Wednesday, September 20, 2006

Sex, Science and Stereotypes

That would be a good name for a movie, starring David Brooks as the earnest and impartial neuroscientist who finds, after all, that girls are icky. Brooks has written yet another column about how the old sexual stereotypes are all validated by science:

Over the past several weeks, I've found I can change the conversation at any social gathering by mentioning Louann Brizendine's book, "The Female Brain." Brizendine is a neuropsychiatrist and the founder of the Women's and Teen Girls' Mood and Hormone Clinic in San Francisco. She's written a breezy — maybe too breezy — summary of hundreds of studies on the neurological differences between men and women.

All human beings, she writes, start out with a brain that looks female. But around the eighth week in the womb, testosterone surges through male brains, killing cells in some regions (communications) and growing cells in others (sex and aggression).

By the time they are three months old, girls are, on average, much better at making eye contact with other people and picking up information from faces. During play, girls look back at their mothers, on average, 10 to 20 times more than boys, to check for emotional signals. Girls can also, on average, hear a broader range of sounds in the human voice, and can better discern changes in tone.


This shift in how we see human behavior is bound to have huge effects. Freudianism encouraged people to think about destroying inhibitions. This new understanding both validates ancient stereotypes about the sexes, and fuzzes up moral judgments about human responsibility (biology inclines individuals toward certain virtues and vices).

Once radicals dreamed of new ways of living, but now happiness seems to consist of living in harmony with the patterns that nature and evolution laid down long, long ago.

What I got from those last two paragraphs is something very different from what Brooks probably intended. Remember how very respected the Freudian explanations of women's problems used to be (and still are in many circles)? Well, now we just have a new pseudoscience to explain away inequality. Nothing to see here, feminists. You have been beaten in your own game, probably because you hear too well.

Why, by the way, do I call this pseudoscience? Because Brooks's argument about "the patterns that nature and evolution laid down long, long ago" is an impossible one to subject to a proper scientific test, just as Freud's "penis envy" is. Proper scientific arguments must be testable.

Let's get back to some of stuff Brooks uses to bolster his own strong belief in stereotypes. First Brizendine's book. Here's Mark Liberman on some of the data Brizendine uses in her book:

It's recently fashionable for books and articles to enlist neuroscience in support of the view that men and women are essentially and unavoidably different, not just in size and shape, but also in just about every aspect of the way they see, hear, feel, talk, listen and think. These works tend to confirm our culture's current stereotypes and prejudices, and the science they cite is often overinterpreted, and sometimes seems simply to have been made up. I recently discussed an example from Leonard Sax's book Why Gender Matters ("Are men emotional children?", 6/24/2006), which David Brooks has used to support an argument for single-sex education. The latest example of this genre, released August 1, is Louann Brizendine's book "The Female Brain".

Here's what its jacket blurb says:

Every brain begins as a female brain. It only becomes male eight weeks after conception, when excess testosterone shrinks the communications center, reduces the hearing cortex, and makes the part of the brain that processes sex twice as large.
Louann Brizendine, M.D. is a pioneering neuropsychiatrist who brings together the latest findings to show how the unique structure of the female brain determines how women think, what they value, how they communicate, and who they'll love. Brizendine reveals the neurological explanations behind why
• A woman uses about 20,000 words per day while a man uses about 7,000
• A woman remembers fights that a man insists never happened
• A teen girl is so obsessed with her looks and talking on the phone
• Thoughts about sex enter a woman's brain once every couple of days but enter a man's brain about once every minute
• A woman knows what people are feeling, while a man can't spot an emotion unless somebody cries or threatens bodily harm
• A woman over 50 is more likely to initiate divorce than a man
Women will come away from this book knowing that they have a lean, mean communicating machine. Men will develop a serious case of brain envy.

I looked through the book to try to find the research behind the 20,000-vs.-7,000-words-per-day claim, and I looked on the web as well, but I haven't been able to find it yet. Brizendine also claims that women speak twice as fast as men (250 words per minute vs. 125 words per minute). These are striking assertions from an eminent scientist, with big quantitative differences confirming the standard stereotype about those gabby women and us laconic guys. The only trouble is, I'm pretty sure that both claims are false.

