August 19, 2007

And why "without sauce"?

Because I've posted from time to time on the neuroscience of sex differences, several readers have sent me links to this passage from Barbara Ehrenreich's 8/2/2007 blog post "Opportunities in Abstinence Training":

Most people, though, require a bit of training to get into the abstinence training business, so I went to the website of WAIT Training to look at the sample curriculum for an abstinence course. The suggested syllabus contained a lot about love, marriage and STD’s—none of it terribly technical – until I got to the part about how to explain the difference between the sexes, where the following demonstration was suggested:

Bring to class frozen waffles and a bowl of spaghetti noodles without sauce. Using these as visual aides, explain how research has found that men’s brains are more like the waffle, in that their design allows them to more easily compartmentalize information. Women’s minds, on the other hand are more interrelated due to increased brain connectors.

Maybe my spaghetti brain wasn’t up to this challenge, but it did seem to imply that sex would involve a mixing of waffles and pasta, possibly with maple syrup for lubrication. Disgusting, yes, but no doubt a surefire recipe for abstinence.

The WAIT training manual in question is here, and the waffles-v.-spaghetti passage is on page 197, under the heading "Make an impact".

The manual gives as a source “Man’s World, Women’s World? Brain Studies Point to Differences” by Gina Kolata, New York Times, Feb. 28, 1995. There was nothing in Kolata's story about waffles or spaghetti, with or without syrup and sauce. And there was nothing in it about effect sizes, either, though there was a flurry of caveats from quoted scientists, like Sally Shaywitz's "We have to be very, very careful". The WAITers seem to understand that concept better with respect to adolescent sexuality than with respect to neuroscience.

Kolata's article does cite some not-so-careful assertions that have since been refuted, for example:

Several years ago, Dr. Witelson reported that women have a larger corpus callosum, the tangle of fibers that run down the center of the brain and enable the two hemispheres to communicate.

Two years later, in 1997, there was a pretty definitive refutation of that idea by K.M. Bishop and D. Wahlsten, "Sex Differences in the Human Corpus Callosum: Myth or Reality?", Neuroscience & Biobehavioral Reviews, 21(5) 581-601, 1997:

It has been claimed that the human corpus callosum shows sex differences, and in particular that the splenium (the posterior portion) is larger in women than in men. Data collected before 1910 from cadavers indicate that, on average, males have larger brains than females and that the average size of their corpus callosum is larger. A meta-analysis of 49 studies published since 1980 reveals no significant sex difference in the size or shape of the splenium of the corpus callosum, whether or not an appropriate adjustment is made for brain size using analysis of covariance or linear regression. It is argued that a simple ratio of corpus callosum size to whole brain size is not an appropriate way to analyse the data and can create a false impression of a sex difference in the corpus callosum. The recent studies, most of which used magnetic resonance imaging (MRI), confirm the earlier findings of larger average brain size and overall corpus callosum size for males. The widespread belief that women have a larger splenium than men and consequently think differently is untenable. Causes of and means to avoid such a false impression in future research are discussed.

There are some differences in the average characteristics of male vs. female brain anatomy and physiology, but all of them involve highly overlapped distributions and small effect sizes. It's not like frozen waffles vs. sauceless spaghetti -- it's more like Eggo vs. Pillsbury frozen waffles, or Barilla vs. Buitoni spaghetti.

If a WAIT trainer compared a bowl of Barilla spaghetti to a bowl of Buitoni spaghetti in order to demonstrate the difference between male and female brains, this would make a more scientifically valid impact. Here's a suggestion for an even more impactful exercise -- combine a handful of each type out of the box, cook them together, drain, serve -- and ask the class to sort the strands by brand.

Posted by Mark Liberman at August 19, 2007 06:25 PM