Thursday, August 10, 2017

Meanwhile, down on the Farm

The Spring 2017 issue of the Stanford Medical School magazine has a special theme: Sex, Gender, and Medicine. I recommend the article excerpted below to journalists covering the Google Manifesto / James Damore firing. After reading it, they can decide for themselves whether his memo is based on established neuroscience or bro-pseudoscience.

Perhaps top Google executives will want to head down the road to Stanford for a refresher course in reality.

Stanford Neuroscience Professor Nirao Shah and Diane Halpern, past president of the American Psychological Association, would both make excellent expert witnesses in the Trial of the Century.
Two minds: The cognitive differences between men and women

... Nirao Shah decided in 1998 to study sex-based differences in the brain ... “I wanted to find and explore neural circuits that regulate specific behaviors,” says Shah, then a newly minted Caltech PhD who was beginning a postdoctoral fellowship at Columbia. So, he zeroed in on sex-associated behavioral differences in mating, parenting and aggression.

“These behaviors are essential for survival and propagation,” says Shah, MD, PhD, now a Stanford professor of psychiatry and behavioral sciences and of neurobiology. “They’re innate rather than learned — at least in animals — so the circuitry involved ought to be developmentally hard-wired into the brain. These circuits should differ depending on which sex you’re looking at.”

His plan was to learn what he could about the activity of genes tied to behaviors that differ between the sexes, then use that knowledge to help identify the neuronal circuits — clusters of nerve cells in close communication with one another — underlying those behaviors.

At the time, this was not a universally popular idea. The neuroscience community had largely considered any observed sex-associated differences in cognition and behavior in humans to be due to the effects of cultural influences. Animal researchers, for their part, seldom even bothered to use female rodents in their experiments, figuring that the cyclical variations in their reproductive hormones would introduce confounding variability into the search for fundamental neurological insights.

But over the past 15 years or so, there’s been a sea change as new technologies have generated a growing pile of evidence that there are inherent differences in how men’s and women’s brains are wired and how they work.

... There was too much data pointing to the biological basis of sex-based cognitive differences to ignore, Halpern says. For one thing, the animal-research findings resonated with sex-based differences ascribed to people. These findings continue to accrue. In a study of 34 rhesus monkeys, for example, males strongly preferred toys with wheels over plush toys, whereas females found plush toys likable. It would be tough to argue that the monkeys’ parents bought them sex-typed toys or that simian society encourages its male offspring to play more with trucks. A much more recent study established that boys and girls 9 to 17 months old — an age when children show few if any signs of recognizing either their own or other children’s sex — nonetheless show marked differences in their preference for stereotypically male versus stereotypically female toys.

Halpern and others have cataloged plenty of human behavioral differences. “These findings have all been replicated,” she says.

... “You see sex differences in spatial-visualization ability in 2- and 3-month-old infants,” Halpern says. Infant girls respond more readily to faces and begin talking earlier. Boys react earlier in infancy to experimentally induced perceptual discrepancies in their visual environment. In adulthood, women remain more oriented to faces, men to things.

All these measured differences are averages derived from pooling widely varying individual results. While statistically significant, the differences tend not to be gigantic. They are most noticeable at the extremes of a bell curve, rather than in the middle, where most people cluster. ...

See also Gender differences in preferences, choices, and outcomes: SMPY longitudinal study. These preference asymmetries are not necessarily determined by biology. They could be entirely due to societal influences. But nevertheless, they characterize the pool of human capital from which Google is trying to hire.
The recent SMPY paper below describes a group of mathematically gifted (top 1% ability) individuals who have been followed for 40 years. This is precisely the pool from which one would hope to draw STEM and technological leadership talent. There are 1037 men and 613 women in the study.

The figures show significant gender differences in life and career preferences, which affect choices and outcomes even after ability is controlled for. (Click for larger versions.) According to the results, SMPY men are more concerned with money, prestige, success, creating or inventing something with impact, etc. SMPY women prefer time and work flexibility, want to give back to the community, and are less comfortable advocating unpopular ideas. Some of these asymmetries are at the 0.5 SD level or greater. Here are three survey items with a ~ 0.4 SD or more asymmetry:

# Society should invest in my ideas because they are more important than those of other people.

# Discomforting others does not deter me from stating the facts.

# Receiving criticism from others does not inhibit me from expressing my thoughts.

I would guess that Silicon Valley entrepreneurs and leading technologists are typically about +2 SD on each of these items! One can directly estimate M/F ratios from these parameters ...
For example, if a typical male SV entrepreneur / tech leader is roughly +2SD on these traits whereas a female is +2.5SD, the population fraction would be 3:1 or 4:1 larger for males. This doesn't mean that the females who are > +2.5SD (in the female population) are ill-suited to the role (they may be as good as the men), just that there are fewer of them in the general population. I was shocked to see that even top Google leadership didn't understand this point that Damore tried to make in his memo.

A 6ft3 Asian-American guard (Jeremy Lin) might be just as good as other guards in the NBA, but the fraction of Asian-American males who are 6ft3 is smaller than for other groups, like African-Americans. Even if there were no discrimination against Asian players, you'd expect to see fewer (relative to base population) in the NBA due to the average height difference.

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