Cognitive Load


After six miles of trekking uphill, we had finally made it to the top of the mountain. Sitting to rest our feet, Lars and I gazed down upon a beautiful alpine lake. With a sheepish grin on his face, Lars turned to me and said, “You should look inside your backpack.” Puzzled, I unzipped my pack and discovered about ten pounds of rocks. “I snuck those in there the first time we stopped!” Lars said, laughing. That was five miles ago.

Back then, I lived in the mountains and was a very fast hiker. Lars, ever the prankster, didn’t want to be gasping for breath all day. He knew I could carry the rocks without consciously noticing, but that they would slow me down a little.

Likewise, most people carry around extra weight in their minds, but instead of being duped into carrying that weight by friends, people are unknowingly putting the rocks into their own backpacks. They’re not consciously aware of it, but the added strain is slowing them down.

One of the recurring themes in tutoring work is the idea of cognitive load, which refers to the amount of energy being used by the brain at any given moment. Doing schoolwork, staying organized, and navigating the social world are all cognitively demanding tasks that require brainpower. Every item we have to keep track of, every detail we hold in consciousness, and every idea we are trying to use in a given moment adds to our cognitive load.

too heavy

I need to make a quick distinction between the impairment caused by excess cognitive load and the value of brain exercise. Both concepts arise from the simple truth that the brain is like a bunch of muscles. Challenging the brain makes it stronger, but needlessly overloading the brain is not beneficial. Taking on too much cognitive load causes unneeded stress and hinders performance. We want to save our strength for those challenges that are worthwhile: paying attention, problem-solving, and planning ahead.

rocks in your backpack

One of the most common mistakes students make is choosing not to take steps to reduce their cognitive load. Most students, in fact, go through school carrying a heavy load that could easily be lightened. Doing so is a classic example of making school harder than it needs to be.

Students can carry a heavy cognitive load, but it inevitably slows them down and hurts their performance. And unlike carrying extra weight in your backpack, carrying around an excessive mental burden doesn’t make you stronger; it only wears you out, leaving you with less energy to use for learning. And whether you realize it or not, that energy drain has an emotional cost. A heavy cognitive load makes you feel discouraged.

Are you, as a student, putting rocks into your own backpack? Let’s find out.

Here are some of the most common ways students choose to carry a heavier cognitive load than they have to:

  • Doing math problems in your head, rather than writing down the numbers and steps.
  • Attempting to write an essay without first brainstorming and outlining.
  • Not underlining key parts of questions and instructions.
  • Not crossing off the obviously wrong answers on a multiple choice test.
  • Not utilizing a calendar, a planner, or a to-do list.
  • Allowing your backpack or binder to descend into chaos.

Taking steps to reduce your cognitive load is one of the fundamentals of successful student psychology. To understand why, we’ll have to learn a little about how the human brain works.

Working Memory

The ability to hold new information in our minds used to be called “short-term memory,” but it’s now called working memory. The new term is superior because it implies, quite correctly, that work must be done to keep new ideas or details in mind.1


If I tell you to remember this string of numbers–8, 4, 7, 1–you’ll be able to do so for as long as you do something to keep them from slipping out of your consciousness. The most common strategy is to repeat them aloud or mentally repeat them, saying to yourself: “8, 4, 7, 1.” As long as you keep doing that, you can remember the numbers. But if you get interrupted by, say, a phone call, and I ask you to repeat the numbers after your phone call ends, you’ll almost certainly have forgotten.

It takes work to keep anything new in the mind. In this way, working memory is just like juggling: To keep the balls in the air, you have to stay focused and continuously put energy into the system.1

Fittingly, when people say they’ve “dropped the ball,” they’re often referring to a failure of working memory.

