AP Photo/Daily Kent Stater, Haraz Ghanbari
Courtney Spaller, a fourth grader, holds a
human brain during a Brain Awarness
Program, held March, 2003.

Is Your Brain Male or Female?

November 06, 2009 05:00 PM
by Shannon Firth
Mounting evidence suggests that the differences between male and female brain structure may be more heavily influenced by environment than previously thought.

What Differences in Brain Structure and Activity Really Mean

In 1995 scientists stumbled upon the first evidence of the “functional” difference between the way men and women think while trying to understand what causes reading disorders.
According to The New York Times, when men think, a portion of the left side of their brains becomes active, and when women think, both sides of the brain become active. These findings came on the heels of other psychological research demonstrating that women outperformed men on tests of verbal speed, whereas men have better “spatial skills.”

More recently, Michael Gurian, author of the book “Boys and Girls Learn Differently!” declared, “There are some things boys tend to be better at than girls and vice versa. There is a skill superiority already built into general male and female brain development,” reported the Knoxville News.

While some educators and scientists believe that differences between men and women’s brains are “indisputably biological,” Lise Eliot, a writer for Scientific American, says concluding that these differences are “hardwired” is a mistake. “Simply put, experiences change our brains.”

Peg Nopoulos and Jessica Wood, researchers at the University of Iowa, are just two of a small number of researchers examining male-female brain differences in terms of gender, in addition to biological sex.

They conducted a study in 2008 on the areas of the brain related to “social cognition and interpersonal judgments.” The neuroscientists found that the region of the brain called the straight gyrus (SG), a narrow band at the base of the frontal lobe, was “proportionally larger” by about 10 percent in women than in men, reported Scientific American—even after accounting for the fact that men’s brains are generally 10 percent larger than women’s.

As part of that study, according to Scientific American, subjects were also given a social cognition test. Those who performed best on measures of “interpersonal awareness” on the test, whether male or female, had larger SGs.

In order to determine whether such a difference was “innately programmed,” the same scientists, along with colleague Vesna Merkos, created a similar study for children between 7 and 17 years of age. 

Surprisingly, noted Scientific American, the SG in this second group was larger in boys than in girls. And this time, a smaller SG correlated with better “interpersonal awareness”—the opposite of the results they’d seen in adults.

This could be due to a “reduction in gray matter volume,” or “pruning,” which generally happens to girls’ brains two years earlier than boys’ the scientists considered.

However, in both studies the researchers tested subjects’ “psychological gender” using surveys that measured masculine vs. feminine traits. Tests showed that a larger SG was tied to a “more feminine personality” in adults, while a smaller SG correlated with a more feminine personality in children.

Eliot explained, “[T]he SG appears to reflect a person’s ‘femininity’ better than one’s biological sex: women who are relatively less feminine show a correspondingly smaller SG compared to women who are more feminine, and ditto for men.”

She notes, because gender traits are influenced more by a partiality for typically masculine or feminine interests, jobs and fashion styles than they are by biological sex, it follows that our malleable brains reflect these experiences.

Background: Understanding brain sex differences

“Pink Brain, Blue Brain: How Small Differences Grow Into Troublesome Gaps—And What We Can Do About It,” authored by Eliot, explores how environmental influences, specifically how parents unwittingly treat boys and girls differently, impact the traits and behaviors children develop, reported Newsweek.

In her book she cites a study where adult subjects interacted with infants wearing gender-neutral clothing. The scientists purposely deceived the subjects into thinking one group of boy infants were actually girls and vice versa. The results showed that when adults believed the babies they saw were boys, they described them as “distressed or angry.” And upon seeing babies they thought were girls, subjects said they appeared “happy and socially engaged.”

“How we perceive children—sociable or remote, physically bold or reticent—shapes how we treat them and therefore what experiences we give them … these various experiences produce sex differences in adult behavior and brains,” wrote Judith Begley of Newsweek.

Opinion: How brain research impacts classroom learning

Anne Moir, a British researcher and author who invented the term “brain sex,” argues that male and female brains are “wired differently,” and that these differences should determine how children are taught.

She says children with “boy” brains need more breaks and an opportunity to be physical; she wants to incorporate “play-fighting” into a curriculum she says is too feminine.

Moir is working within the British education system to enact such changes. However, like the University of Iowa scientists, Moir believes that brain sex isn’t always biologically determined and that some brains are “bi-wired.”

She’s even created a test, published here, for identifying gender.

In contrast, teacher Olivia Kuhens, writing for the Knoxville News, said that after reading Gurian’s book she made over her classroom in a way she thought would suit her students’ needs. She seated boys by the windows and placed silly putty and word magnets on the sill. And because Gurian said girls are better multitaskers, she gave them seats by the door and the phone so they could take calls and greet visitors.

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