Top: male brain networks • Bottom: female brain networks
Average findings from the University of Pennsylvania study
Images ©study authors

“At any given moment, a woman is likely to be using her whole brain while a man is using half of his. Men are more likely to be right-brained (more intuitive) or left-brained (more logical) than women.”
—Ruben Gur, neuropsychologist and one of the study authors

A just-published study of the brain functionality of 949 young people shows striking differences in brain wiring between men and women. The authors of the study suggest that male brains are biologically structured to facilitate connectivity between perception and coordinated action (motor and spatial abilities), whereas female brains are designed to facilitate communication between analytical and intuitive processing modes (memory, social adeptness, multi-tasking).

The study of 428 males and 521 females aged 8-22 was conducted by ten colleagues at the University of Pennsylvania and published in the Proceedings of the National Academy of Sciences. They used a technique called “diffusion tensor imaging” (DTI), which scans the paths travelled by water molecules around the brain.

“The maps show us a stark difference in the architecture of the human brain that helps provide a potential neural basis as to why men excel at certain tasks and women at others.”
—Ragini Verma, researcher

The story is making a big splash in the press and in social media. It is a notable study, however, the main interpretation the researchers and the media seem to be taking from the study is that gender differences are biologically determined. I found such a conclusion very puzzling, because the study results themselves show that differences in brain wiring are not congenital!

The study showed that boys and girls are born with similar connectivity, and that differences in brain pathways between the genders begin to manifest at about 13 years of age, and diverge even further at 17. The study authors attribute this to the time sex begins to become important in a person’s life. I suppose that means the time hormones begin to kick in? But, of course I wondered if the differences emerge during the teenage years because that is about the age that gender socialization really begins to manifest.

Then Kathryn Stillings, our editor, found this article by science writer of the year Robin McKie. Robin explains that the study’s findings actually disprove the authors’ interpretations and reinforce the view that gender differences are the result of acculturation.

“Yes, men and women probably do have differently wired brains, but there is little convincing evidence to suggest these variations are caused by anything other than cultural factors. Verma’s results showed that the neuronal connectivity differences between the sexes increased with the age of her subjects. Such a finding is entirely consistent with the idea that cultural factors are driving changes in the brain’s wiring. The longer we live, the more our intellectual biases are exaggerated and intensified by our culture, with cumulative effects on our neurons. In other words, the intellectual differences we observe between the sexes are not the result of different genetic birthrights but are a consequence of what we expect a boy or a girl to be.”
—Robin McKie, The Observer

I trust you’ll read the study and the various interpretations, and draw your own conclusions. Either way, via biological determinism, acculturation/socialization, or a mix of the two, Cultural Detective Women and Men is a terrific package that delves into gender differences in a practical, dynamic way. It combines beautifully with national, religious tradition or generational packages. We trust you will try it out in your work, to help ensure that the broadest spectrum of cognitive skills are accessed for innovation and effectiveness in our organizations and societies.

More on the New Brain Study

The study’s findings show that the dominant connections in the male cerebrum (top left image above) are within either the left or right hemisphere (blue lines), and the dominant connections for females are between hemispheres (bottom left image/orange lines).

In the cerebellum (right-hand images, lower part of brain) it is just the opposite: the average male brain shows connections between hemispheres while the average female brain has dominant connections within hemispheres.

“Forget right-brain or left-brain thinking. What may be more important from a gender standpoint is back-to-front or side-to-side thinking.”
—Stacey Burling, Philly.com

“The strong link with the cerebellum might make men more action oriented, better at tasks that require quick response time or an ‘I-see-and-then-I-do’ attitude. The side-to-side thinking likely boosts women’s memory and social skills and seems designed, the authors said, to combine analytical and intuitive thinking. Communication within the hemisphere facilitates connection between perception and coordinated action,” writes Stacey Burling in her online review of the study in philly.com. Women’s brains “more easily integrate the rational, logical, verbal mode of thinking and the more intuitive, spatial, holistic mode of thinking,” she quotes Gur as saying. “Women’s thinking is likely to be more contextual. Their brains are better connected between their decisions and their memories. For men, memories are memories. Decisions are decisions.”

It is noteworthy that DTI or diffusion tensor imaging provides only indirect measures of structural connectivity and is, therefore, different from the well validated microscopic techniques that show the real anatomy of axonal connections,” says Marco Catani, of London’s Institute of Psychiatry. “Images of the brain derived from diffusion tensor MRI should extreme caution.”

I am curious about the results we’d see of a similar brain study of people older than 22, as I feel we change significantly as we age. This point is echoed by Professor Heidi Johansen-Berg of Oxford University, who attacked the idea that brain connections should be considered as hard-wired. “Connections can change throughout life, in response to experience and learning.” Hopefully the next step of this work will include such a study.

Care to learn more? Click the link above to the abstract of the original study, or read this terrific article from The Atlantic.