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Effective Multitasking


Multitasking is one technique for ProductivityImprovement.


As humans evolve from mostly singletasking to mostly multitasking, it is helpful to document how to be as effective a multitasker as possible, as well as refute myths and pseudoscience spread by singletaskers who are fighting this inevitable evolutionary step.



Some rules for being more effective at multitasking:


  • Prefer IRL interactions to virtual interactions, e.g.
    • Prefer speaking to the people in front of you rather than the phone that is ringing, i.e. don't answer your cell phone while talking with people in person, let the person calling leave a message (or preferably send a text message instead, see CommunicationProtocols for more on that).


General Suggestions

  • Incrementalism - increase your multitasking load incrementally. That is, try doing 2 things at once before 3, and get good at 2 things before trying to get good at 3. Etc.
  • Learn limitations - When attempting to multitask, if you either fail to complete a task, or find that the task(s) are taking longer than they would if you did them sequentially (try them both ways if you can, repeatedly), note the set of things you were trying to do, put it in a section like "beyond current capabilities", and then try doing fewer of those things at the same time and see how you do.
  • Do long-wait tasks in parallel - Long wait tasks are tasks where you start them off, and then have to wait some amount of time for them to complete without interacting with them. E.g.
    • home maintenance machine tasks (dishes/dishwasher, laundry / washing machine & dryer)   
    • batch network tasks (uploading photos / downloading e.g. Software Updates (beware of UpgradesToAvoid))
    • printing
    • software installs e.g. Software Updates (beware of UpgradesToAvoid)


Specific Suggestions

Here are some simple multitasking task sets to try. All of these are fairly trivial and are based on first-hand successes. I'll add more as I think of them / do them.

  • start laundry, then do other things, then remember to check on laundry, move to dryer, etc.
  • start uploads (e.g. photos), then do other things, then continue with more uploads.
  • start a double-sided print-run, print one side, do other things, then flip the paper over and print side 2
  • some sample "other things" to do while waiting for laundry or uploads:
    • yoga, pilates or other workout (often takes about as much time as doing a load of laundry, thus is good for lowering cognitive load for timing / context-switching)
    • showering, or cleaning the house
  • start a software update (download + install) but beware of UpgradesToAvoid!
    • on a non-primary productivity computer
    • or on your primary productivity computer before going to take a shower
  • drop off a bicycle for a tune-up and get lunch/coffee to go (2011-123)
    • dropped off bicycle at Cognition cyclery to be tuned up (they estimated 15 minutes)
      • while waiting, walked to Le Boulanger and ordered a sandwich to go
        • while waiting for that, walked to Starbucks and got a coffee
          • processed email on BlackBerry while waiting for coffee
      • returned to Le Boulanger and sandwich was ready, packed it in bag
    • returned to Cognition Cyclery and bicycle was ready
    • end results:
      • elapsed time 15 minutes.
      • max 4 parallel multitasking: bicycle tune-up / lunch acquisition / coffee / email.
      • no idle wait for coffee, lunch, or tune-up.



Examples of *common* multitasking successes:

  • Video games. any kid playing a moderately complex simulated world video game (Sims, Civilization, Command & Conquer). In these games typically you must maintain, in realtime, multiple objectives across multiple areas of a "map". It's not easy to do at first, but by both watching others do it, and practicing it yourself, you can become increasingly good at it.  Pretty much anyone that has played these video games for at least a few hours is familiar with this experience of increasing skill in this particular example of multitasking.
  • Cooking. any chef preparing a multidish meal, etc. again, there are multiple objectives (multiple dishes) that a chef must prepare in real time, often with precise scheduling or syncing requirements. and again, anyone who cooks at home, and spends the hours developing the skills to cook one dish, then two (in series first, then in parallel), then three (similarly) is familiar with this experience of increasing skill in this particular example of multitasking.



It's important to be cognizant of possible limitations of multitasking. These tend to be of a personal nature, and sometimes of an aggregate nature, or experiential nature, i.e.

  • I (or any particular individual) might not be able to accomplish a particular set of tasks simultaneously (e.g. I can't juggle), but that doesn't mean that you or anybody else can't.
  • Some people might not be able to accomplish a particular set of tasks simultaneously (e.g. drive a manual transmission which requires multitasking/coordinating shifting, using the clutch, and gas pedals), but that doesn't mean that everybody can't.
  • Multithinking (trying to think about two things simultaneously, or attempt two tasks that require anything more than shallow cognition simultaneously). Most of the "studies" appear to show that multithinking is very difficult to do at all, and even those that attempt it supposedly perform worse than if they had serialized the cognitive tasks. Thus this deserves more study and experimentation in the development of learning techniques. Note that there *are* some examples of multithinking successes, e.g. simultaneous translators are known to use both halves of their brain in parallel to realtime understand what is said in one language and speak in another (without having what they say interfere with what they are hearing). Thus we should look to such examples to figure out what the brain is doing differently that enables efficient and even realtime multithinking.




Blog Posts




There are many misconceptions about what "multitasking" means.


The term "multitasking" was originally introduced to describe a computer operating system (OS) that could simultaneously run multiple processes or applications, then used as a metaphor and then broadened to include the concept of people simultaneously performing multiple tasks.


Unfortunately that broadening lost a bit of definitional precision which has led to a number of strawman arguments and examples (as provided by multitasking critics).



If we take the original OS definition of multitasking, note that it is possible for a computer to "multitask" even with a single-processor CPU (central processing unit) which itself is only executing a series of instructions one at a time (discounting pipelining for now, as multitasking operating systems, e.g. various unixes, did exist that ran on non-pipelined processors).


