Scientists now debate how much, rather than whether, biology contributes to sex differences in cognition.

LONDON – A prevalent understanding, particularly in the 1980s, was that boys and girls are born cognitively the same. It was the way parents and society treated them that made them different.

Since then, a preponderance of research has called this belief into question. The majority of today's psychologists agree that some of the differences exhibited by male and female brains are innate.

"We do socialize our boys and girls differently, but the contribution of biology is not zero," said Diane Halpern, a professor of psychology at Claremont McKenna College in California, who has been studying cognitive gender differences for 25 years. Halpern was a keynote speaker at the British Psychological Society Annual Conference here last Thursday (April 19).

How much, rather than whether, biology contributes is where the unusually heated debate is now focused, she said.

Differences confirmed (so far)

Some of the many gender differences that float in popular consciousness have more support than others.

The ones that have been consistently found across cultures, life spans and even across species are the most likely — but by no means guaranteed — to have some biological underpinning.

Across age groups, species and nations, males tend to be better at various spatial skills. For example, male dominance in rotating an object in their minds, a quite large difference that has been reliably found for the last 35 years, has recently been documented in infants as young as 3 months old. Similarly, on average, males across cultures and species are better at judging angle orientation and navigating by cardinal direction. [10 Surprising Facts About the Male Brain]

Females, on the other hand, tend to have more verbal fluency and greater memory for objects — that is, "they are better at remembering where things are," Halpern said during her talk. Women and females from other species are more likely to navigate by using landmarks than cardinal direction.

"But you can get there using both," Halpern told LiveScience, pointing out that having different skills does not mean that men and women have different levels of intelligence. "There is not a smarter sex," she said.

In general, across a variety of tests, differences seem to fall particularly at the tails of distribution curves, with more males doing very poorly and more males doing exceedingly well.

Differences that vary

It has been overreported that boys tend to do better at math while girls often excel at reading and writing. In truth, the degree of difference is context-dependent.

In school, girls tend to do better in all subjects, albeit by only about a quarter grade on a four-point scale, Halpern said, citing U.S.-focused research. Boys, on the other hand, tend to excel at tests that focus on areas outside their school's curriculum, she said.

Whether these findings mean schools are biased against boys, standardized tests are biased against girls, or nothing of the sort are among the unanswered questions that rage through psychology, education systems and parenting circles today.

And society does play a big role — just not always with the expected results.

In more gender-equal societies, "the male advantage in math virtually disappears," Halpern said, but other differences grow. When given more equal encouragement and access to education, on average, girls become even better at reading than boys and boys further outstrip girls in visual-spatial tasks.

Economics also matter. "Being poor is not good for anyone's cognitive development," Halpern said.

While the disadvantage may be staggering in the poorest nations, it is true in developed countries as well. Halpern explained that while women outnumber men in college, it is primarily men from lower socio-economic brackets that are not getting degrees. [6 Gender Myths Busted]

Losing talent

So, if neither sex is more intelligent, why are we so stratified by adulthood? Why, for example, are more than 90 percent of CEOs male and more than 90 percent of secretaries female?

As long as women are doing most of the caretaking jobsin society, Halpern told LiveScience, such as taking care of young and elderly loved ones, they are going to occupy wage-earning jobs that require less time. (In addition to being a research psychologist, Halpern was the founding director of the Berger Institute for Work, Family and Children.)

There is also an issue of interest, she said, in that many young women may not realize that being, say, an engineer can also be a "helping" job.

As a society, we are not only losing talented women from the workplace, she added, we are also losing talented men in the domestic front. Men can be excellent caregivers, and numerous studies have shown the importance of fathering for children.

"We can't have equality in work, if we don't have equality in the home," she said.