The research that goes into children's television is also astonishing. One show my kids love is Blues Clues. The success of this show was not accidental. The producers did a tremendous amount of research into the cognitive abilities and attention span of three and four years olds to craft every show.
I don't know if as much research goes into children's literature. In general, I think the younger the children, the more research there is on how to package uplifting and educational messages for the target age group. Of course, this is because the younger the children, the more the target (buying) audience is actually the parents. Parents want the literary equivalent of health food for their kids.
By the time the readers reach their teens -- Middle Grade and Young Adult -- the buyers are frequently the teens themselves. Even if the credit card is still mom's or dad's. But parents, teachers and other adults still buy books, and they still do it with the hope of moulding (or at least not corrupting) pliable minds. Notice that the article complaining about the darkness in YA was a mom trying to purchase books for her daughter.
There was an interesting study of Romance heroes done by Daniel J. Kruger, Maryanne Fisher and Ian Jobling, which compared reader's preferences for certain kind of romantic heroes. The heroes were coded according to whether they were dark and dangerous (anti-heros) or noble and chivalrous (traditional heroes). Female readers were't told that the descriptions of the men were from fiction, and were asked various questions hinged on imagining themselves in relationships with these men. Most women preferred the anti-hero for a one night stand, but the chivalrous hero for a long term relationship.
However, even the women who were intrigued by the idea of a fling with the anti-heros overwhelmingly agreed on one thing: when it came to choosing between these two men for their daughters, they almost all wanted the chivalrous man for their daughters.
It is striking that 60 percent of women would prefer to have sex with [the anti-hero], a cad, but only 13 percent would prefer to see him engaged to their twenty-five-year-old-daughter....You might think this was a generational thing, that of course old fuddy-duddy moms of an older generation would be more conservative, but in fact the participants of the study, as in most human-rat-maze experiments, were college students.
The women in this study were similar in age to their imagined twenty-five daughter, and yet they were able to state a preference that would be appropriate for a potential grandmother.By the way, this shows that it's not a matter of age, so much as relationship. It's not that adults consider teens as other. It's that people, as parents or even when they just imagine being parents, look something different in literature for their children than for themselves.
Generations of researchers have debated whether violence in video games and on television causes a rise in criminal violence in society. Fretting over violence or "darkness" in literature has not been nearly as fevered. (Before TV, concern over literature occupied a greater fraction of the global reserve of Worry That Young Minds Are Going To The Dogs.)
These questions are not quite the same as asking what kind of literature is "best suited" to teens. The problem is that it is difficult to untangle what we mean by "best." Is "best" mean most entertaining, best selling, most educational, most conducive to being a whole, rounded, compassionate and intelligent person? And how would we measure that? We can ask children to sing their ABCs or share toys, but its harder to evacuate the intellectual and emotional growth of teens and adults.
So Young Adult books are judged as effective by the de facto method our society uses for judging the success of most things: number of sales and final dollars earned.