On the Science of Changing Sex

(Cherry) Picking The Transgender Brain

Posted in Brain Sex, Editorial by Kay Brown on May 31, 2018

27867072_1811649452220144_4426664495691531655_nOr, How To Ignore Brain Science That Tells A Story You Don’t Like

Psychology graduate student and computer coding instructor Sophie Searcy, responding to the recent over-hyped study of transkids brains (mentioned in previous post) has produced an excellent example of transgender brain science cherry picking.  The one that REALLY stands out as egregious is that she cites the Joel study that she claims… well… let Searcy tell it,

“Indeed, not only is the existing literature on sex differences in brain imaging likely biased, but recent work does significant damage to the idea that there are distinct, separate, “male brains” and “female brains” at all. A research group led by Daphna Joel summarizes the findings of their meta-analysis that included brain images from 1,400 participants: “Brains with features that are consistently at one end of the ‘maleness-femaleness’ continuum are rare. Rather, most brains are comprised of unique ‘mosaics’ of features, some more common in females compared with males, some more common in males compared with females, and some common in both females and males.”

So what’s the problem?  Well, it’s dishonest cherry picking to cite a study that another group (Chekrouda, et. al) responded in the same journal with a similar study that showed that if Joel had conducted a multi-variate analysis they would have found out that male and female brains scans WERE in fact differentiable by a mathematical model at 93% accuracy.  As I explained previously I did a bit of calculation and found much to my amazement, that to “guess” the sex of the brain to 93% accuracy means that the effect size (Cohen’s d) would, if it were a single dimorphic feature, be a whopping 3.0 !!!!  That’s an over the top value.  Thus, as we get better imaging tools to see the fine details, we are learning that the human brain, in terms of multivariate statistics of multiple measurements at all points of the brain, is in fact extremely sexually dimorphic.  The problem is that no one area is all that dimorphic, but in aggregate, they are quite dimorphic.  That is to say, if one area is slightly dimorphic, giving a small statistical clue as to the sex of the individual, and a second area is also slightly dimorphic, giving a small clue as the sex of the individual, the two can be used together to give a medium-sized clue to increase the accuracy… and with many many areas, each additively pointing towards one sex or the other, the accuracy gets quite good.

Searcy should have noticed this second paper which shows that Joel’s paper does NOT debunk the hypothesis that discernible male and female brains exist.

So, why did she write this article and cherry pick the science?  Perhaps we can get a clue from another statement she makes,

“In a 2017 paper, Bakker and colleagues summarized similar work on adults as finding that “adults with GD [gender dysphoria] differ from both cis-gender [sic] men and women.” In other words, adult trans brains appear to be distinct from adult cis brains of either sex. Should trans adults be worried? In that same paper, the researchers actually found mixed results for adolescents. They looked at nine brain regions each for trans girls and trans boys. Of those 18 regions, the researchers reported significant differences in only four out of 18 areas. One area where trans girls differ from both cis girls and cis boys, two areas where trans girls are similar to cis girls, and one area where trans boys are similar to cis boys. What does this mixed bag suggest if we are to believe that trans brains must be similar to cis brains in order to be seen as legitimately transgender?

Ummm… this result is in complete agreement with another hypothesis that many transwomen find uncomfortable, one made by Ray Blanchard, in which he hypothesized that late transitioning transwomen would have brain structure differences from both men and women that would NOT be sexually dimorphic; while young (“homosexual”) transsexuals would show shifts in sexually dimorphic structures toward female morphologies.  There was an earlier review of previous studies (which I also wrote a post about) that had shown that hypothesis to be supported.

Searcy is likely to have written her article in an attempt to discount the growing evidence from transgender brain scan research that shows that the two type taxonomy for transwomen is supported.  Where once older transitioning transwomen cherry picked the brain structure research in an attempt to spin it such that all transwomen had female brains.  She is spinning the science to lead us to believe that brain structure research is unimportant and should be ignored, first by saying that there is no brain structure sexual dimorphism of any consequence and then say that what differences between transgender folk and nontransfolk is unimportant anyway.  I believe it represents a growing fear by autogynephilic transwomen that the brain scan science will undermine their own identity as transwomen if the public were to become aware of what the evidence means.

Further Reading:

Essay on Chekrouda paper

Essay on Transgender Brain Sex Review

Essay on Cherry Picking Brain Research to Prove All Transwomen Have Female Brains

References:

https://www.them.us/story/brain-scans-transgender-identity

Chekrouda, et al., “Patterns in the human brain mosaic discriminate
males from females”  http://www.pnas.org/content/113/14/E1968.full.pdf

 

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