I have found that improving my understanding of human cognition — how thinking happens, what learning looks like in the human brain — helps me to better understand the learning that is happening or not happening in my classroom. The brain is complicated, and cognitive science has far more questions than answers. At the same time, there are things that cognitive science does understand. In communicating those ideas, metaphors are useful in illuminating how a theory plays out in practice.
I’m going to explore four metaphors for memory. Each is imperfect: each illustrates some principles and comes up short with others. I think that, together, they get at some core elements of thinking were not intuitive for me and can help to paint a rich picture of what is happening in students’ minds during classroom instruction. The first and third of these metaphors come from Dan Willingham in this blog post, which is well worth a read.
This model sets up the distinction between working memory and long-term memory. Working memory is where thinking happens, and long term memory is where knowledge and skills are accumulated. For information to enter long-term memory, it needs to go through working memory.
There are several shortcomings to this approach. One essential feature of cognition is that working memory is finite — we can only think about a few things at a time — while long-term memory is, as far as psychological science knows, infinite. At the same time, long-term memory is not just a database of information. The organization of information in long-term memory is essential, and knowledge that is chunked together effectively increases the capacity of long-term memory. Finally, working memory influences long-term memory. Every time we think about something, we influence that knowledge, which is not captured in the flowchart.
Another way to think of memory is to imagine the brain as a giant library, and thinking as a few flashlights shining on a certain areas of the library.
All knowledge is not created equal in this model, as the better organized the library is, the more information can be captured by the flashlights’ beams. It’s possible to know something and not be able to think about it if you’re unsure of where to shine the flashlight. It can also illustrate the limitations of what our minds are capable of. There are only a few flashlights, and if too many of those flashlights are searching for information or busy shining on something at one time, the mind gets overloaded. A central metaphor here is that thinking and memory are inextricably linked; they don’t happen in different places through different processes but are systems that are interconnected and working in parallel.
But this metaphor also falls short in important ways. It still does not get at the idea that thinking changes memory; thinking is not a passive flashlight shining but actually creates new knowledge and consolidates old knowledge. The library metaphor also further perpetuates the idea of memory as a static, inert database.
Hill of Sand
Think of a hill of sand—that’s your mind. You pour water on it—water is thought. The water coursing over the sand creates gullies and rivulets. That’s memory. It’s a representation of where the water (thought) has been in the past and if the water moves through those same channels they will become a little deeper. The next time you think (pour water) it will likely happen in the channels it’s followed before….but not necessarily. The new water also has the potential to change the gullies on the hill.
Long-term memory is what has been left behind by working memory; memory is the residue of thought. Every time you think about something, you both consolidate that knowledge further and change the nature of that knowledge. This metaphor emphasizes the connections between thinking and memory, and I think it says something powerful about the influence long-term memory has on thought. Those gullies that have been created by long-term memory guide all of future thinking, and can be thought of as our collection of beliefs, habits, and biases.
But this metaphor comes up short as well. Working memory capacity is finite; thinking of it as a stream of water can miss that point. A metaphor of cognition as a stream can miss the nuance of the connected networks of knowledge that make up useful and transferable skills. This metaphor also does not emphasize the difference between storage and retrieval; it’s possible to know something but not remember it at the time.
Stones in a Forest
A final metaphor I’d like to entertain is of memory as stones in a forest. As I walk around arranging and building memories with stones, I also wear paths from one place to another creating links between different memories or connecting new memories to old ones.
Memory as a forest captures a distinction between retrieval and storage that I think is important. Once I’ve created a memory — arranged some stones in the forest — that memory will be very slow to degrade. The path to and from the memory will become overgrown quickly if it is not used (that’s forgetting), but an old path will reappear quickly when it starts to be walked again. These paths also do something to emphasize how, if knowledge is not richly connected with broader ideas, it is unlikely to be useful, and it will be challenging to synthesize that knowledge with other, new ideas.
Of course this metaphor has weaknesses as well. Thinking influences memory. While this model captures the importance of revisiting memories over time, it does not get at the idea that memories themselves are changed through continued use. It also focuses more on the nature of long-term memory than the process of working memory and the interaction between them beyond wearing paths between memories.
Metaphors are useful, but they are also limited. I’m skeptical there exists an ideal metaphor for memory,, and each of these metaphors serves different functions and emphasizes different ideas while missing others. Together, they can create a useful understanding of how cognition occurs, but there’s plenty more left out. I’m sure some psychologists would say I’m missing the distinction between decision-making, auditory memory, and visual memory in my model of working memory. Others would argue that I’m oversimplifying chunking, the organization of knowledge, and the complexity of long-term memory. Many teachers would say that I am getting lost in theory without connecting it classroom actions. Others would say that I am focusing on memory at the expense of numerous other influences on students’ everyday learning. There are plenty more potential avenues for criticism.
But these metaphors serve a very specific purpose for me. As I think of memory through metaphors, I consolidate my understanding of my students’ thinking in new ways and organize it so the implications of that understanding are readily available as I teach. I think that these metaphors do contain some scientific accuracy, but my primary goal is for my knowledge to be useful for me in my teaching. I am constantly interpreting what happens in my classroom — the relationship between the learning experiences I design for students and the students’ learning, or lack thereof. If these metaphors can serve as a lens to understand why one strategy works or another strategy doesn’t, they have helped me to better understand my teaching and my students’ learning.
Dan Willingham’s blog post was my primary influence on this post. I also found these sources useful:
Robert Bjork on storage and retrieval
Anna Sfard on metaphors
John Sweller on Cognitive Load Theory