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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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  • by Dachannien (617929) on Saturday April 17, 2010 @07:45AM (#31880522)

    So how come I can't walk and chew gum at the same time?

  • by cavehobbit (652751) on Saturday April 17, 2010 @07:48AM (#31880530)
    7 projects, 2 of which are corporate mandates with no additional funding or 'resources' to do them, 4 other administrative tasks, plus an hour or so each day dedicated to HR-related corporate marionette-ing to satisfy the Political Correctness Police. All for 2 shell scripts and a mainframe extract. That took 3 months to get done. And this isn't even a government job.
  • Bullshit. (Score:5, Funny)

    by Anonymous Coward on Saturday April 17, 2010 @07:50AM (#31880536)

    I call bullshit. Right now, I'm replying to this Slashdot article from my cell phone, eating a quick breakfast, and driving my car in morning traffic. I'm doing all three with the utmost saf

    • Practice (Score:5, Insightful)

      by TheLink (130905) on Saturday April 17, 2010 @08:50AM (#31880870) Journal
      Seriously though, you might be able to learn how to do that if you could practice doing that 100 times every day, for a month under safe simulated conditions (e.g. driving simulator, and simulated eating too, otherwise you'd end up killing yourself by overeating ;) ).

      It's all about practice. Practice, practice, practice.

      The first time you drive a car (especially a manual), there are so many tasks.

      After a while of practice, your brain configures itself to automatically make those tasks into a subtask, and groups them all into one task - "driving".

      Of course some people may never be able to do it. But I think a high proportion of people can. And I bet there are some people who can learn to do it after very short time - just like some people can learn to juggle very quickly, and there was that recent article about supertaskers.

      I'm sure Michael Schumacher can eat breakfast and type on a cellphone and still do F1 laps faster than I can, when I'm just doing F1 laps (just driving, not eating or doing other stuff).

      The trouble with most people is they're trying to do "for real" without practicing _properly_. That's like trying to juggle chainsaws, without learning how to juggle balls first, and then gradually working your way up under controlled conditions.
      • 95+% of the time you can, but the problem is with something high stakes like driving you always have to be on the lookout for the unexpected. You cannot maintain full situational awareness while multi-tasking, thats that. If you want to text or eat or do whatever during your commute, just take the bus. It's what I do.
        • Re: (Score:3, Funny)

          by raynet (51803)

          I would think driving a bus while texting or eating would be even more dangerous.

          • Re: (Score:3, Funny)

            by Cylix (55374)

            I am little more concerned at the apparent theft of a vehicle. I hope there were at least no passengers on board.

        • Re: (Score:3, Insightful)

          by TheLink (130905)
          1) You don't need full situational awareness[1] while driving to be safer than the average driver. If we ever are going to officially allow some drivers to multitask, there better be a driving test where people have to prove that they are much better than the average driver while multitasking. Then we ( the average drivers) are far more likely to kill them than the other way round ;). I'd prefer it if every driver was required to take that test, even if they can't pass it (and don't have to for a normal lic
          • by russotto (537200)

            [2] I saw a video where a sword swallower said he had a bad accident when a bird sat on his shoulder unexpectedly. To me that shows he is very bad at prioritization for him to do what he does safely. When you have a sword swallowed in your throat, you do NOT turn your head no matter what. It's like the "pain box" test in Dune.

            I'd think that would be a matter of suppressing a reflex rather than conscious prioritization. There'd be a lot fewer Bene Gesserit if the gom jabber test candidate wasn't told what w

      • by pnewhook (788591)

        Sure. But that gets into repetitive muscle training that no longer requires a lot of conscious thought. Ever try and learn the piano? You only get good when you practice enough so your fingers 'automatically' go where you want them to. As soon as you start thinking about finger placement consciously, you miss tempo.

      • by JamesP (688957)
        <quote>It's all about practice. Practice, practice, practice.</quote>

        Also learn to steer with your chin, WHILE you're eating something...
      • Seriously though, you might be able to learn how to do that if you could practice doing that 100 times every day, for a month under safe simulated conditions (e.g. driving simulator, and simulated eating too, otherwise you'd end up killing yourself by overeating ;) ).

        It's all about practice. Practice, practice, practice.

