bilateral activation in associated regions.’
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Well, maybe they are right to now emphasise the importance of participation from both hemispheres. Interestingly, researchers who study people with exceptional talent in mathematics argue that enhanced interaction
between
the hemispheres – supposedly a female brain characteristic – is a special feature of the mathematically gifted brain.
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But maybe, just until such a time as we have a somewhat firmer grasp of how the structural properties of the brain relate to complex cognition, the Gurs should stick to the lower-maintenance hypothesis that optimal performance requires whatever features of the brain happen to be observed in males.
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This kind of theoretical U-turn has always beset the neuroscience of sex differences. For example, in the nineteenth century, when the seat of the intellect was thought to reside in the frontal lobes, careful observation of male and female brains revealed that this region appeared both larger and more complexly structured in males, while the parietal lobes were better developed in women. Yet when scientific thought came to the opinion that it was instead the parietal lobes that furnished powers of abstract intellectual thought, subsequent observations revealed that the parietal lobes were more developed in the male, after all.
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With startling insight, Havelock Ellis, the author of a comprehensive
late-nineteenth-century review of sexual science, described these earlier erroneous observations as ‘inevitable’:

It was firmly believed that the frontal region is the seat of all the highest and most abstract intellectual processes, and if on examining a dozen or two brains an anatomist found himself landed in the conclusion that the frontal region is relatively larger in women, the probability is that he would feel he had reached a conclusion that was absurd. It may, indeed, be said that it is only since it has become known that the frontal region of the brain is of greater relative extent in the ape than it is in Man, and has no special connection with the higher intellectual processes, that it has become possible to recognise the fact that that region is relatively more extensive in women.
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Of course, there’s nothing wrong with changing your mind in the light of new evidence about the sexes. But those who are tempted to play this game, by claiming that sex differences in the structure of the brain yield essentially different kinds of minds, should be aware that this sort of flipping seems to be a common part of the process. And, with the benefit of hindsight, it never looks good.

No less care is required when it comes to interpreting differences between the sexes in brain activity. No doubt about it, functional neuroimaging technologies have brought the fresh, modern zing of neuroscience to old stereotypes. Allan and Barbara Pease, for example, purport to demonstrate in their book
Why Men Don’t Listen and Women Can’t Read Maps
the striking sex differences in the sheer volume of brain devoted to emotion processing. A brain diagram of ‘Emotion in men’ shows two blobs in the right hemisphere. As the text explains, emotion in men is highly compartmentalised, meaning that ‘a man can argue logic and words (left brain) and then switch to spatial solutions (right front brain) without becoming emotional about the issue. It’s as if emotion is in a little room of its own’. But in the illustration of
‘Emotion in women’ there are more than a dozen blobs scattered across both hemispheres of the brain. What this means, according to the Peases, is that ‘women’s emotions can switch on simultaneously with most other brain functions’. Or, to call a spade a spade, emotion can cloud all and any of a woman’s mental activities.
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These emotion maps of the male and female brain, the Peases inform readers, are based on fMRI research by neuroscientist Sandra Witelson. In order ‘to locate the position of emotion in the brain’, she used ‘emotionally-charged images that were shown first to the right hemisphere via the left eye and ear and then to the left hemisphere via the right eye and ear.’
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Should readers have both the time and the resources to check out the six Witelson references in the book’s bibliography, they will find only two studies published after functional neuroimaging techniques first began to be substantively put to use by cognitive neuroscientists in the 1980s. One study did not involve brain research (it is a survey of handedness in gay men and women). The other is a comparison of corpus callosum size in right- and mixed-handed people.
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It might also be worth mentioning that it was a postmortem study. Possibly Sandra Witelson really did present her samples of dead brain tissue with emotionally charged images – but if she did, it’s not mentioned in the published report.