The key aspect of OS multitasking is about not blocking on I/O (input output), rather than instruction execution, that is the ability for an OS to continue processing *something* rather than waiting for any particular type of I/O.


By relating this aspect aspect of not blocking on I/O to human multitasking, it's possible to come up with a more specific, sensible, and implementable definition.


A very simple example of such multitasking is starting the laundry, then doing other things while waiting for the laundry to finish. You are multitasking because you are doing two things at once, that is, you are doing the laundry, and those other things.



Criticisms of Multitasking


Anti-multitasking studies and conclusions

There are many studies which either claim to (or are claimed to) prove that multitasking fails, that multitasking is impossible, that multitasking makes you less efficient, etc. E.g.


Anyone who wants to learn effective multitasking should read those articles and see if they can tell where the logical and methodological flaws are, and see if they can extract instances of possible limitations from such studies as worthy of being aware of.


examples used in criticisms

The following examples are provided in criticisms and thus may merit further study (or personal experiments) to determine how difficult (if possible) it is to effectively multitask across such sets of tasks.

  • browsing the Web and using other computer programs - could either be using multiple tools on one activity/project/task, or switching among multiple activities (even on a single web browser, e.g. with multiple tabs).
  • talk on (cell) phones while driving - typically cognitively disjoint tasks, the person/subject someone is talking to on the phone about rarely relates to the actual realtime driving task, perhaps only rarely incidentally if the phone conversation is regarding directions.
  • talk on phone while using computer - likely mitigated if used for the same focused activity/project/task/subject
  • homework while watching a movie 
  • instant messaging while doing homework
  • playing games online and watching TV
  • talking to someone in person while using/watching a device - e.g. computer, watch, phone, television, reading something.
  • pilot jumbo jets - is possible with training, thus evidence for multitasking as a (perhaps domain-specific) learnable skill
  • monitor air traffic - is also possible with training.
  • solving math problems or classifying geometric objects - used in 2001 study.
  • ...


concepts related to examples in criticisms

Some of the critical articles / studies extrapolate from examples to more general concepts worthy of study


potential limitations generalized from studies

There are a number of generalizations that can be drawn from the above studies and articles, and while we should scrutinize their logic and methodology (see below), we should also keep track of any apparent similar results in the studies that may indicate patterns of potential limitations worthy of study, or at least precaution.

  • cognitive context switching has high time costs. When you switch from one cognitive activity (project/task on a specific subject/topic) to another, it takes your brain time to refamiliarize itself with relevant context before it's able to reason/think/conclude/create efficiently on the second activity.
    • time costs increase with increasing complexity of activities being switched among
    • time costs increase when switching to new tasks (relatively unfamiliar)
  • high frequency cognitive context switching reduces cognitive capacity in the long term
  • practiced things may be multitaskable (thinks requiring no cognitive planning) - we "can do two things at once as long as one of them is something we've practiced so much that it doesn't require any sort of cognitive planning"
  • ...


logic/methodology flaws in criticisms

Straw man

Perhaps the most common logical flaw made by negative arguments (arguments that attempt to prove something doesn't doesn't work, is impossible, is a bad idea etc.) is the straw man fallacy. In short, an article sets up an artificially constructed example of the point they are arguing against, criticizes the artificial example, and then concludes that since they demonstrated that the artificial example fails, then so must the larger point they are arguing against.


Proof of a negative with negative examples

In short, you can't prove a negative by collecting a bunch of failures. Stronger than the straw man, but still logically flawed, is the proof of a negative with negative examples fallacy. I couldn't find a specific wikipedia article on it, but hasty generalization comes close.


There are no squares

Here is a simple example of an obviously false proof by negative:

  • Evidence: here are lots of examples of four sided polygons (rectangles, trapezoids) where the sides fail to be the same length!
  • Conclusion: therefore, it must be impossible to make a four sided polygon with sides that are the same length.

Clearly the existence of rhombuses (most often squares) disproves the false conclusion.

All you can conclude from the evidence is that there are some four sided polygons with inequal sides.

But some does not mean all.


Here is the similarly flawed outline of many anti-multitasking articles (like the Wired article) :

  • Evidence: here are lots of examples of multitasking where the multitaskers fail (under whatever metric)
  • Conclusion: therefore, it must be impossible to multitask!

Again, the conclusion is flawed.

However, also again, you can conclude from the evidence that there are some people who fail at some examples of multitasking.

And again, some does not mean all:

  • Just because *some* people fail at some multitasking doesn't mean *all* people do.
  • Just because some people fail at *some* examples of multitasking doesn't mean that they fail at *all* multitasking.


More specific analogies:


Motorcycling is impossible

If you took a random sample of people and put them on motorcycles, they would likely nearly all crash soon after getting going. Does this mean that motorcycling is impossible for people? No, it's just that few people can ride a motorcycle, and it typically requires training and practice to do well.


Flying a jet is impossible

If you took a random sample of people and had them try flying a jet plane, they would likely all fail to take off or crash. Does this mean flying a jet plane if impossible? No, it's just that very few people can fly a jet plane, and it requires A LOT of training and practice (in simulators, with a skilled co-pilot) to learn to do well.



Maybe multitasking requires training and practice as well.



Socio-cultural reactions

As multitasking breaks from established social-cultural conventions, it scares many people and makes them uncomfortable as well, causing them to often lash out irrationally. It is important to note and catalog these reactions, as well as calm refutations thereof, and then follow-up appropriately to the reactionary comments.


Continuous Partial Attention

When multitasking, it is often said that one is paying continuous partial attention to each task, but that phrase is both too narrow a framing, and has a (deliberate) negative bias against multitaskers.



of either this article, or me, or photographs thereof


    • ... 




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