The Women's Sports Foundation found that 6 girls drop out of sports for every 1 boy by the end of high school, and a recent Girl Scout study found that 23 percent of girls between the ages of 11 and 17 do not play sports because they do not think their bodies look good doing so.
And looking good, Ms. Lamb says, is increasingly tied to what it means to play. Star female athletes regularly pose naked or seminaked for men's magazines; girls see cheerleaders (with increasingly sexualized routines) on TV far more than they see female basketball players or other athletes.
The effects are felt in academia as well. Earlier this year, a Princeton University study found a growing leadership gap among male and female undergraduates. Nannerl Keohane, who chaired the Princeton steering committee, wrote in an e-mail interview that "the climate was different in the late 1990s and the past decade." And she linked the findings to shifts in popular culture such as "the receding of second-wave feminist excitement and commitment, a backlash in some quarters, a re-orientation of young women's expectations based on what they had seen of their mothers' generation, a profound reorientation of popular culture which now glorifies sexy babes consistently, rather than sometimes showing an accomplished woman without foregrounding her sexuality."
This "sexy babes" trend is a big one.
"For young women, what has replaced the feminine mystique is the hottie mystique," Ms. Coontz says. "Girls no longer feel that there is anything they must not do or cannot do because they're female, but they hold increasingly strong beliefs that if you are going to attempt these other things, you need to look and be sexually hot."
In television shows, for instance, women are represented in far more diverse roles – they are lawyers, doctors, politicians. But they are always sexy. A woman might run for high political office, but there is almost always analysis about whether she is sexy, too.