It may be that the Peases were referring to functional neuroimaging research published by Sandra Witelson and colleagues in 2004.
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It’s hard to know: this study used PET rather than fMRI; stimuli were presented in the normal two-eyed, two-eared fashion; and the male/female blob tallies and locations are dissimilar to those presented by the Peases. However, this study did at least look at brain activity while men and women performed one of two emotion-matching tasks. The easier task involved deciding which of two faces match the emotion of a third, target, face. The harder task involved deciding which of two faces match the emotion expressed in a voice. According to Susan Pinker’s summary of Witelson’s results, ‘[w]hen women looked at pictures of people’s facial expressions, both cerebral hemispheres were activated and
there was greater activity in the amygdala, the almond-shaped seat of emotion buried deep in the brain. In men, perception of emotion was usually localised in one hemisphere’. Pinker then goes on to suggest that since research also shows that women have a thicker corpus callosum, allowing speedy interhemispheric transmission of information (a claim that, as you will recall from the previous chapter, is under serious scientific dispute), ‘the hardware for women’s processing of emotion seems to take up more space and have a more efficient transportation grid than men’s. Scientists infer that this allows women to process emotion with dispatch.’
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In fact, the researchers found no differences in how quickly men and women performed the tasks. It’s also worth noting that although the statement ‘both cerebral hemispheres were activated’ in women might conjure up an image much like that presented by the Peases, with activity over a generous portion of the female brain, this is not the case. Rather – and take a deep breath before reading on – in the easy task women showed greater activation than men in left fusiform gyrus, right amygdala and left inferior frontal gyrus. In the hard task they showed greater activity in left thalamus, right fusiform gyrus and left anterior cingulate. Men, meanwhile, showed greater activity than women in right medial frontal gyrus and right superior occipital gyrus for the easy task, and in left inferior frontal gyrus and left inferior parietal gyrus for the hard task. Or, rather less technically, women always had two left blobs and one right blob, while men had either two right blobs or two left blobs, depending on the task – painting a rather less striking image of contrast. (Bear in mind, too, that blobs represent
differences
in brain activity, not brain activity per se. If a search for regions activated more in men yields a blob-free left hemisphere, for example, that doesn’t mean that that hemisphere is switched off in men. Rather, it means that the researchers didn’t find any regions in the hemisphere that were activated more in men than in women.)
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Does this complicated-sounding list of brain activations tell us something interesting about gender difference in emotional experience? The researchers, like Pinker, certainly think so. They
conclude that their ‘findings suggest that men tend to modulate their reaction to stimuli, and engage in analysis and association, whereas women tend to draw more on primary emotional reference.’
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(By this they mean that only women find others’ emotions innately arousing.) As you will have already realised, a simpler, and more familiar, way to put the same idea would be to say that men are thinkers and women are feelers.

So does this neuroimaging study simply confirm what everyone already suspected – that ‘men may take a more analytic approach’ to emotion processing while ‘women are more emotionally centred’?
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Or is it possible that these interpretations are, to paraphrase Fausto-Sterling, unwittingly projecting assumptions about gender onto the vast unknown that is the brain?

With the previous chapter’s cautionary tale of premature speculation in mind, it’s worth noting that Witelson’s neuroimaging study compared just eight men with eight women on each task – a modest-sized sample. Could the sex differences in brain activation be spurious? When looking for changes in blood flow between two conditions, researchers search in thousands of tiny sections of the brain (called voxels), and many researchers are now arguing that the threshold commonly set for declaring that a difference is ‘significant’ just isn’t high enough. To illustrate this point, some researchers recently scanned an Atlantic salmon while showing it emotionally charged photographs. The salmon – which, by the way, ‘was not alive at the time of scanning’ – was ‘asked to determine what emotion the individual in the photo must have been experiencing.’ Using standard statistical procedures, they found significant brain activity in one small region of the dead fish’s brain while it performed the empathising task, compared with brain activity during ‘rest’. The researchers conclude not that this particular region of the brain is involved in postmortem piscine empathising, but that the kind of statistical thresholds commonly used in neuroimaging studies (including Witelson’s emotion-matching study) are inadequate because they allow too many spurious results through the net.
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