Multitasking exacts a hefty mental performance penalty

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In a 2002 academic paper, Dr. Klaus Oberauer at the University of Potsdam wanted to see just how limited our working memories are. For background, working memory is your brain’s ability to store and process information in the short-term. It’s the memory you use every day when you’re at the grocery store when you’ve left your list at home. It’s the memory you use at parties after you’ve just met someone and exchanged names. It’s the memory you use when you’re writing an email or updating slides in a presentation from a spreadsheet you just closed…

… and it’s incredibly volatile. Dr. Oberauer did extensive research that eventually broke what we call working memory into three discrete kinds of brain operations: background data, foreground data, and center of attention (focus). Background working memory is information that’s partially rooted in our long-term memory. When you see a corporate logo, you can immediately fish up relevant information from your longer-term memory about what that logo means to you. Foreground data is information you keep in your head for immediate processing, and one item in the foreground data is specially selected by the brain for the actual processing:


In his research, Dr. Oberauer looked at what made working memory operate less or more efficiently, and one of the findings of his research was that our brains apply “tags” or “markers” to the items in working memory that allow us to recall information very quickly in order to process it. Imagine if you were a primitive hunter on the savannah. You’d want to pay attention to your immediate surroundings and the lion in front of you that wants to eat you. Even while you keep an eye on the lion, your working memory assigns tags such as stumbling hazards on the ground so that you don’t have to divert your attention very long from the lion to walk around. If you had to reload all of your working memory from scratch each time, you’d incur significant cognitive delays, during which the lion would dine on you.

However, if you have multiple similar tags, your brain gets confused as some memory tags will overwrite others. A simple example of this is what happens when you try to write while someone is talking to you or the television is on. Your brain will sometimes confuse the data in working memory and you’ll accidentally write what you saw on TV versus what you intended to write. You can have multiple sets of different, discrete tags as long as they don’t overlap; for example, you can remember a phone number and the last song you heard on the radio because your brain doesn’t need to process them together. Try to remember two phone numbers or a phone number and a nine-digit postal code, and you’ve got a recipe for mixups.

So what does this have to do with multitasking? Does this look at all familiar?


Here’s the problem with this environment. So many of these different tabs and reminders open are of very similar nature. They’re highly likely to overwrite each other, which means you will incur a significant mental processing delay every time you tab to something else or get interrupted by another reminder. Your brain, instead of being able to keep its working memory sorted out and organized with discrete memory tags, will instead get everything jumbled all of the time, and you’ll instead be constantly having to reload from background data. The moment you find that you’re asking yourself, “What was I doing?”, you know you’re reloading from background data, because foreground data access is almost instantaneous.

The solution? Shut everything down as often as possible. Browse one item at a time, read one email at a time. Turn off preview modes. Turn off notifications. Turn off anything that’s going to risk overwriting your short term memory tags, and you’ll be able to access your foreground data working memory much faster, get more done, and feel much less frustrated.

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3 responses to “Multitasking exacts a hefty mental performance penalty”

  1. Well, you knew I’d love this! For further reading on the idea of memory tags, you may want to check out a new book from April, “Make it Stick: The Science of Successful Learning.” Those tags (that book calls them “cues”) can be used quite intentionally, both to induce new learning, and importantly, when you’re trying to UNlearn something (as in when you need to replace one process with another).

  2. Watching my youngest study (for his 3rd degree) confounds me, and does not sit comfortably with the info in the post, to which I can relate absolutely.
    He studies with music on, and usually something visual going simultaneously, and still still does OK.
    How is that possible?? I have never understood it, requiring a benign environment of at best white noise for my own concentration.
    Is it some sort of digital rapid evolution going on amongst these millennials??

  3. My mom has been telling me FOR YEARS that multi-tasking is bad. Maybe I need to (finally) listen to her? Crap.

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