Tuesday, May 10, 2011

Ladies, Be Prepared To Cry. For Today's Fun Research Popularization Is Out.

Today's fun research popularization. It's breezy, it's flippant, and it's on gender differences in compassion:
Nearly everyone agrees that women, on the whole, are more compassionate than men. In a 2008 Pew research poll, 80 percent of Americans expressed that view.
Is this a sexist stereotype? Apparently not. Newly published brain-imaging research suggests that, in this case, conventional wisdom is correct.
It finds women’s brains process compassion differently than men’s, apparently due to the distinctive way our respective neural systems evolved.
Mmm. Strong stuff! We start with a stereotype. Then we argue that science has proved it correct. Then we argue that the reason is in the evolution of our neural systems! And note that a study which actually does not find a difference in reported compassion but in brain activity by gender is used to defend a stereotype that such a difference exists.

I love this stuff. What comes next? We are told that the study had TWELVE men and TWELVE women look at 100 pictures, fifty of which depicted scenes that were expected to provoke compassion. The brains of those 24 participants were scanned with fMRI technology.

The findings? Sure, men and women were equally likely to REPORT the same number of compassionate experiences, but see what happens when we peek inside their brainz:

However, what was happening in the participants’ brain told a different story. As the compassion-evoking photos were viewed, activity was observed in two areas of the brain — the thalamus and the putamen, part of the basal ganglia — in women but not in men.

“Also, women showed a greater activation in the cerebellum, a structure governing fine movement control that is also involved in judgment, selective attention and affective experiences,” they report. “The cerebellum may play a role in the decision to execute helping actions.”
From all this the researchers concluded, as clearly is completely appropriate, that:
“Our results suggest that compassion mechanisms evolved differentially in women, probably in connection with social skills including maternal preverbal communication and emotional responses to helpless offspring,” a research team led by Roberto Mercadillo of the National Autonomous University of Mexico’s Institute of Neurobiology writes in the journal Brain and Cognition.
I should look up the actual results, sigh, because statements like "activity was observed in two areas of the brain — the thalamus and the putamen, part of the basal ganglia — in women but not in men" may mean lots of different things in terms of numbers in those two study samples. Did all women have the same reaction, for instance? Any outliers among the twelve men or the twelve women? Outliers have a very big effect in small studies.

Then there is the fact that brain activity may change based on the way brains are used. And the difficulty in interpreting some of these types of scans. And the obvious fact that observing such differences, even if the study was done perfectly, tells us nothing about the evolution of compassion mechanisms.

But none of this matter anywhere near as much as something I wrote about a few months ago:
In 1995 a wife-husband research team published the first study appearing to show that men and women process language differently in their brains. Sally and Bennett Shaywitz used functional MRI to study the brains of nineteen women and nineteen men during three different language tasks.

One of the tasks, identifying rhymes, showed gender differences in the relative activation levels of the brain. Lise Eliot in Pink Brain. Blue Brain. writes (pp. 185-6):

...men exhibited strong activation of the lower portion of the left frontal lobe, while women tended to activate the same frontal area but on both sides of the brain. Of the nineteen women, eleven exhibited this bilateral pattern and eight activated just the left hemisphere (like men). So the results of this study seemed to indicate that in processing language, or at least during this particular rhyming task, women were more likely to use both hemispheres while men used exclusively the left hemisphere. As one of the first reports to find a sex difference by using functional MRI, this study got a lot of press. An article in the New York Times Science section promptly declared: "Men and Women Use Brain Differently, Study Discovers," and the findings continue to be highlighted even in recent popular works.


later studies failed to replicate Shaywitzes' original finding. Eliot again (pp. 186-7):

Like any good research, the Shaywitzes' study inspired many attempts at replication. By 2008, twenty-six comparable brain-imaging studies were available for Iris Sommer and her colleagues at the University of Utrecht in the Netherlands to synthesize using meta-analysis.

Their overall conclusion: there's no sex difference in language processing. While some studies reported results similar to the Shaywitzes', others did not. Some even found that women processed language more strongly on the left side. When you put all the findings together, it's a wash; there is no significant difference in the way men's and women's right and left hemispheres are activated by language.

All this has to do with the idea that brain lateralization might differ between men and women in language use. This doesn't seem to be the case. But no worries! We still get a lot of popularizations based on exactly that idea, even though it has now been removed from the relevant university-level textbooks.

The short message: Wait to see if a small study indeed is replicated by others before popularizing a message that women are more compassionate than men based on evolutionary reasons.

But here is the weirdest thing about this particular popularization: Its use:
So ladies: When the men in your life seem insensitive to suffering, try not to respond with scorn. The problem, it seems, is one of brain circuitry. It shouldn’t be hard to take pity on them; after all, you have an enormous capacity for compassion.
See how we have completely forgotten that the men and women in the study reported the same number of compassionate episodes?! It's the brain scans which determine the extent of our compassion now.

Now that was fun.