He-Men in Training : Dolls or Trucks--the Play’s the Thing

Truck? Check. Helicopter? Check. Barbie doll? Uh . . . nope.

UCLA psycholo gist Melissa Hines watches 3- to 8-year-old girls and boys play with toys. The noted neuroscientist’s quest: To find out how females and males are different and why.

On the average (surprise, surprise) the boys who file into Hines’ lab prefer typically guy things, like trucks, while the girls prefer typically girl things, like dolls.

The ongoing study is part of a growing body of gender-difference research indicating that males and females do indeed differ in some areas of behavior and cognition--and that at least some of those differences may be rooted in biology.

What, if anything, do Hines’ truck-and-doll findings mean?

Part of the answer may lie in a particular group of girls in the study who, because of a genetic disorder, were exposed prenatally to high levels of androgens--the hormones, including testosterone, that influence male sexual development. The hormone disorder is corrected after birth, but even so, in the play study, the girls who have had the condition tend to gravitate toward the guy toys.

“The prenatal androgen exposure tends to be associated with choices like cars and trucks,” says Hines, whose study started in 1986. “Our question is, does this exposure to male hormones change their behavior?”

If the answer is yes, does that mean that biology begets behavior? Hines, like many of her colleagues in gender-difference research, is cautious.

“We don’t know for sure. Each person is different. I generally view it as contributing to behavior.”

As Hines describes it, there are four general hypotheses. Behavioral gender differences have to do with:

* The XY (male) versus the XX (female) chromosomes.

* Something about those hormones.

* Socialization: We tend not to reward girls for rough-and-tumble play, for example, or boys for choosing dolls.

* Cognitive development: Boys and girls learn as they grow that one set of values is so-called boy values and another, so-called girl values, and they learn to act accordingly.

Says Hines: “I would suspect that no one hypothesis holds the answer. It’s not just that simple.”