JIM LEHRER: Now: What happens to teenage brains in a multitasking, digital age?
NewsHour science correspondent Miles O'Brien has our look.
MILES O'BRIEN: It's a school night, and the 16-year-old Jain twins, Rakhee and Anika, have a heavy load of homework ahead of them. So, where to begin? How 20th century of me to think that way. The correct answer is: Do everything all at once.
ANIKA JAIN, 16 Years Old: Well, right now, I am working on my physics lab and my "Hamlet" essay. I am also on Gmail doing chat and on Facebook chat.
MILES O'BRIEN: Actually, everything and then some.
RAKHEE JAIN, 16 Years Old: Well, I am doing my math homework. I am editing an article for the newspaper. And then I will worry about the other stuff later.
MILES O'BRIEN: So, you have got the Facebook, a couple of -- you have some chats going?
RAKHEE JAIN: Yes.
MILES O'BRIEN: Yes. And then you have got three type -- three kinds of homework that you are working on at the same time?
RAKHEE JAIN: Kind of, yes.
MILES O'BRIEN: The Jains are like most kids these days. It is second nature for them to be online, on the air, typing, texting, posting, perusing, constantly connected. Well-informed? Yes, but perpetually tempted and, well, to my eyes, distracted.
It's kind of addictive.
ANIKA JAIN: It is, yes. Like, I know it's bad. I know I shouldn't be chatting with people, because it's -- it's -- it's there. You've got to utilize your resources.
MILES O'BRIEN: And all of this is likely affecting the Jains' brains at a crucial phase in their development, but how?
Neuroscientist Jay Giedd hopes to have an answer before too long.
DR. JAY GIEDD, neuroscientist, National Institute of Mental Health: The Internet and iPods and Facebook and all of these video games, and these changes are so recent in terms of human history, that it is going to be very interesting to see how the brain adapts to doing all these different things, and often many of them at the same time.
MILES O'BRIEN: The Jains are part of a 20-year study Dr. Giedd is conducting at the National Institute of Mental Health to better understand how the adolescent brain develops. All the participants come in every two years for a gauntlet of tests, including some time in a magnetic resonance imaging machine, which captures the development of their brains in vivid detail.
DR. JAY GIEDD: So, we were quite surprised to find that, by age 6, the brain is already over 90 percent of adult size. So, the size of the brain gets set surprisingly young. But what happens after that is, the brain becomes more specialized. And it does this through a process called pruning -- it's kind of a gardening metaphor -- of eliminating extra connections.
MILES O'BRIEN: The prime time for pruning is adolescence. Connections that are used are strengthened. Those that aren't are disconnected. This is the time when human beings learn to live independently in their environment -- 10,000 years ago, teens would have been learning how to stay warm, what berries to eat, or how to hunt.
Today, they are learning how to drink from a technological fire hose.
DR. JAY GIEDD: And, in fact, in their adult jobs, they may be doing a lot of multitasking. But the other side of that coin is, will they become less good at focusing on one task, of being able to do one thing really well?
MILES O'BRIEN: This is something I think a lot about, when I am not distracted by my own multitasking. Why? Well, because of these tech-savvy characters with voracious appetites for the online smorgasbord. That's my 18-year-old son, Murrough...
MURROUGH O'BRIEN, 18 Years Old: Oh, suck it. You, dude, I have 16 kills.
MILES O'BRIEN: ... answering the call of duty with his pal Dylan (ph).
DYLAN: Murrough wins.
MILES O'BRIEN: On the other side of the apartment is 16-year-old Connery, who presides over a nonstop virtual salon. She and her coterie connect via text, instant messages, Facebook, and video chats.
Are you doing homework, Connery?
CONNERY O'BRIEN, 16 Years Old: No, no.
MILES O'BRIEN: Not even close?
CONNERY O'BRIEN: No.
MILES O'BRIEN: What are you doing?
CONNERY O'BRIEN: I am looking at funny pictures on Facebook.
MILES O'BRIEN: Watch what happens when I try to interview her.
Here's the big question, though. Do you think that -- of course, with iChat, it kind of helps. But, like, for example, like, what were you just doing? What were you just doing?
CONNERY O'BRIEN: I was just checking my texts.
MILES O'BRIEN: Just checking -- what were you checking?
CONNERY O'BRIEN: I was checking my texts and the time.
MILES O'BRIEN: You just couldn't even -- you couldn't even do the interview without doing a quick check, right, you know?
CONNERY O'BRIEN: Sorry, it was just a reflex.
MILES O'BRIEN: That's an addiction.