With respect to the speech rate claim, I've just run a script on a corpus of 5,202 transcribed and time-aligned telephone conversations, involving native speakers of American English with a wide variety of ages, regions and backgrounds. The average speech rate for the males was 174.3 wpm, and the average speech rate for the females 172.6 wpm. I assume that Brizendine didn't just concoct her figures about male vs. female speech rates out of thin air -- she must have gotten them from a study that someone did somewhere, sometime, or at least from some other author plugging another work in the flourishing genre of pop gender studies -- but let's say, at least, that it ain't necessarily so. I'll post something more about Brizendine's striking speaking-rate and words-per-day claims as soon as I can figure out what evidence she based them on. [More on female and male speaking rates is here, and more on the number of words men and women typically speak per day is here.]

And what about the sensitive hearing of girls when compared to boys, the thing which makes boys unable to hear what their parents are telling them? Liberman again:

Let's zero in on the business about differences in hearing sensitivity. In her book, Brizendine puts it like this (p. 17): "Just as bats can hear sounds that even cats and dogs cannot, girls can hear a broader range of sound frequency and tones in the human voice than can boys." If we take this literally, it's nonsense. In the first place, it's simply false that girls' frequency range compares to boys' like bats to dogs, and as far as I can tell, none of the sources that she cites even suggest anything of the kind. In the second place, all the communicatively-relevant information in speech is well within the frequency range even of normal adults, who have started to lose high-frequency hearing compared to children of both sexes. But let's give Brizendine the benefit of the doubt, and interpret her as talking about a sex difference in auditory sensitivity across the shared frequency range of normal hearing.

This sex difference really exists. It's been known for half a century that girls and women have more sensitive hearing, on average, than boys and men. But those two little words "on average" are crucial. If you pick a man and a women (or a boy and a girl) at random, the chances are about 6 in 10 that the girl's hearing will be more sensitive -- but about 4 in 10 that the boy's hearing will be more sensitive. Not only that, but the expected value of the sensitivity difference is extremely small: at 1,000 Hz, our randomly-selected girl's threshold will be about 1.1 DB lower than our randomly-selected boy's threshold; at 1,500 Hz, the difference will be about 2 DB. By comparison the JND ("just noticeable difference") for soft sounds is about 1 DB.

It's a political game, my friends, the one that Brooks is playing. The idea is to take sex differences, either real or hypothesized, and then to argue that they are humongous:

Brizendine then describes waves of hormonal activity as women age. Female brains vary with the seasons of life much more than male brains. During menopause, for example, estrogen levels drop. Personalities can change as some women derive less pleasure from nurturing and more from independence. Women initiate 65 percent of divorces after age 50.

These sorts of stark sex differences were once highly controversial, and not fit for polite conversation. And some feminists still argue that talking about biological differences between the sexes is akin to talking about biological differences between the races. But Brizendine's feminist bona fides are unquestionable. And in my mostly liberal urban circle — and among this book's reviewers — almost everybody takes big biological differences as a matter of course.

Estrogen levels fall after menopause!! Who knew? All feminists are flabbergasted. And how is the possible fact (I haven't checked it) that women initiate more divorce after the age fifty a clear proof of something biological? How are these sex differences "stark"? How are these biological differences "big"? What about all the studies which demonstrate the much greater similarity between the sexes in most forms of cognition?

It really is high time to start discussing the way science is popularized these days, especially the hidden political motives underlying it. A very good starting point might be this:

In my opinion, the most important insight in this area right now is Deena Skolnick's demonstration of the power of neuroscience to cloud people's minds. She took explanations of psychological phenomena that had been crafted to be "awful", and which (in their plain form) were recognized as bad both by novices and by experts, and added some (totally irrelevant) sentences about brain anatomy and physiology. With the added neuroscientific distraction, the bad explanations were perceived as satisfactory ones. [The paper with the details of this research has not yet been published -- I promise to discuss it in more detail once the details are generally available. The mass media certainly offer plenty of anecdotal evidence these days for Skolnick's idea.]

Yes, there is this respect for science we all seem to have. It most likely has something to do with the adulation of Einstein's theory of relativity and the invention of antibiotics and other great scientific findings of the past. But we have to learn to understand that just because something is framed in science-babble it's not necessarily true. We have to learn that science writers may not be neutral. And we really have to learn the difference between a characteristic having slightly varying average values for men and women, with large overlaps in the distributions, and the idea that women are from Venus and men from Mars.