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Medicine Science

Research Suggests Brain Has a 2-Task Limit for Multitasking 257

Posted by timothy
from the typing-sleeping-being-hungry-so-there dept.
suraj.sun writes with a story from LiveScience about just how much attention you can devote to each of the tasks on hand that scream for it: "The brain is set up to manage two tasks, but not more, a new study suggests. That's because, when faced with two tasks, a part of the brain known as the medial prefrontal cortex (MFC) divides so that half of the region focuses on one task and the other half on the other task. This division of labor allows a person to keep track of two tasks pretty readily, but if you throw in a third, things get a bit muddled. 'What really the results show is that we can readily divide tasking. We can cook, and at the same time talk on the phone, and switch back and forth between these two activities,' said study researcher Etienne Koechlin of the Université Pierre et Marie Curie in Paris, France. 'However, we cannot multitask with more than two tasks.'"
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Research Suggests Brain Has a 2-Task Limit for Multitasking

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  • Musicians (Score:5, Interesting)

    by Landak (798221) <Landak@gmail.com> on Saturday April 17, 2010 @08:02AM (#31880592) Homepage
    What about professional musicians, who have to concentrate on far many more things than two at once? Organists, in addition to playing anything up to five keyboard manuals with their hands and one with their feet (simultaneously reading anything up to twelve lines of music, though in practice usually never more than five), have to listen to a choir and/or congregation, watch a conductor, and read the music, all at the same time. Some of them can even sing competently one line whilst doing so!

    Whilst I can accept that it is very difficult to consciously concentrate on more than two things at once, somehow some people can train their subconscious into doing so -- when sight-reading music, I experience a lovely sensation, almost as if my brain is being "split" down the middle -- if I concentrate for too long, I start to develop a headache and feel exceptionally exhausted. It is a most wonderful feeling, and nothing else in the world quite comes close (although doing some rewarding mathematics isn't far behind). I would not be surprised if it were possible to find many more examples of people concentrating on more than two things at once, "simply" through getting other bits of their brain to do the dirty work. Juggling on a unicycle while jumping over a skipping rope, anyone?
  • Re:Musicians (Score:4, Interesting)

    by cthugha (185672) on Saturday April 17, 2010 @08:17AM (#31880680)
    As I remember it, all of that repetitive fine motor control musicians need is handled by the cerebellum [wikipedia.org] at an unconscious or preconscious level once the necessary movements have been learnt (this is why practice is important). So yeah, there is division by delegation of many tasks, like you said, but I'm not sure how many pure "thinking" processes could be performed at any given time.
  • by geekmux (1040042) on Saturday April 17, 2010 @08:21AM (#31880714)

    Somewhere not so long ago I saw research article that pointed out women can multi-task better than men. And that it was a trait of women in general.

    Its a matter of dealing with kids.

    So if two is the limit, what does that say about men? Which head are they thinking with?

    My apologies if I call bullshit here. A "matter of dealing with kids" is your proof? And the women who don't have kids?

    It used to be that mens car insurance rates were MUCH higher than womens. Perhaps you should take a closer look at the rates today, since women think they can drive, put on makeup, and talk on the phone at the same time, and the insurance rates prove it. So does the side of my car.

  • Re:No. Just, no. (Score:4, Interesting)

    by dominious (1077089) on Saturday April 17, 2010 @08:59AM (#31880936)
    There is an example from R. Feynman, where he said he used to count the time in his head but he could not talk at the same time, whereas someone else could do that easily but he could not read a paper at the same time. OTOH Feynman could read the newspaper while counting time.

    What was the difference? Feynman was counting time by narrating the numbers in his head (using the speech system), while the other guy was picturing the numbers in his head (using the image system). So if he was using the speech system he could not speak at the same time because that system was already in use, while the other guy could not read because he was already using the image system.
  • by ultranova (717540) on Saturday April 17, 2010 @09:00AM (#31880946)

    I had an accident and the zone of my brain which is responsible for the communication between the two hemispheres of the brain (corpus callosum) was damaged during a important head injury. Now it's difficult to take notes while listening to a speaker for example because I need to concentrate on two tasks.

