Last December, a major study was published by the Proceedings of the National Academy of Sciences on sex differences in neural connectivity. The authors of the study used neuroimaging techniques to examine the brain of nearly 1000 participants, roughly 50/50 male and female. The participants ranged in age from 8-22. The results of the study revealed that male brains showed greater connectivity within each hemisphere while female brains showed more connectivity across brain hemispheres. In lay terms, the results indicate, according to the authors of the study, that men would generally be better at activities, such as sports, due to greater spatial awareness and coordination. Further, women would generally be better at activities grounded in socializing and memory. The authors go on to suggest that the results denote a trajectory of brain functioning between males and females, because the ages of participants ranged from childhood into emerging adulthood. They used these results to emphasize the structure of the brain as being inherently different between sexes, which will be important to keep in mind while reading below.
The results of the study made their way into mainstream media and began a firestorm of debate. News and popular blogs began reporting the initial results declaring, in essence, “Men are better at reading maps and women are the great multi-taskers we always thought they were.” The summary of the study continued to be diluted by news outlets from both sides of the aisle, including the Guardian and the Wall Street Journal. Luckily, neuroscientist Cordelia Fine and journalist Kat Stoeffel came to the rescue and laid down some real science for us. Issues that confound the conclusions of the study include:
· The influence of brain size
· The fact that the participants in the study were a subset of a larger study that found “trivially small” sex differences in psychological skills, including spatial processing and social cognition
· The absence of consideration of gendered experiences, such as personal hobbies
· The absence of information on the origin of these differences
· The fact that the study did not actually test for the activities it claimed men or women would be better at
· The results were statistically significant but are not supported by other neuroscience research actually measuring these psychological abilities
At this point, I am reminded of what a professor once told my class about the correlation between height and intelligence – even though it’s significant, it is also not meaningful.
The aspect of this study I find the most disappointing is how easy it is to poke holes in the methodology and conclusions. Any person with a rudimentary understanding of gender socialization could easily negate these conclusions. We already know that children learn colors and toys associated with gender in the first few years of life. Even an 8-year-old child has already been in enrolled in soccer, ballet, plays ‘school’ or ‘house’ with friends, or reenacts a superhero show at recess. They are not the blank slate of sex differences assumed to be the case.
In addition, critical publications in recent years have underscored the tendency of behavioral scientists and those using neuroimaging techniques to select specific cases of data and use convoluted statistical analyses to foster and overstate their conclusions. Full disclosure: I have not examined the statistical analyses of the study in question. However, this desire to manifest statistical significance for whatever reason (I would speculate to get published) is noteworthy.
Upon discussion of these findings, my friend and colleague responded to me that “science is amoral.” Checkmate, right? I mean, the speed of light is the same meters per second whether I’m turning on lights in a hospital or in a prison. But, the concept of science is a human construct, and we create the study, the methodology, and report the results. We have Institutional Review Boards, because even though there are queries we want to entertain, we have decided as a field to take a moral high road and not conduct experiments that cause harm to others.
So, how can we really find out if there are hard-wired sex differences? At first, I thought, “Who could we look at who has not been affected by gender socialization?” Newborns. Newborns have been the participants of experiments related to sex differences. For the most part, the jury is still out, but the evidence thus far leans toward no differences aside from brain size. Further, the issues discussed above with regard to statistical significance and publication muddle what we really know. Studies finding no differences are not “interesting” so we never find out about them.
Generally speaking, we do have some evidence of how the environment changes the brain. Specifically, interventions in psychotherapy alter intensity of activity in certain regions of the brain. Also, studies of individuals who meditate suggest that connections in the medial prefrontal cortex change with increasing meditation. If these processes change intensity and connectivity, then could repeatedly playing ‘teacher’ influence the structure of the brain?
But, what about what we learned sex education? You know, with the onset of puberty, we excrete certain hormones that serve as the catalyst for changes in and on our bodies. However, testosterone, estrogen, and progesterone are produced, provided there are no problems with hormone production, in both sexes. Further, diet and exercise also influence the levels of these hormones in the body. Thus, even though the foundations are laid for sex differences, the expression of these differences is incredibly complex.
My hypothesis is that finding evidence for hard-wired, unmalleable sex differences in the brain in the absence of gender socialization is an untestable hypothesis in the current state of science. Now, I am not arguing that the consideration of sex and gender differences is not a worthwhile cause to contemplate. However, there are so many within group differences that get neglected when we present over-simplified research and reinforce gender binaries. At this point, my opinion on this matter is that with the state of neuroimaging techniques and pervasive research on gender socialization, finding evidence for gender differences in hard-wiring of the brain is like chasing a windmill.
Written by Teresa Young