        When I first started practicing driving, it seemed like a chaotic cloud of different tasks -- pedal, clutch, brake, steering wheel. With time, they seemed to "bundle" together into one single task, mentally treating the separate threads as one process. I think a certain amount of shared context is needed though. Things like "fiddle with radio" or "adjust GPS" still feel like a separate task, no matter how many times I do it.

        • Re: (Score:3, Interesting)

          by TheLink (130905)

          > 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

      • Re: (Score:3, Interesting)

        by mdarksbane (587589)

        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 th

  • by slashmojo (818930) on Saturday April 17, 2010 @07:53AM (#31880550)

    Is talking on the phone really a single task? Is cooking? Surely each of those is made up of countless sub-tasks even if you don't consciously think about them.

    • by Pharmboy (216950) on Saturday April 17, 2010 @08:12AM (#31880648) Journal

      Is talking on the phone really a single task? Is cooking? Surely each of those is made up of countless sub-tasks even if you don't consciously think about them.

      If you were just saying random words, then perhaps not. But if you are discussing the new project at work, or what little Johnny did at school, or even about sports, it requires pulling in previous experiences, remembering specific events, drawing conclusions, etc., which are "subroutines" in a single task, communicating. A phone conversation can actually take more brain power than driving down the highway. Think about it, when someone is driving and talking on the phone, it is obvious that the cell phone requires more attention than driving. As for being sub-tasks, all tasks are generally linear subtasks that would qualify as a single task.

      Perhaps that is why people tend to stray into the other lane when driving/talking on the cell. A third activity comes in or they have to fork a thought for consideration during the conversation, and they run out of brainpower/memory, so the least important activity (driving) gets swapped out for a second. Humans just need more RAM.

      How about that, a computer analog for a car problem, instead of the other way around!

      • I think the analogy would be humans need another processor. We could do for more RAM as well, but that is another issue.
        • by X0563511 (793323)

          We have plenty of storage. I'm thinking we could use some more on-die cache.

        • Re: (Score:3, Interesting)

          by BikeHelmet (1437881)

          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 UpnAtom (551727) on Saturday April 17, 2010 @08:32AM (#31880764) Homepage

      Especially in men, right brains don't talk. So that's exclusively left-brain.

      Driving (at least the direction & speed control) is right brain. The time it's most likely to engage your left brain is when you have to consciously think ie planning your route, adapting to unusual road conditions. Apart from that driving & talking is fairly easy for experienced drivers. Typically, drivers talk in a monotonous voice as inflection is right hemisphere.

      Try adding a column of figures eg restaurant bill and having a conversation at the same time - pretty damn hard because both are left brain. So there we're only single-tasking.

      I think what this research shows is that we use both sides of our brain when we're single-tasking. Some areas of the brain are very specialised but other areas can be trained to perform similar functions (for some people, the right hemisphere spelling a word would be an unnatural task). If we're doing two tasks for which different hemispheres of the brain can assigned one of the tasks, then the brain is quite adept at dividing up the workload.

      • by Sanat (702)

        Thanks for sharing your insights... I am left handed so spend most of my mind activity in the right side of the brain. Often times when I am multi-tasking such as talking while driving... I find that I constantly shift the focus between the two tasks.

        As an example if I was making a left turn in downtown St. Louis with all the one-way streets, crazy drivers, and pedestrians then I would stop talking while executing the turn. Once the turn is completed then I start talking again. I am the same way when debug

      • How far do you take the right/left hemisphere argument? Do you subscribe to a J. Jaynes [wikipedia.org] breakdown of a once bicameral mind? Has the language centric left hemisphere put a ring in the nose of an affective, right hemisphere?

        I can't see it that simply but YMMV.

    • by rolfwind (528248)

      Is talking on the phone really a single task? Is cooking? Surely each of those is made up of countless sub-tasks even if you don't consciously think about them.

      There are many challenges like this:

      Its impossible to spin your RIGHT leg in a clock wise possion and then rub your stomach with your RIGHT arm in a counter clockwise possisoneverytime you do it either your right leg or your right arm will start spinning the same way as the leg or arm

      Just try it. Stand up. Spin your right leg to the right. Then place

    • by daveime (1253762) on Saturday April 17, 2010 @09:53AM (#31881284)

      Is talking on the phone really a single task?

