While science provides support for Harvard President Lawrence Summers’s implication that neurological differences between the sexes exist, Yale scientists said there is little proof that this asymmetry accounts for superior or inferior cognitive aptitudes in science.
Scientists at Yale said personal experience and a growing body of empirical evidence suggest that social expectations — not biology — are responsible for women’s under-representation in university sciences and mathematics.
Studies have shown men and women use different regions of their brains for cognitive tasks. Research by scientists at the Universities of California and New Mexico has shown that use more gray matter and women more white matter.
Dr. Sally Shaywitz, a professor of pediatrics and child study at the University, said her functional MRI studies provide evidence that men tend to use the left side of their brains while women employ more diffuse neural systems involving both sides while performing rhyming tasks. But she said her results are insufficient to draw broad conclusions about the differences between men and women, as discrepancies between individuals of the same sex are often larger than the average differences between sexes.
“It is important to note that not all women in our study were bilateral and that despite the differences in the ways they performed the tasks, men and women performed equally well,” Shaywitz said. “There are so many ways to interpret these things. Sometimes I am concerned we will be caught in the morass of making too much of little differences when we don’t really know what they mean.”
Shaywitz said personal experience has caused her to believe universities have a responsibility to ensure that a successful science career and family life are not mutually exclusive. She said the idea that either men or women are naturally better scientists because of their sex is not viable because scientific skills are so diverse.
“The real question is what is necessary to be successful in science and carry on creative and productive research,” Shaywitz said. “There has been no scientific indication of sex or gender differences there. Being a successful scientist is more than having high test scores.”
But it is important to continue comparing men and women’s brains, she said, because differences do exist, and early imaging studies’ subjects were often all males, making them unreliable for generalizing about the human brain.
Genetics and psychiatry professor Kenneth Kidd said most neuropsychiatric disorders affect males at a higher frequency than females, and young girls develop language abilities much more quickly than boys of the same age.
Studies confirm that differences in language abilities between sexes remain into later life and are significantly larger than those in math abilities. A 2003 study by the Programme for International Student Assessment showed that among 15-year-old students in 41 different countries, boys outperformed girls in math by a statistically small margin while girls outperformed boys in reading by a larger margin. In Iceland, girls actually performed better than boys at math, and in all countries few sex differences were found in science performance.
Robert Sternberg, a professor of psychology and education, said differences between the sexes exist for specific tasks, but most research does not confirm broad generalizations about superiority in science and math. Men tend to be overrepresented at both the top and bottom of performance scales, he said.
Neurobiology professor Paul Forscher said human brain function is too complex and enigmatic to make any assumptions about cognitive sex differences. While the importance of sex differences in lower animals is more clear-cut, he said, choices are more important in explaining human behavior.
“We’re homo sapiens, we have culture, we decide what we’re going to do and we have rights,” he said. “I’ve seen so many examples of females doing as well as or better than males simply because they decided to.”
A study by professors at Stanford University and the Universities of Waterloo and Michigan has shown that women who are told they will perform poorly on a math test do not score as well as men taking the same test, but women told they have an equal chance of success will score as well as men.
The PISA study also found that while girls reported more positive attitudes towards school in general, they often had lower interest and confidence in math and science.
Mathematics major Rachel Scheinerman ’05 said the math classes she has taken since middle school have been predominantly male, and she often sees female students act less aggressively and take smaller risks in problem-solving than their male counterparts. She said she believes that despite differences in attitudes, women are equally skilled as men at problem-solving, though their success depends on equal environments and encouragement.
“This is something that Harvard and Yale have yet to achieve,” Scheinerman wrote in an e-mail. “Consider that no tenured math faculty are women.”
Neurobiology professor Amy Arnsten said she believes women are still having a hard time leading careers in science at Yale, often because of double standards within married couples. She said women are more likely to be flexible about moving to accommodate their husband’s career.
Though low numbers of tenured female faculty at Yale reflect a national trend, with women constituting only 19 percent of tenured Yale faculty in 2002, recently the numbers have been growing. The University had a record number of female tenures in 2003, with eight of its 14 appointments going to women, and two out of three professors who received approval for tenure in December 2004 were women in science departments. Astronomy professor Sarbani Basu was the first female professor to be granted tenure in her department.