Productivity Tip: Multitasking slows you down

The picture says it all. Multitasking really slows you down. Suppose you have two tasks to do: Task A and Task B. When you perform your tasks alternately (as in the top line) you pay a big overhead cost. Each time you are resuming a task, you have to load all the information related to it into your head and to enter into the state of mind that you had been when you last stopped doing it. This overhead is known in computer science as context switch.

When you work on each task until it is done (bottom line), you save yourself the context switch overhead. And therefore you are able to finish earlier. Each of the tasks on the bottom line is completed before the corresponding task on the first row. By the deadline (finish time), you had completed both tasks and even had time to rest (the blue arrow).

I prefer to manage my work as in the second row. When I work on a software project, I always get into my working room knowing that I am on the task until it is done. After several minutes, my mind enters the world of the project I am doing. I can’t hear or see anything not related to it. I totally live it.

And before I notice, the task is done.

So why do people multitask?

Sometimes there is a need to show progress in two tasks. In that case, you can’t avoid switching between them. Sometimes you just can’t progress on a task until you get additional inputs on it and then it makes sense to switch to the other one.

Some people choose to multitask whenever one of the tasks becomes boring or they just don’t want to do it. It is like doing it in very small steps, where each step is bearable. But then, they spend on each and every step the overhead of switching to the task that they don’t enjoy doing. Quite weird, since with this strategy they end up spending more time on the things they don’t like. The solution is obvious. Allocate enough time and finish with the things you don’t enjoy doing at once!

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10 Responses to Productivity Tip: Multitasking slows you down

  1. Alex Goad says:

    Good Stuff, your graph really makes it sink in.

    I have to say I agree with you nearly all the way. If people focused on one task the way you mention, not only would they finish faster, but they would have a better chance of finishing in the first place.

    (I come from a self-employed background where finishing can be optional)

    On the other hand, when I write long reports or short books, in shots of 10-15 pages a day, I find I have to switch to something else after a time or I start losing the edge…

    You software developers are hard to beat when it comes to focus…

  2. The same context switching logic can also be applied to interruptions and their impact on productivity.

    I used work in a cubicle-farm and I would start my day a few hours after most of the other folks in my area – partially because I’m a night owl – and then stay later so I could actually get some work done. The number of interruptions dropped significantly after 6:00 pm, and as a result my productivity scaled!

  3. thesamet says:

    It’s impossible to do any programming in an environment with lots of interruptions. When coding, a programmer has a lots of data loaded in his mind: scope of variables, names of functions, state of the program and so on. It is like a tower of cards perfectly built in his mind.

    When someone enters the room and asks “where did you buy this cool jeans?” the entire tower collapse in his mind. And entering the same state of mind again takes time.

  4. Tom Welsh says:

    Mihaly Csikszentmihalyi came to similar conclusions in his work on “flow” (several books). It takes the mind some time (up to an hour or even more) to reach ideal working conditions. But a single interruption, no matter how brief, can land you right back where you began. That’s why people engaged in important creative work need to be protected against interruptions.

    What often doesn’t emerge from discussions among developers is that flow is hardly relevant to “people-facing” activities. That’s why a salesman usually seems happy to chat to many different people in a short time. He does not need to think deeply, but is instead engaged in natural and pleasurable conversation (and possibly persuasion). These are tasks for which the human brain evolved, and most people find them easy and undemanding. Likewise politicians.

    Another motive for multitasking (especially when ostentatious) is as a form of bragging. You can show the boss, clients, or whomever that you are able to juggle many tasks with complete control and aplomb. If applicable, you can also demonstrate that you are not one of those strange “geeks” who need to retreat into a room and wear headphones in order to accomplish anything!

  5. roger pack says:

    With me taking a break every so often really helps. Also with some tasks you have to start them and ‘let them go’ in which case context switching is still the best bet.
    Also when I tried to unsubscribe to comments via email of another post on your site, it returned me

    _____@gmail.com is not subscribed to any posts on this site. [i.e. it didn’t work]
    Thanks!
    -Roger

  6. Multitasking slows us down. Multitaskers experience only an illusion of productivity. They feel they are doing a lot, when in fact all they are doing is constantly stopping and restarting. They completing very little at all.

    To learn more about the effects of multitasking, take my free exercise at http://www.davecrenshaw.com/exercise

  7. Dorothy says:

    and developing vaouirs cognitivea0abilities, such as memory and attention. This new game is called Brain Shift, and reflects in some way our ability (or inability as I discovered of myself!) to multi-task.

  8. It could be a good add on, but its strength is also its weakness; it is very subjective and very much at the mercy of human beings and their personal biases. There are some very conscientious folks over there, and there are (or at least there WERE) some folks with a bad attitude. I prefer to make my own judgments and I prefer that the tools to help me do it operate on unbiased criteria and algorithms.Holly Jahangiri recently posted..

  9. Beh, Simone, che dire? Peccato! Comunque mi permetto di dubitare che tu abbia davvero meditato i dogmi mariani. Forse, ti sei limitato a meditare come disfartene, proprio perché troppo ingombranti per chi ha già deciso l’opzione agnostica.

  10. Brigantaggio, purtroppo, è diventata la parola comune per designare un fenomeno che non fu affatto di brigantaggio. Però usare il termine “mercenari” oggi, a guerra finita da 150 anni, è storicamente un po’ improprio. O no?

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