    Can the "other" hemisphere act on its own? I mean, is it more like having lost half your brain, or having been split into two beings in a single body?

    So both hemispheres need to work actively but what is more important is the communication between them

    Yes. I theorize that in order to meld separate nodes to a single entity, the communication between them has to be at least as fast as information processing within them. That way they stay so well synchronized and coordinated that they are, for all intents and purposes, a single entity - a brain, rather than just a bunch of neurons.

    This is important for AI research, since it implies that the current design of computers - fast processor, but huge cost of communication and cache misses - is as bad fit for AI as can be. Instead, you'd want lots and lots and lots of relatively weak cores with their own dedicated on-chip memory and capability of sending messages to each other.

    I wonder if graphis cards and compute shaders would fit the bill? They certainly are much better at parallelization. Of course, even then you'd need lots and lots and lots of them...

    Or just run the whole thing over the Internet. Let's add AI nodes to various P2P programs and see Skynet emerge :). Seriously, the burden on a single computer would be pretty low, so it should be technically doable...

  • I was a drummer (Score:2, Interesting)

    by AnonymousClown (1788472) on Saturday April 17, 2010 @09:17AM (#31881074)
    Playing a drumset requires both wrists and both feet moving, seemingly, at different times..

    It's really all one thing - one movement. In other words, my wrists and feet where acting synchronously to the beat. The position for each body part would be different but the timing was the same. Probably the most impressive drummer I've ever heard was Omar Hakim - drummed for Sting on "Dream of the Blue Turtles". Sometimes I wonder if that guy's hemispheres actually communicate. Which makes me wonder of those folks whose hemispheres were disconnected wouldn't be awesome drummers or piano players.

  • Re:Practice (Score:3, Interesting)

    by mdarksbane (587589) on Saturday April 17, 2010 @10:34AM (#31881578)

    Just from my own experience, it seems like there are a bunch of different things going on when you try to multitask.

    There are things you have practiced so much that your brain no longer has to think about them - like say, walking, or driving when there are no changes in the road or other cars. Let's call these "background processes" although in terms of computer architecture it's more like you've delegated the work to a specialized unit like a GPU. I can generally walk and do multiple things at once with the conscious part of your brain. The thing is that this requires the background process to be both well=practiced and unchanging. If the road ahead of you is empty, you can drive for miles without really consciously thinking about the road, sometimes even missing your exit by miles without realizing it. But if a deer jumps out or someone cuts in front of you, that part of your processing can't handle it, and you have to go back to the active part quickly or you're going to crash.

    I've also noticed something like what this article is talking about, where it seems like you're processing things in parallel, sort of like a multi-core system. You're just doing two active thinking things at once. Some people are better than others at this. Personally, when thinking in this mode, I have a hard time handling more than two things or so, as this article says I should, and my performance in both those tasks decreases. I've also noticed that certain types of tasks are harder to do this with - I only seem to be able to have one input and one output stream open at a time. Have you ever failed at talking to someone on the phone while writing something else (or listening to your wife while also reading slashdot)? If you're actively processing both at the same time, it can be pretty hard.

    But this is where I get to what people never seem to mention when they talk about multitasking, which is how I personally handle greater than 2 things at once. It's like a time-slicing model. There is a (sometimes large) portion of my attention that is thinking nothing but "do this task, then do this next task, then go back to this other task." Sometimes it's shorter slices than others. Like with the wife and slashdot model - I have to listen, then read a sentence while she pauses, then go back to listening. You sort of jump between each task quickly, get it back to a steady state, then jump to your other task and try to do some work on it before the last one needs attention again. As long as I am focusing on the multitasking queue and not too much on any individual task, I can do a lot of things this way, and I think it's how most people end up handling large numbers of tasks. The problem is first that there is a lot of overhead, and second that if you end up locking onto one task (and starving your scheduling thread, essentially) you can not realize how much time has passed and let the other tasks all go to shit. This is more of the driver who talks on his cell phone but is still actively paying attention to the road (instead of just going on autopilot) and will therefore occasionally miss bits of the conversation or shift lanes later than he is supposed to because he's thinking about remembering both of them.

    Does that sound familiar to anyone? Just realized that model has been floating in my head for forever, but I don't know if anyone else thinks that way.

