Sex and the Brain
Gender differences in cognition and perception are real
Posted Feb 20, 2018
John Gray, author of Men Are from Mars, Women Are from Venus, argues that the two sexes have fundamentally different ways of thinking and communicating. Since a growing body of research supports Gray’s premise— revealing sex differences in everything from problem solving to play behavior—it seems natural to ask whether male and female brains are also fundamentally different.
Indeed, scientists studying the nervous systems of men and women have found physiological and anatomical variations that could explain some gender differences in cognition and behavior.
For example, neuroimaging studies show that women tend to use both sides of their brains for processing language, while men typically employ only the left side. These results correlate with clinical findings that females are less likely than males to suffer speech impairments after a stroke in the left cerebral hemisphere.
Some of the largest dissimilarities between the sexes are in spatial and verbal problem solving. By giving the following spatial and verbal tests to people at your next gathering of more than 10 men and 10 women, you’ll learn whether you and your friends fit the general pattern.
I want to emphasize that statistical gender differences do not predict what any individual's cognitive attributes might be. I have known many women and men with off-the-charts spatial ability and verbal ability respectively.
Each of the figures numbered 1 through 10 below is a rotated version of either the template marked L (for left) or R (for right). Get a piece of paper and take 60 seconds and mark down an L or an R for each of the numbered figures, denoting which template that figure represents. At the bottom of the page, see how many you got right. The closer you got to a perfect 10, the greater your space-relations ability. Incidentally, this test also provides a rough estimate of your brain’s “biological age,” as our ability to perform spatial transformations in our head slows down when we get older.
In 30 seconds, write down as many four-letter words as you can think of that begin with “V.”
Now take another 30 seconds and see how many five-letter words you can write down that begin with “P” (no plurals, please), then add this total to the number of four-letter V words you remembered.
Average the scores on each experiment for males and females. Most likely, the men’s average score will be higher than the women’s for the first experiment, while the reverse will be true for the second experiment. When I gave these tests to coworkers, men averaged eight correct on the spatial test and six on the verbal task, while women got average scores of five and eight, respectively. Your results may be different because variations within a sex on verbal and spatial abilities are usually less than variations between sexes, so experiments have to be run on large groups (over 100 people) to achieve differences of consistent magnitudes.
Researchers continue to search for gender differences in the brain that might explain these variations in verbal and spatial problem solving.
Murat Yucel and colleagues of Monash University found that male cerebral corticies, are, on average, more left-right asymmetric than those of females, with right hemispheres in men (where spatial processing is believed to occur) having more brain volume than left. J.J. Kulynych et al at the U.S. National Institute of Mental Health also found that planum temporale PT, a region associated with language functioning was more asymmetrical in males than in females, with Male left hemisphere PT volumes being larger, on average, the right hemisphere PT volumes.
How such gender difference in brain anatomy arise in the first place remains a matter of speculation. Research on brain plasticity strongly suggests that brain tissue resembles muscle tissue in that the more brain tissue is exercised, the larger it grows. Perhaps males, from an early age--on average-- employ spatial skills more than verbal skills, while the reverse is true-- on average--for women. Green and colleagues at University College London have found that verbal exercise can indeed influence local brain volumes. The famous London cab driver driver study, which demonstrated larger than normal hippocampi in drivers who had to master complex spatial memory tasks, indicates that brain plasticity also plays a role in spatial skills.
Although the anatomical physiological substrates gender differences in spatial and verbal abilities are still poorly understood, some neuroscientists think they may know why males and females evolved separate sets of skills in the first place. Dr. David Geary of the University of Missouri, for instance, theorizes that in primitive societies males with well-developed spatial skills could navigate and hunt better than those with lesser abilities and so were more likely to reproduce and raise healthy offspring. Early human females, on the other hand, relied on interpersonal skills, including verbal ability, to attract a worthy mate and maintain important relationships after mating.
Understanding male-female differences in cognitive skills could be of benefit to teachers who want to customize the approach they take with individual students, or --given what we know about brain plasticity-- to put special emphasis on beefing up verbal and spatial skills respectively in the two sexes.
1R 2L 3R 4R 5L 6L 7R 8L 9R 10L
My new book, Brain Safari, has other quick tests to assess individual differences.