      According to Steve Jobs, a definitive "yes" (until version 4 is released anyway).

      • by iamhassi (659463)
        I know you're trying to be funny, but talking on the phone is the only thing the iPhone can currently multitask.
    • by iamhassi (659463)
      Is thinking how to reply to a slashdot post really a single task?
  • 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?

    • Re: (Score:3, Insightful)

      by Rogerborg (306625)
      Based on this research, it would appear that women are better at cooking and talking on the phone. Gasps of surprise, and film at 11, probably something with Renee Zellweger being charmingly quirky.
    • by WrongSizeGlass (838941) on Saturday April 17, 2010 @08:10AM (#31880636)

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

      I think the answer is obvious. Our two tasks are:
      1) Thinking about the woman we're are talking to
      2) Thinking about the other woman over there.

    • 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.

      • Next time a woman claims to be a better mutitasker because she is a woman point out that it's just an excuse for her inability to focus.

        Disclaimer: Don't try this stunt without a crotch protector.
  • Please define task (Score:5, Insightful)

    by houghi (78078) on Saturday April 17, 2010 @07:59AM (#31880572)

    I can eat, breath, type and read at the same time while listening to music.
    At these moments I am also thinking ahead of what I am going to do.

    Even typing could be considered doing several tasks at the same time. The sample of 'cooking' in the summery can be defined as multiple tasks. You are standing, you are tasting and smelling, you are planning of what to do next and probably stirring as well as looking.

    For a chef in a kitchen, cooking is also interacting with other people at the same time.
    For some people cooking is pressing the button on the microwave and waiting for the 'ting' of the machine.

    So what is a 'task'?

    • Re: (Score:2, Informative)

      by Skexis (1744642)
      If you require constant attention to keep breathing, you have bigger problems than defining a task. But from TFA:

      Koechlin and his colleagues had 32 subjects complete a letter-matching task while they had their brains scanned with functional magnetic resonance imaging (fMRI). The subjects saw uppercase letters on a screen and had to determine whether those letters were presented in the correct order to spell out a certain word. They were given money if they performed the task with no errors.
      ...
      But then they made the task more difficult. In addition to uppercase letters, the subjects were also presented with lowercase letters, and had to switch back and forth between matching the uppercase letters to spell out, say, T-A-B-L-E-T, and lowercase letters to spell out t-a-b-l-e-t.
      ...
      To make things even more complicated, the researchers introduced a third letter-matching task. Here, they saw the subject's accuracy drop considerably. It was as though, once each hemisphere was occupied with managing one task, there was nowhere for the third task to go.

  • 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 tomhath (637240)
      Yes, playing difficult music requires a lot of concentration. Now have the musician talk on the phone and solve a crossword puzzle while they're playing and see how well they do.
    • I was a drummer (Score:2, Interesting)

      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 folk

    • I suspect much depends on how you define 'thing'. While the organist in your example may appear to be doing many 'things', in truth they are all closely related and may not be treated by the brain as more than two 'things'.
       
      It may also be that organists are like air traffic controllers or NASA mission controllers - from the right hand side of the bell curve.

    • Re: (Score:3, Insightful)

      by phantomfive (622387)
      Reading the study (actually the summary), I think the problem is the people doing the test weren't actually switching tasks, they were trying to focus on all the things at the same time. I notice that when I work on multiple things (for example, music), I am actually switching between them very quickly. As an example, playing the piano and singing, it's like I queue up a line of words in my mind to sing, then switch instantly back to whatever my fingers need to do. You just get very good at switching betwe
  • And when I had a really busy day, at the same time, I was able to:
    1. Drive my car
    2. Eat my Subway
    3. Take a call with my cell phone (no hands free, I had the phone between my ear and shoulder)
    4. Take note of what my client was saying (I had a kneeboard)

    Of course, I was not able to hold the steering with my hands, but I was using my knee (was driving on the highway).

    So this is 4 tasks at a time. I never had an accident.

  • Maybe 2 tasks in the foreground but its useful to have your computer checking mail, RSS feeds, defragging, etc in the background.

