So you thought you understood teens

We're tuned in, we Facebook, and 40 is the new 30.

We understand what's going through the minds of those in the younger generations.

Except we don't, according to two new studies that suggest we adults need to challenge our assumptions about how young people look at the world.

One, published this week in the journal Pediatrics, presents evidence overturning the standard belief that teens do risky things because they feel invulnerable.

Instead, the study suggests teens who get involved in dangerous behavior are likely to do it because they believe they're going to die young anyway.

Rather than "it can't happen to me," the thinking is more like "it will happen to me, so why be careful?"

Fifteen percent of the 20,594 teens surveyed felt the odds were less than 50/50 that they'd live to age 35, with an even higher rate among low-income, black and Native American youths.

It's a crucial difference that colors how we approach efforts to keep teens from driving drunk, using drugs, getting in fights, engaging in risky sexual behavior, or attempting suicide, says Dr. Benjamin Shain, a child and adolescent psychiatrist in Highland Park and liaison to the American Academy of Pediatrics Committee on Adolescence.

To use just one example, it's the difference between "scared straight"-style interventions that show students how they could die and other programs designed to give teens hope, said Shain, who was not involved in the study. For instance, at-risk teens could be shown stories of others who once felt similarly fatalistic but went on to lead full, happy lives, Shain said.

The research points to one simple tool: asking teens to assess their likelihood of living into middle age can help identify those who are involved in risky behavior or who are likely to be in the future.

And that feeling of invincibility, long attributed to teens? It's actually far more common in adults, according to earlier research cited in the new report.

It's not so surprising that we've gotten it wrong, if you believe another new study.

This one, a survey by the Pew Research Center, concludes that the generation gap is wider now than it has been at any time since the culturally cataclysmic 1960s. And it's not just your iPod playlist that divides the age groups - it's social values and morality, 47 percent of those surveyed said.

Combined, these two studies point to an urgent need to find new ways to relate to one another across the generations, to open our minds and to reassess what we do to keep our youth away from dangerous behavior.