More public schools splitting up boys, girls

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10. "Pseudoscience in Sax on Sex"

http://www.psychologytoday.com/blog/brainstorm/201109/pseudoscience-in-sax-sex

PT blogger cherry-picks science to support single-sex schools

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This is not, however, the message that single-sex school advocate (and Psychology Today blogger), Leonard Sax, has been conveying. In December 2010, he blogged about a PNAS paper by Raznahan et al. which he alleged shows that "sex differences diminish as a function of age" (his emphasis).

To Leonard Sax, this idea is very important. If boys' and girls' brains differ from each other more than adult men's and women's brains differ, it justifies sending boys and girls to different classrooms and teaching them in different ways. Adult men and women may work and govern together, given our highly similar brains, but children aren't ready for this integration, because of their metaphorically pink or blue neural circuits.

As evidence, Sax refers readers to an online movie which is based on Figure 1 of the PNAS paper, but he misinterprets the figure legend. (The movie didn't play for me, and Sax warns readers they may have trouble playing it, but I'm assuming it is the same movie shown in a Wall St. Journal article that repeats Sax's mistaken interpretation, including its faulty caption.)

The figure/movie shows beautiful colorized brains, with cortical areas that are thicker in males shown in a blue-purple color scale, while areas that are thicker in females are shown in white (with no color scale, to avoid confusion with the male-larger color scale). What you see as the images progress from 9 to 22 years of age is that blue/purple areas give way to white areas in the frontal lobe. In other words, during early adolescence, males' gray matter is thicker through much of the cortex, but in adulthood, females' frontal gray matter is thicker, while males' gray matter remains thicker in other cortical lobes.

But Sax misread the figure legend! He states that the white coloring shows areas of no sex difference in cortical thickness, when in fact, the white depicts areas that are thicker in females. So despite what Sax wrote in his Psychology Today blog, the paper by Raznahan et al. does not demonstrate that sex differences are globally greater in childhood and diminish in adults.