  • Re:Bundling? (Score:3, Interesting)

    by TheLink (130905) on Saturday April 17, 2010 @11:20AM (#31881824) Journal

    > Things like "fiddle with radio" or "adjust GPS" still feel like a separate task, no matter how many times I do it.

    How many times have you actually _practiced_ it? You can't just do it a few times a day to get better at it. It has to become like walking to you, so that you don't think of the separate things to do to fiddle with the radio. You just think "radio channel #1" and it happens - the rest of your brain goes and does it.

    That said, some people never ever learn how to fly a conventional helicopter no matter how much they try and practice.

    And I guess most people will never get this good at tetris even if they practiced a lot:

    http://www.youtube.com/watch?v=jwC544Z37qo [youtube.com]

    Skip to about 2:50 and watch till the end where the "locked" blocks go invisible...

    He can probably play normal tetris while driving and talking on the phone. I'm assuming he can learn how to drive ;).

  • When you practice doing two tasks simultaneously, they become a new, single task. How do good drummers play syncopated beats? You learn a multitude of "keeping the beat" tasks involving many combinations of common patterns on the bass drum, hi-hat, and ride cymbal, then you learn a variety of syncopated beat tasks to play "overtop" of the other task. (You also have to learn strategies for performing these tasks at the same time, especially when you have to borrow a foot or hand from the keeping-the-beat task for an accentuated part and then un-borrow it; however, my point---namely, for a good drummer, many complex patterns involving multiple limbs, when practiced sufficiently, become simply "one task"---still stands.)

  • by Anonymous Coward on Saturday April 17, 2010 @03:10PM (#31883056)

    I have pretty severe ADD (diagnosed since childhood, have used various ADD medication, etc) and I am by far my most productive in situations where i need to multitask about 4 things. 1 is nearly impossible to do, 2 is not enough, and more than 6 starts to become difficult.

    It is important to note that the type of task - things that still remain impossible for me to multitask are include hard math problems, tracing bugs though code, and other things that require many linear steps with lots of temporary information in my working memory.

  • by Renraku (518261) on Saturday April 17, 2010 @03:18PM (#31883116) Homepage

    It's more about switching tasks than it is doing tasks at once. Imagine a normal person having to stack their working papers neatly, put them in a drawer with a file, and then close the drawer, every time they wanted to think about something not directly related to the task they're doing. For ADD people, they can actually just throw the papers on the desk or still hold them while answering the phone.

    Studies show that it takes about 5-10 minutes of work to get back into the flow of things and work at peak efficiency. A noisy phone ringing or baby crying will start this timer over again. ADD people can pick it up within a minute or a few seconds, but they have trouble doing one simple task all day.

  • by BikeHelmet (1437881) on Saturday April 17, 2010 @03:48PM (#31883262) Journal

    Humans seem to have about 4KB of RAM and one freaking huge hard drive.

    Think about it - the access latency matches up! ;)

    It should be noted that while we have a HyperThreading prefrontal cortex, we also have cores available doing background tasks, like managing movement, processing what we hear and see, alerting us to sudden movement/danger, etc.

  • by mswhippingboy (754599) on Saturday April 17, 2010 @06:29PM (#31884058)
    I'm sorry if this went past you. Let me explain this to you s l o w l y...
    iPhad is a play off of the iPhone & iPad platform with a double meaning. Remember "double entendre" from grade school?
    Say iPhad very slowly several times and maybe you'll get it - but then again maybe not.
    I don't even know why I'm responding to an AC (that's Anonymous Coward if you need an explanation of that as well), but since you appear to need spoon feeding; if you'll pay attention, posts on /. are initially set to Score:1 and either modded up or down - or ignored (in which case they stay Score:1) - by the moderators.
    However, I don't post here for the scores. I do it because I enjoy participating in the (occasional) interesting discussions and even the (more frequent) jousting of ideas and points of view.
    I will say though, posting as an AC will not garner you much respect because it shows you don't have the guts to put your identity behind your comment.

All this wheeling and dealing around, why, it isn't for money, it's for fun. Money's just the way we keep score. -- Henry Tyroon

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