Sorting through the noise
Fig. 1 from Shaywitz et al. (1995), downloaded from
Nature.com,shows a composite of 19 male brains (left) vs.
19 female brains (right)during phonological processing. This
represents a subtraction of results from two different tests. Shaywitz et al. (1995) used functional magnetic resonance imaging (fMRI) to test the hypothesis that language tasks are more lateralized (i.e. activity is more on one side of the brain) in males than in females.) The researchers used four language-based tasks to test brain activation, and then used subtraction to isolate specific types of brain activations, such as by subtracting the results of a rhyming task from a semantic category task to isolate lexical semantic processing. Shaywitz et al's experiment demonstrates that it may be possible to isolate specific brain functions from a complicated set of tasks such as processing language. Thomsen et al (2000) used a similar subtraction strategy to examine mental rotation of a 3-D object. In Thomsen et al's experiment, males and females performed equally well, unlike in other experiments using a similar task, which had shown that males had greater success in this area.
This sort of subtraction may be pivotal to understanding gender differences in brain function, since (as Cahill points out), identical performance does not necessarily mean identical process. Men and women may perform equally well on a task that they are performing using different cognitive strategies and/or brain regions, but by measuring performance alone, these differences remain hidden.
One of the things I did when I first started to transition was attempt to increase my ability with male-stereotyped brain tasks. I would attempt to rotate 3-D objects in my head instead of reading a book, or try to read maps without orienting them the way I was facing. I do think that the practice helped, but it amuses and saddens me how much I wanted to excel at these tasks. Even now, I fight the urge to constantly test myself -- to make sure that I'm masculine enough to deserve the life I enjoy so much. I think every man wonders from time to time if he's "man enough". I just get a little extra doubt.