'Internal Chatter' Limits Multitasking As People Age Research shows that the human brain reaches its multitasking peak in our 20s or 30s. As we age beyond that, an increase in "internal chatter" makes the brain work harder to suppress distractions and maintain focus.
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'Internal Chatter' Limits Multitasking As People Age

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'Internal Chatter' Limits Multitasking As People Age

'Internal Chatter' Limits Multitasking As People Age

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STEVE INSKEEP, host:

It's Morning Edition from NPR News. I'm Steve Inskeep.

RENEE MONTAGNE, host:

And I'm Renee Montagne. It's not every brain scientist who explains her research using Shakespeare.

Professor CINDY LUSTIG (Psychology, University of Michigan): One man in his time plays many parts, his acts being seven ages. At first the infant, muling and puking in the nurse's arms, and then the whining schoolboy with his...

MONTAGNE: The person reciting those famous words is Cindy Lustig who uses them to explain something that Shakespeare never heard of: multitasking. The ability to do several things at once changes over a lifetime. We develop it late in childhood, then begin to lose it as we age. The many ages of man and multitasking. That's the subject for the final story in our series on how we manage many things at once, as NPR's Jon Hamilton reports.

JON HAMILTON: Shakespeare casts both the very young and the very old as pretty limited mentally. So when I sit down with Cindy Lustig in her lab at the University of Michigan, I have a question. Did Shakespeare have it right?

Professor LUSTIG: Well, he had a right in terms of the behavior.

HAMILTON: At least when it comes to multitasking. Lustig says children have trouble doing it. So do people in their 60s and beyond.

Professor LUSTIG: You know, everybody is always looking back fondly upon their 20s and 30s and so on, and you know, we do seem to reach some kind of a peak there.

HAMILTON: Studies show that young adults can do several things at once faster and more accurately than people who are either older or younger.

Unidentified Child: I say, twinkle, twinkle, little star. How I wonder what you are.

HAMILTON: Lustig says the problem for toddlers and preschoolers is that their brains tend to zero in on just one thing at a time.

Professor LUSTIG: So if you've ever seen a kid, you know, focusing on a game or focusing on a puzzle, they are focused on it. They are not thinking about their day. They are not thinking about a grocery list. They are not thinking about anything else. They're focused on that.

Unidentified Child: I found it.

HAMILTON: And when they do switch to something new, they tend to forget whatever it was they were doing before.

Unidentified Child: What's this?

HAMILTON: Parents exploit this.

Unidentified Child: So...

HAMILTON: When a toddler heads for big brother's favorite truck, they redirect his attention to a racecar in the corner.

Unidentified Child: Take it, I see.

HAMILTON: That can work for a two-year-old, but things change by the time children reach the age of Shakespeare's reluctant schoolboy.

Mr. LAWRENCE ROLLIE(ph): Well, I really like drawing. I drew a lot so...

HAMILTON: Lawrence Rollie is nine and likes to draw and do math.

Mr. ROLLIE: Oh, and basketball. I have a basketball hoop at home, so I practice a lot.

HAMILTON: Lawrence was in the lab to take some tests that measure how well he multitasks. He also has begun to multitask a bit while doing his homework.

Mr. ROLLIE: You have to spell words and read little stories and write summaries and things like that.

HAMILTON: And so when you were doing that, what kind of other stuff were you doing?

Mr. ROLLIE: Just watching TV usually.

HAMILTON: Is that OK with your mom?

Mr. ROLLIE: Kind of.

HAMILTON: Lawrence can do homework and watch TV at the same time because his brain has developed a lot since he was a toddler. Researcher Cindy Lustig has been scanning the brains of people of different ages to figure out how changes in certain areas affect our ability to multitask.

Professor LUSTIG: What we have here is pictures of the brain sort of sliced like a salami.

HAMILTON: She calls up the scan of a young person's brain on her computer and points to one of the critical areas.

Professor LUSTIG: You're seeing the frontal cortex. And this is the part of the brain that we think is involved in keeping you focused on the task, keeping the task in mind. So this is the thing that I'm supposed to do.

HAMILTON: The frontal cortex found just behind your forehead acts as the brain's chief executive. But it isn't fully developed in someone Lawrence's age. It will take at least another decade of pruning and rewiring to reach its full potential for multitasking. By then, Lawrence will have reached the age that Shakespeare reserves for sighing lovers and swearing soldiers. It's also the age of college students.

Ms. HAILLE ZUCKER (College Student): My name is Haille.

HAMILTON: Like Haille Zuker.

Ms. ZUCKER: I'm a student in the Department of Psychology. I'm 20.

HAMILTON: And she's really good at multitasking exercises like the one she's taking on a computer in Cindy Lustig's lab. An assistant gives instructions.

Unidentified Woman: If the shape is orange, you need to tell us which side is taller, and if it's gray, you just need to tell us which side has more bumps. So we won't change the rules on you anyway.