What have we wrought? Well, try this term on for size: digital natives.
DR. GARY SMALL, UCLA: Digital natives are essentially young people who grow up with the technology 24/7. Their brains are wired to use it well, use it effectively.
MILES O'BRIEN: Gary Small is a psychiatry professor at UCLA and co-author of "iBrain: Surviving the Technological Alteration of the Modern Mind."
He says we are creating a generation of technology addicts, for real. You see, every time we do something new and fun, our brain rewards us with a jolt of a chemical called dopamine. It's the drug our body secretes when we do something pleasurable and/or addictive.
DR. GARY SMALL: What the technology really does, it accelerates anything that is human, anything that we like. We can get addicted to being connected with other people through texting, through social networking, all kinds of programs that are very seductive to our brains.
MILES O'BRIEN: It is seductive, no matter what the age, but is it efficient? Can we really multitask?
Well, yes, with a caveat.
MARCEL JUST, Carnegie Mellon University: We can do it, but at tremendous cost. You can't do two tasks as well as you can do each one separately.
MILES O'BRIEN: Neuroscientist Marcel Just is doing some groundbreaking research on the human brain at Carnegie Mellon University.
So, we pay a big penalty for doing more, two things at once?
MARCEL JUST: That's right. There's only so much brain capability at any one time, throughput. And you can divide it down as much as you want to, but the price will be even higher then.
MILES O'BRIEN: Like driving and talking on the phone. A few years ago, Just did a study on this. His conclusion? Even an idle conversation takes a 40 percent bite out of your brainpower. You might as well be drunk.
So, multitasking is not a myth, but efficient multitasking might be?
MARCEL JUST: Yes. Multitasking with no cost is a myth. I think there's no free lunch there.
MILES O'BRIEN: Oh, boy. A little nervous.
But some people are better multitaskers than others, and it is harder for us non-digital natives, which is what brought me to Carnegie Mellon for a multitasking challenge.
With headphones on, I tried to correctly answer a series of simultaneous questions like these.
MILES O'BRIEN: There was a lot on the line here. I consider myself a good multitasker. You really should be if you are going to fly airplanes, as I do. So, if I flunked this test, I would never hear the end of it. But only 40 percent of the students in the initial study passed.
MAN: So, 100 on left and right and a 93 on dual.
MILES O'BRIEN: Ninety-three on dual?
MAN: So, you got it.
MILES O'BRIEN: Whew. Enough to save multitasking face and get me into the functional MRI, which images blood flow in the brain to show which areas are in use.
And here are the results. This is my brain listening to just one question, and here I am trying to answer two at once. It ties up a lot more gray matter, and that matters a lot.
MARCEL JUST: Thinking is a network function. Now, if you ask your brain to do two thinking tasks simultaneously, the two networks have to work at the same time. They have to communicate over the same channels.
MILES O'BRIEN: So, can we train our brains to do better?
Daphne Bavelier thinks so. She is a professor in the Brain and Cognitive Sciences Department at the University of Rochester. She has done a lot of research on video game players. And parents, the news is a little bit counterintuitive.
DAPHNE BAVELIER, professor, Brain and Cognitive Sciences Department at the University of Rochester: We can show that they have better vision, the kind of skills that are not typically corrected by training, but corrected by your glasses, which is not something that you would think playing video games actually changes.
And it's not only the case for vision, but it's also the case for attention, for different aspects of cognition, like multitasking, visual short-term memory.
MILES O'BRIEN: And Bavelier says the games that are most beneficial are most beneficial are not the ones you might suspect.
No disagreement from the "Halo" legend known as Flamesword, AKA Michael Chaves. He's a professional video gamer. Yes, kids, you can get paid to do this. even though I hesitate to mention it.
MICHAEL CHAVES, "Flamesword": I think I think faster. I have more outcomes in my head. I'm always thinking, because, in the game, you are trying to accomplish certain tasks, and there's many different ways to accomplish these tasks. And if I could do it in the game, I feel I do it in person, too. And I am just always thinking of different ideas.
MILES O'BRIEN: So, is it possible we are collectively building better brains? Probably. They almost certainly are different.
MURROUGH O'BRIEN: And we are dependent on technology. Let's be honest here. And, yes, so, it's definitely going to wire my brain differently than it -- than how your brain was wired growing up.
MILES O'BRIEN: What is your generation going to be like as adults? Should we be worried about you running the world? I mean...
ANIKA JAIN: Don't be worried. We got this.
RAKHEE JAIN: Ah, yes.
MILES O'BRIEN: I suppose cavemen parents worried about their kids playing with that newfangled fire.