Unlimited Long-Term Memory, Limited Working Memory: What This Means for Learning
Try reading the following list, then covering it up and seeing how many you can remember: XCN, NPH, DFB, ICI, AES, PNX. How did you do? Most people would start to falter at the third chunk of letters, if not sooner.
Now, try doing the same for this list: X, CNN, PHD, FBI, CIA, ESPN, X. You’d probably get more chunks correct. But these are the same letters! The only difference is the spacing; now you can see chunks that are familiar to you [1].
This illustrates the relationship between working memory and long-term memory. You can hold more in your working memory when these items are linked to your long-term memory. In other words, what your brain is ready to process and learn right now depends on what you’ve already learned — the more you know, the more you can know.
Working memory is the “workspace” of things you’re holding in your attention at the moment. It’s clearly very limited. Sure, you can walk and talk on the phone at the same time, but if you’re giving detailed instructions for how to get to the hospital, you’ll probably pause the walking, and if you’re walking across a rickety bridge that could snap with any wrong step, you’ll probably pause the talking [2]. Every bit of focus taps into a tight resource in your brain.
Long-term memory, on the other hand, holds a huge amount of information, more than you can imagine. Brains aren’t like computers or filing cabinets with a certain amount of storage space, needing to delete things to free up room. Each memory is a network of connections that can be strengthened for a lifetime. If you’re a fluent English speaker, you’re never going to hear English as if it’s a foreign language. If you’ve learned what a zebra is, or even a horse, you’re never going to see a picture of a zebra and think, “What kind of creature is that?! I’ve never seen anything like it!” Every time you pay attention to something, how you process it is shaped by the contents of your long-term memory.
So when something held in your working memory contains information already held in your long-term memory, you’re retrieving it along with a whole network of things you’ve learned that are connected to it. When a complex web of knowledge can be retrieved as a single chunk, there’s more room in your limited workspace to focus and learn. This “chunking” is how experts draw upon what seems like impressive amounts of memory at a time. Skilled dancers may be making a lot of motions, one after the other, but to them, the “move” doesn’t feel like a lot to remember. All the pieces are tightly bundled together in long-term memory, so just activating the “move” activates them all.
Similarly, as you’re reading to learn, you’ll process it more deeply if your brain isn’t juggling a lot of unfamiliar information. The results of this basic experiment have been repeated many times: take an easy-to-understand article about a topic and show it to experts in the topic and people who aren’t experts, and later, the experts can better recall what they learned from it [1]. While the other readers had to process many new things, the experts had more mental space to focus on the important takeaways.
Clearly, learning isn’t just a transferable skill that some people are overall better at than others. (I can handle challenging science classes at a rigorous university, no problem, but apparently studying for the driver’s permit test is quite the struggle for me!) You’ll learn a topic better when your working memory isn’t overloaded — so if you don’t know much about the topic yet, start building the basics in your long-term memory, chunk by chunk.
[1]: Daniel T. Willingham, Why Don’t Students Like School? (Chapter 2: “How Can I Teach Students the Skills They Need When Standardized Tests Require Only Facts?”)
[2]: Gary Keller, The ONE Thing (Chapter 5: “Multitasking”)