Ms. ZUCKER: OK. Good.

(Soundbite of laughter)

HAMILTON: The trick is to keep two tasks in mind at the same time. As the experiment progresses, Zucker has less and less time to respond by hitting the correct key. But she's not fazed.

Unidentified Woman: All right. A little more challenging, but a hundred percent still.

Ms. ZUCKER: OK.

HAMILTON: Zucker is probably near her peak for multitasking. Researcher Cindy Lustig says that's because the brain of someone in their 20s has an adult's capacity to oversee several tasks while retaining a child's ability to tune out distractions.

Professor LUSTIG: There's a reason that we, you know, have fighter pilots while they're in their 20s and 30s. That just seems to be when we're at our best for this sort of fluid intelligence and being able to switch back and forth between things, and so on and so forth.

HAMILTON: Of course there are also plenty of older fighter pilots. But over the decades, even the best multitaskers see their speed and accuracy gradually decline. So in addition to testing kids and college students, Lustig has been studying older people like Mary Bailey and her husband Al(ph) who've just arrived at the lab.

Professor LUSTIG: It's nice to see you guys too. This is Mary.

Unidentified Woman: Another Mary.

HAMILTON: Mary Bailey is 65. Al is 78. After saying hello, they each disappear into rooms where they do multitasking tests. When Mary Bailey comes out, she says the tests were tough.

Ms. MARY BAILEY: I don't think I could have done that testing unless I'd been really, really paying attention.

HAMILTON: She's probably not as good at multitasking as she used to be in the 1960s. That's when she worked as an army nurse at a field hospital in Vietnam.

Ms. BAILEY: Those who were close to dying, we sent to the chapel. The ones that could be helped, we would medicate, and they were sent off to wards. It was mind-boggling what you had to remember.

HAMILTON: And you had to switch from one task to another.

(Soundbite of snapping fingers)

HAMILTON: Just like that.

Ms. BAILEY: Absolutely. Yep.

HAMILTON: Lustig's research suggests that one important reason multitasking gets harder as we get older is that we're less able to tune out distractions.

Professor LUSTIG: Older adults may be more distracting themselves either by thinking about, oh, how am I doing on this, and oh, shoot, I just made a mistake, or thinking about, oh, I wonder how my granddaughter is doing. You know, they seem to have a lot more of this internal stuff going on.

HAMILTON: And Mrs. Bailey says that was part of her problem while taking the test.

Ms. BAILEY: I was aware that you all were out there because I could hear. I was aware that Mary, poor Mary, was sitting here while I went through this, and I would ask her a question or two. I mean, it must be terribly boring.

HAMILTON: Brain scans from the Lustig lab suggest that all this internal chatter gets in the way. So the frontal cortex has more trouble keeping focused on the tasks at hand. That may be why when we reach what Shakespeare called our second childishness, our multitasking skills start to resemble those of a child. Mary Bailey says at her age she's not concerned.

Ms. BAILEY: I'm able to make a choice to be focused, and I choose not to be focused on doing multiple things.

HAMILTON: Or as Shakespeare put it, to thy known self be true.

INSKEEP: Shakespeare is quoted by NPR's Jon Hamilton who's in our studios. And Jon, before you go, I want to mention some mail that we've received about your series on multitasking. We got a note from Jane Carter(ph) of New York City who complained that, in her view, some of your stories give the impression that men are better at multitasking than women. It's not that you said that, but there were some stories where you had men hunting and a lot of men in some of the earlier stories.

And she writes, "Just about every woman I know is better at multitasking than men." "Women," she says, "traditionally have a child at the breast, another couple of children tugging at her, and all the while she is cooking, cleaning, talking with friends and so on." So let's just put the question out there. Are women actually any better at multitasking than men?

HAMILTON: Well, the scientific evidence is not there to support that. There's no consistent evidence that gender helps you one way or the other. There's at least one study that suggested that women were better able to process two voices coming at the same time, understand what they are both saying...

INSKEEP: Oh, in a busy room, busy conversation.

HAMILTON: Right. That's just one study. And it's just one skill that's related to multitasking. So, not much there.

INSKEEP: Does it just really get down to the individual and how much practice you've had from those early stages of life?

HAMILTON: Practice in everything you do with your brain makes a difference. So one thing you could argue is that in a society where women may have more opportunities to multitask, more pressure to multitask with families and so on and kids - and this is often the example you hear - they are certainly getting a whole lot of multitasking practice.

INSKEEP: That's NPR's Jon Hamilton. This is one of, what, about 25 stories you're doing all at the same time, Jon?

HAMILTON: And while I'm answering email.

INSKEEP: Thanks very much.

(Soundbite of music)

INSKEEP: And we're not done examining your brain. If you'd like to see how you do on a facial recognition test, go to npr.org.

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