  • Pick two (Score:5, Insightful)

    by characterZer0 (138196) on Saturday April 17, 2010 @08:11AM (#31880638)

    Thinking
    Talking
    Listening

    Pick two.

  • I'm glad to see this. There are way too many people in my business life claiming to be good at multitasking when their only real strength is never giving anything their full attention.

    It takes a certain amount of horsepower for your brain to help you get through a list of tasks, simple or not. When you focus, you get those things done faster, and usually at a higher quality.

  • by K. S. Kyosuke (729550) on Saturday April 17, 2010 @08:13AM (#31880660)
    So the three-app limit in Windows XP was scientifically justified!
  • by sonicmerlin (1505111) on Saturday April 17, 2010 @08:14AM (#31880662)

    I recall an article at Arstechnica about cell phone use while driving mentioning a study that found a minority of people are actually capable of multi-tasking while the rest are "bad at it". Oh yes, here we go:

    http://arstechnica.com/science/news/2010/03/rare-supertaskers-balance-driving-and-cellphone-use.ars

    • by dbIII (701233)
      Then again that's skewed by the sort of tasks that still get the job done when done very badly in comparison to when you concentrate.
      For instance typing in some sort of online chat while doing other things - nobody expects or cares about perfect spelling (just as they shouldn't care here), so a greatly reduced level of skill gets the job done.
      Driving is an incredibly bad example to choose because most driving tasks are very easy and a dangerously low level of skill for the few difficult parts is considered
  • by ThoughtMonster (1602047) on Saturday April 17, 2010 @08:16AM (#31880674) Homepage
    ...all the researchers are men and have never met any women.
  • Because I'm special. And superior to all other beings.
  • 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.

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

    • 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...

  • The small brain takes care of the mechanical movements of the body, such as walking, swimming, dancing, bicycling etc.

    As an aside, my brain is certainly restricted to a single task, since I'm an aspie.

  • by Webz (210489) on Saturday April 17, 2010 @08:51AM (#31880880)

    In my opinion, the type of task matters. And I think it has to do with what parts of your brain are used. For example, I can code/refactor and listen to a podcast just fine simultaneously. But if it's two comprehension-based tasks, like reading AND listening, I can't do them. Or lately I've even noticed I can't mentally elaborate on a thought and listen to a podcast at the same time.

    The coding and listening thing seems very left brain/right brain to me.

    Also, to the poster that mentioned musical multi-tasking... That's really interesting! But I think it helps that we as musicians have been training since a very young age to accept that level of multi-tasking, so the things that become muscle memory do. Fingering, breathing, sight reading, etc. Really the only thing that matters by show time is watching the conductor, the rest should be on semi auto pilot.

    • by Aranykai (1053846)

      I have been playing musical instruments since I was 6 years old. I have played many things from piano to trumpet to my current love, bass guitar. I find that I have little problem carrying on a conversation when I am playing a song I am familiar with, but when I am playing something new or something that requires improvisation, I cannot even carry on rudimentary conversation while playing.

      I have trouble even answering yes or no questions until I reach a point where I can rest for a short period in the song

  • by louzerr (97449) <Mr.Pete.Nelson@g m a i l.com> on Saturday April 17, 2010 @09:44AM (#31881218) Homepage

    I'm not sure if I ... hang on, that's my phone ... I'm not sure if I ... hold on, I've got an IM. But the study ... dammit! I give up!

  • by P-Nuts (592605) on Saturday April 17, 2010 @10:20AM (#31881462)

    So many posts bragging about being able to do a million different things at once. I don't think I can do two things at once. Once I get going I need a hardware interrupt to stop me. Usually it's the "desperately need to piss" interrupt.

  • How do people play RTSs then? Show me a good player of Warcraft, Starcraft or Supcomm and I'll show you a person that can manage at least half a dozen tasks simultaneously.
  • Have you ever tried to seriously concentrate on a single task at hand.

    * A Single vim/emacs session with a code or text. No Windows, No buffers.
    * Or a single webpage open and you are concentrating on that one only.

    You will switch only after one is over

    Compare this with the multiple buffers open with multiple tabs and multiple applications open, which you constantly switch back and forth. It may not take a genius to figure that the first one is 'more efficient'. This research substantiates that.

    I personally f

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