Memory is often unconsciously understood to be like a library where memories, like books, are thought to be inserted and stored in some shelf-like areas of the brain. If we want to add to what we know, we just slot more information onto the shelves… If we want to access memories, we simply take a book from the shelf and thumb through it for the information we need, reinserting it when we’re done…
What are the problems with viewing memory in this way?
Here’s one:
It leads us to think of memories as being static and inert, waiting to be activated (a misleading verb I use a lot when describing memory).
What’s wrong with the verb ‘activating’?
‘Activating’ memory is actually ‘reconstructing’ memory
In the strictest sense, we do activate memories: I wasn’t thinking about crisps a moment ago and now I’m thinking about crisps = I’ve activated the idea of crisps.
But the problem with the verb ‘activate’ is that it gives the impression memories are just sitting quietly, waiting to be sparked and when they are, they come off the shelf just as they were put on.
In fact…
Memories are not just taken off a shelf.
‘Activated’ conceals a richer story. What is that story?
Whereas information in a book stays the same whatever context you decide to read it in (night/day/when you’re paying attention as you read it/when you’re not), this is not the same with our memories. Context matters for memory.
When we activate a memory, we do so in context:
An internal context – what else we are thinking about/feeling,
An external context – our home/the classroom,
And in response to cues, e.g. something the teacher says/an internal thought.
When you activate a memory, you aren’t just taking it off the shelf as it was, you are actually changing it. You are imbuing it with contextual details.
The more you activate the memory in different contexts and in relation to different cues, the more it becomes associated with different information. This makes it easier to access in various situations because many different cues will trigger the memory.
After retrieving the memory in many different contexts it becomes wrapped in a composite of contextual cues (Karpicke et al., 2014) and can be used in many different ways. This enables us to recognise new situations with similar contextual cues where this knowledge will be useful to us. This is often called transfer: “the use of prior knowledge in a new context” (Pan & Rickard, 2018, p.711).
It’s therefore less that we activate memories and more that we reconstruct memories, changing them in light of new contextual information. The book isn’t taken off the shelf just as it was – in fact, parts get rewritten.
In summary: when you recall, you reconstruct (Bridge & Paller, 2012; Loftus, 2017; Ye et al., 2020).
Let’s take an example:
Imagine students are learning about perimeter in maths. First, they see the example of perimeter around a rectangle (a football pitch perhaps). They learn to calculate the distance. ‘Perimeter’ becomes synonymous with ‘distance around a rectangle’.
Over the next few lessons and homework activities, they encounter perimeter in different contexts and in relation to different shapes. Their core idea of perimeter becomes far more transferable as they can now spot multiple situations where it can be calculated.
Eventually, even worded questions that do not contain the word perimeter still trigger the idea of perimeter if they are implicitly asking for the distance around something.
This signals a growing expertise: students who can use their knowledge in multiple situations.
What does this mean for teaching?
The core ideas we need students to know also need to be transferable to new situations. Seeing ourselves as attempting to ‘activate’ students’ ideas implies students are just taking them out of their minds ‘off the shelf’. Recognising that when students activate their memories they are actually reconstructing them forces us to carefully consider the contexts in which they activate them.
Let’s look at two things this might mean for our teaching:
(1) Rethinking retrieval
This might change the way we use retrieval practice in our lessons for example. Perhaps my students tend to start my lessons with five random retrieval questions unrelated to the rest of the lesson e.g. retrieving information on the Weimar Republic (the last topic we studied) before the main part of a lesson on medicine in the ancient world. I do this because I know spacing retrieval is a good idea and it’s been a while since the last topic.
Knowing that retrieving reconstructs students’ memories in light of the context they are in, I may decide that retrieving knowledge on one topic just before starting another topic might reconstruct their knowledge in ways I don’t want. Instead, I decide ask students to retrieve ideas that will become relevant to the lesson.
Or, perhaps I decide it’s fine to have retrieval on a topic disconnected from the rest of the lesson as, in my class, we always treat the beginning of the lesson as separate from the main part of the lesson. Still though, knowing that retrieval is reconstruction not just activation, I decide that I’ll carefully construct my questions to interleave potentially confusable concepts. This will cause students to think about the two concepts in the same context, compare them and better understand them.
Because I know retrieval reconstructs memory in light of the context, I’m considering not just what knowledge I’m activating but in what context.
(2) Considering micro and macro context
We can think of context as micro and macro.
Micro contexts are the various ways we plan for students to engage with the same idea at the same level of generality. The perimeter example is us thinking about the different micro contexts: which shapes should I plan for students to apply this core idea of perimeter too?
Another example is teaching covalent bonding in science: in relation to which molecules? Perhaps O2, H2O, CH4 then maybe HCl, C2H4 etc. (Tratt, 2023).
Macro context is the wider contextualisation of the knowledge. For example, we want students to understand that Macbeth is a Shakespearean play but also that it is part of a wider context of plays called tragedies that also includes Romeo and Juliet, Hamlet, Othello, King Lear etc. This helps them relate Macbeth to other plays by situating it in a wider related context (tragedies). It prevents the compartmentalisation of knowledge where students can only list the Shakespeare plays but not relate them to one another. This means that before I teach Macbeth and continually during, I help students make links to the idea of tragedy. I teach the play in this wider macro context and this helps them form links to other tragedies.
So when we plan curricula and lessons, we plan for both the micro and the macro context we need pupils to reconstruct their memories with. This helps guide the selection of the macro content and the micro examples.
If we simply think of ourselves as activating students’ ideas, it doesn’t matter which contexts we pick. We see activation as the goal, when really, it’s intentional reconstruction.
Further reading
Kristian Still, who I’m lucky enough to talk to from time to time, also blogs about the dynamic nature of memory.
References
Bridge, D. J., & Paller, K. A. (2012). Neural correlates of reactivation and retrieval-induced distortion. Journal of Neuroscience, 32(35), 12144-12151.
Karpicke, J. D., Lehman, M., & Aue, W. R. (2014). Retrieval-based learning: An episodic context account. In B. H. Ross (Ed.), Psychology of learning and motivation (Vol. 61, pp. 237–284). San Diego, CA: Elsevier Academic Press.
Loftus, E. F. (2017). Eavesdropping on memory. Annual review of psychology, 68, 1-18.
Pan, S. C., & Rickard, T. C. (2018). Transfer of test-enhanced learning: Meta-analytic review and synthesis. Psychological bulletin, 144(7), 710.
Tratt, J. (2023). In conversation with Jess Tratt @jess_tratt (former head of faculty for science and senior leader; currently teacher educator).
Ye, Z., Shi, L., Li, A., Chen, C., & Xue, G. (2020). Retrieval practice facilitates memory updating by enhancing and differentiating medial prefrontal cortex representations. ELife, 9, e57023.
Evidence for Educators 
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