And by age 20, their brains respond to this task much as the adults' do.Luna suspects the improvement comes as richer networks and faster connections make the executive region more effective.This synaptic pruning, as it is called, causes the brain's cortex—the outer layer of gray matter where we do much of our conscious and complicated thinking—to become thinner but more efficient.Taken together, these changes make the entire brain a much faster and more sophisticated organ.It was the brain scans she took while people took the test.Compared with adults, teens tended to make less use of brain regions that monitor performance, spot errors, plan, and stay focused—areas the adults seemed to bring online automatically.
Over the past five years or so, even as the work-in-progress story spread into our culture, the discipline of adolescent brain studies learned to do some more-complex thinking of its own.
To succeed, you must override both a normal impulse to attend to new information and curiosity about something forbidden. Ten-year-olds stink at it, failing about 45 percent of the time. In fact, by age 15 they can score as well as adults if they're motivated, resisting temptation about 70 to 80 percent of the time.
What Luna found most interesting, however, was not those scores.
This revelation suggested both a simplistic, unflattering explanation for teens' maddening behavior—and a more complex, affirmative explanation as well.
The first full series of scans of the developing adolescent brain—a National Institutes of Health (NIH) project that studied over a hundred young people as they grew up during the 1990s—showed that our brains undergo a massive reorganization between our 12th and 25th years.
"Well," I huffed, sensing an opportunity to finally yell at him, "what would you call it? " 'Reckless' sounds like you're not paying attention. I made a deliberate point of doing this on an empty stretch of dry interstate, in broad daylight, with good sight lines and no traffic. —and revealed an answer that surprised almost everyone.