Humans have, on average, on a good day, just four working memory slots. Anyone over the age of 30 is likely to be thinking, “Hey! I thought we could hold seven things in short-term memory!” That’s what we used to think. More recent and more rigorous research has shown that for most people, most of the time, we only get four.1

Also, note how I said that we get four working memory slots on a good day. Working memory is diminished from four slots to three or two or even one when we’re under great stress, exhausted, or distracted.1 In a panicked, fight-or-flight mode, we probably have no working memory at all. Under less-than-ideal circumstances, it is extremely important to be aware of your diminished capacity for mental juggling so that you’ll remember to use strategies that reduce your cognitive load.

As tutors, we often draw a rough sketch of the following diagram in our notes:

Working Memory Blank

Did you figure it out? It’s a brain. This crude drawing is inspired by the work of Dr. Barbara Oakley, author of A Mind for Numbers: How to Excel at Math and Science (Even If You Flunked Algebra) and co-creator of the Coursera on Learning How to Learn.1

Anatomically, the drawing is all wrong, of course, but functionally, it is spot-on. It is a visual reminder of the fact that while we may have a huge bank of long-term memories to draw upon, we can only play with four ideas at once.1 If the four working memory slots are filled with the details of our current situation, then we might fail to remember something that we know.


The knowledge we have stored in long-term memory tries to get into working memory, but because all the slots are already filled, it can’t be accessed.1

More often than not, the brain drawing is a short-hand in our notes for a student who is struggling with math problems because he has chosen to do them in his head.

Mental Math

We see this difficulty with all sorts of math problems, and, indeed, in many subjects other than math, but the problem type where I see this most often is dividing fractions.

A student who has learned how to divide fractions, understands the procedure, and has practiced it enough times to have a decent memory of it will often be overconfident about his ability to solve such a problem in his head. Let’s use the following example: 6/7 ÷ 9/4

The procedure is that you leave the first fraction as it is, flip the second fraction, and the multiply straight across.

6/7 ÷ 9/4 = 6/7 x 4/9 = (6×4)/(7×9)

The correct answer before simplifying is 24/63, but many students will tell you that it’s 54/28 because they forget to flip the second fraction before multiplying. Others will remember that you’re supposed to flip it, but then they’ll forget how to multiply fractions. And others will remember all the right procedures but make a mistake in the final arithmetic. All of these students are suffering from an excess of cognitive load.

They know how to divide fractions. They’ve practiced the procedure on paper and done it correctly. All the tools are in their long-term memory. But because this problem type offers four numbers and three math symbols, it overloads working memory’s four slots. Because all the slots are filled, various aspects of long-term memory cannot be accessed.

Nine times out of ten, if a student messes this problem up while trying to do it in his head, and I have him write out the problem on paper, he then gets it right with no further instruction. As soon as he uses the strategy of writing to free up some working memory slots, he’s able to remember.

It’s as though pencil and paper make us instantly smarter. In fact, that’s exactly what they do.

Why We Write

By writing, we expand our brains beyond the confines of our skulls to include the pages we’re writing on. To be sure, the human brain is already quite powerful, but the world we’ve designed for ourselves is so demanding that we cannot succeed without writing. Hard problems require powerful strategies. Writing is the single, most powerful strategy we can use to become better at creative problem-solving.

Because creativity often occurs when ideas are manipulated and combined by working memory,1 writing greatly expands our potential to be creative. If you were to trace the history of human creativity alongside the evolution of writing and printing technology, as Robert Wright did in Nonzero: The Logic of Human Destiny, you’d find that innovation accelerated after each improvement in the tools of writing.2 We can be creative without writing, but we are much more creative when we write.

In his landmark book, Creativity: The Psychology of Discovery and Invention, Mihaly Csikszentmihalyi explains how writing can translate “fragile thoughts” into concrete ones, and in the process, reveal hidden truths.3 I regularly experience this. When I begin writing, I often have only a vague sense of what I’d like to say. Then, as I’m attempting to put my half-baked thoughts into words, the ideas gain clarity and come to life on the page, fully formed. I often surprise myself with the insights that I have while writing. Topics I hadn’t entirely understood while I was simply thinking about them suddenly make perfect sense. For the exact same reason, journaling can help you sort out challenges in your personal life.

To be clear, my process is never to just sit down and write a piece from start to finish. I always begin by dumping my thoughts onto the page in no particular order, without regard for grammar or style. Next, I sort those thoughts into categories. Then, I organize those categories into an outline. As this is happening, more thoughts often arise, and so more ideas get dumped into the document. Sometimes the categorizations change, and often the outline gets adjusted as time goes on. Finally, I begin to write in earnest. At each stage in my process, I am transferring as much as possible from my brain to the page in order to lighten my cognitive load. By doing so, I am able to gain greater and greater clarity about what the final product will be.

I often coach students with writer’s block on this very process. Many students approach essay-writing with a one-and-done, finished-product mindset; they think they should just be able to start writing their final draft from scratch without brainstorming or outlining. Of course, this is impossible for most people. Articulating how you feel about a complicated topic overloads working memory because there is simply too much to consider and too much to say. Step one is taking the ideas from your mind and placing them onto the page without filtering or formatting. The difficult process of writing an essay cannot proceed until we have taken steps toward lightening our cognitive load.

Some forgo the use of paper out of stubborn pride. To insist that you are special and do not need to use proven strategies is to fail to give yourself permission to be human. Others think they’re taking a shortcut. They refuse to engage with a writing process or showing work on paper for math problems because they think that writing will be more work. In reality, however, it turns out to be a great deal more work to not use paper. Writing feels like it will be extra work, but it actually lightens our load.

Look at this truck:


If something were to go wrong, the reason why would be obvious: The truck is overloaded. When a student is struggling with a math problem or an essay, the reason is often the same. The student’s load, however, is invisible; it is in his mind.

Organization and Planning

It is possible to get through school without any sort of organizational system. You can have a binder that is a chaotic jumble of unsorted papers and still get your work in on time. You can remember when tests are without writing them down in a planner. You can remember your appointments without an electronic calendar synced to your smartphone.

But there’s a difference between can and should.

If you always have to hunt through the mass of papers in your binder to find your homework because you don’t sort the papers as they come, you’re forcing your brain to do a great deal of unnecessary work. If you’re going from class to class holding in your head all of the due dates for assignments and the dates of upcoming test, you’re massively increasing your cognitive load. As a result, your ability to learn will suffer.


Although I’ve focused on the issue of students carrying excess cognitive load, the problem is just as common among adults. Most adults have developed a better set of strategies around reducing their cognitive load, but at the same time, most adults are burdened with many more responsibilities. For the sake of their own sanity and success, adults have an enormous need to manage cognitive load.

Perhaps more importantly, most adults are engaged in some form or another of leadership. Managers, teachers, and parents are role models for employees, students, and children. It is critically important for adults in these roles to lead by example and actively demonstrate the use of strategies to reduce cognitive load.

Leave the Rocks Behind

We all have mountains to climb, and we all must carry a heavy load. The challenges we face in life are hard enough on their own. There’s no need to carry rocks in your backpack.

Works Cited

1 Oakley, Barbara. A Mind for Numbers: How to Excel at Math and Science (Even if you Flunked Algebra). Penguin, 2014.

2 Wright, Robert. Nonzero: The Logic of Human Destiny. Vintage Books, 2000.

3 Csikszentmihalyi, Mihaly. Creativity: The Psychology of Discovery and Invention. Harper Perennial, 1997.

Image Credits

Title Image: Levent-Levi, Tsahi. “WebRTC is hard.” Creative Commons 2.0. Text added.

Weight Lifter: CrossfitPaleoDietFitnessClasses. “Good example of Crossfit Weight lifting – In Crossfit Always lift until you reach the point of Failure or you tear something.” Creative Commons 2.0.

Student With Heavy Backpack: faungg’s photos. “Going to school.” Creative Commons 2.0.

Juggling: Kris. “Juggles.” Creative Commons 2.0.

Brain Diagrams: Loper, Chris. “Working Memory” and “Working Memory Full.” June 24, 2016. Inspired by the work of Dr. Barbara Oakley.

Overloaded Truck: Wazir, Omer. “Overload.” Creative Commons 2.0.

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