How retrieval practice works part 2

In part 1 we saw how retrieval improves both the storage and retrieval strength (Bjork & Bjork, 1992) of memories using two mechanisms:

(1) Reactivation: retrieval reactivates memories speeding-up memory storage.

(2) Coactivation: retrieval coactivates related memories, changing their connectivity and clearing a path to the target.

Here’s two more potential mechanisms driving the benefit of retrieval practice:

(3) Reinstating context.

(4) Integrating memories and preserving detail.

In this blog we’ll find out about these mechanisms and what they might mean for teachers – with a brilliant strategy provided by @KristianStill.

Mechanism 3: reinstating context makes for better cues

When we form memories, they contain information about time and place, i.e. contextual features.

Imagine a pupil doing their geography homework. They are sitting in their bedroom trying to retrieve the name of the continent that Brazil is located in.

When they try to retrieve this information, they think back and reinstate the context* they studied it in, e.g., the geography lesson when/where they were taught about Brazil. Let’s call this reinstating ‘context A’.

When attempting to reinstate context A, they recall the teacher pointing at a continent below North America on the map. The pupil uses these contextual cues to recall that Brazil is in South America.

However, the pupil has retrieved this memory in a different time and place, i.e., a new context. Let’s call it ‘context B’.

When the pupil reinstates context A and retrieves the target ‘South America’, they update this memory with new contextual features from context B. These features might relate to the homework question they are trying to answer or a quick sketch they draw of South America as they try to retrieve its name.

This means the target memory is now linked to a unique set of contextual features from context A and context B combined.

Figure 1

Next time the pupil tries to retrieve what continent Brazil is in, they can use cues from context A and context B. This improves the efficiency of retrieving the target memory next time (Karpicke et al., 2014).

Compare retrieval to just re-reading information.

When we re-read, there’s no need to reinstate a previous context to remember the information… the information is there in front of us (Bai et al. 2015, Gao et al., 2016; Jonker et al., 2018). We don’t reap the benefit of updating our memories with new cues!

As with most benefits to memory, the harder we have to work, the bigger the pay off.**

Therefore, the harder pupils have to work to reinstate the previous context and retrieve the target, the greater the benefit to memory (Jonker et al., 2018; Liu et al., 2017; Liu et al., 2019).***

What might this mean for teachers?

(1) Space retrieval practice

How do we make it harder for pupils to reinstate context? (Since this will increase the benefit to memory).

We space out retrieval practice.

For example, if pupils retrieve something a while after they learned it, the context (time and place) has changed. This makes thinking back (reinstatement) harder because the context they are now in is so different.

Bingo. More benefit to memory.

(2) Use contextual cues

Whilst it is important to make reinstatement effortful, we need to balance this with pupils successfully retrieving information (Endres & Renkl, 2015).

Now we know memory is encoded with contextual features. We also know that we try to reinstate previous contexts during retrieval.

This means we can support pupils who are struggling to retrieve information by prompting them to think back or reminding them of cues from the previous learning context:

[Pupil struggling to recall the meaning of the word ‘solitude’]

Teacher: “Think back to last lesson, when we met Scrooge for the first time…

Laura made a good point about how Scrooge lives his life…”

Mechanism 4: integrating memories and preserving detail

Back to Brazil.

Imagine teaching pupils the topic “Changing Cities” in geography. First you teach them about London and then about Rio for contrast.

You want knowledge about the economy, the climate, the culture of London to connect with similar areas of knowledge about Rio. This will enable pupil to compare the two. This means you want some overlap or integration of these related memories. This forms more generalised knowledge.


It is possible for memories to become overgeneralised if they lose too much detail. Overgeneralisation here might mean pupils confuse points about London with points about Rio. Whilst the knowledge is stable, it’s not detailed enough to be helpful.

This means that ideal memories –

  • Integrate with related memories…
  • Yet helpful detail is preserved.

Integrated yet detailed… this sounds a bit like having your cake and eating it.

Luckily, with retrieval practice, we can have both! (At least at first).

Retrieving memories appears to strengthen BOTH the integration of memory with related memories AND some of the detail of the individual memory trace (Jonker et al., 2018; Lee et al., 2019; Wiklund-Hörnqvist et al., 2021; Ye et al., 2020).

This means retrieval helps to create the ideal memory for pupils (van Kesteren & Meeter, 2020).

You might (understandably) be wondering how the brain simultaneously integrates memories and strengthens distinct details.

The answer is that the brain probably stores multiple memory traces for similar information (Winocur & Moscovitch, 2011). This means an integrated memory trace and an individual memory trace can coexist (Schlichting et al., 2015).

However, this preservation of detail may not last. At first, retrieval may help strengthen integration and detail. But over time and retrievals, the detail may be lost (Ferreira et al., 2018).

What does this mean for teachers?

(1) Use multiple retrievals

To maximise the benefits of memories integrating with related memories, the neuroscientific evidence (Jonker et al., 2018; Wiklund-Hörnqvist et al., 2020; Ye et al., 2020) dovetails with evidence from psychology (Karpicke & Roediger, 2008; Vaughn & Rawson, 2011) to suggest the benefit of using multiple retrievals.

Spacing out these retrieval attempts is the best bet (Latimier et al., 2021) as we discussed above.****

But be sure to…

(2) Track the loss of memory detail

Whilst the individual memory trace might be strengthened at first, over time there may be a loss of detail. This could be problematic if important memories become overgeneralised (like the London/Rio example above).

How can we prevent this?

We can support pupils to track the loss of detail for important knowledge and restore it (van Kesteren & Meeter, 2020).

One inspired way of doing this was shared with me by school leader and English teacher Kristian Still (@KristianStill):

When giving feedback to pupils after retrieval practice, show them the perfect answer. Then they mark their work –

X for a wrong answer

for a correct but-not-perfect answer

✓ ✓ for a perfect answer that matches yours.

If it’s anything less than , pupils add the details/corrections from your perfect answer.

Kristian takes no questions about whether an answer is perfect or not: he lets pupils decide, with the guidance that, if they’re unsure, they probably should correct it.

Kristian has built this habit with his pupils. It’s improved their metacognitive awareness (an indirect benefit of retrieval practice (Roediger et al., 2011)) i.e., helping them understand what they know/do not know well.


It also helps them preserve important detail in their memories!

Now you know the four mechanisms of retrieval practice. In the next blog we’ll look at more at schemas.

*Note that ‘context’ means temporal context, i.e. it changes over time. It can be our internal context and external context (Karpicke et al., 2014).

**I’ve found only one exception to this rule so far: split attention. It’s harder to recall something if our attention is split across different tasks but this type of challenge doesn’t seem to aid memory (Gaspelin et al., 2013), perhaps unsurprisingly.

*** However, when we have learned something well, we may use context reinstatement less to remember it. The well-learned memory has been retrieved in so many contexts that aspects of the memory have consolidated into schemas to form generalised knowledge. When this happens, the contextual details of each episode become harder to retrieve. Context reinstatement isn’t necessary because the information is such an embedded and accessible part of the network anyway. This may mean context reinstatement is a time-limited mechanism of retrieval practice. Or it may be that when information is well learned, testing doesn’t produce much more benefit than restudy (i.e. there ceases to be a testing effect) in which case there are no mechanisms anymore.

**** Neuroscience research often involves using expensive equipment to scan people’s brains and so it isn’t feasible to get participants back in over and over again, i.e. to space out retrieval practice, and participants tend to retrieve the information in the scanner in one sitting (massed practice). However, it is clear that spacing retrieval practice out is better for memory.


Bai, C. H., Bridger, E. K., Zimmer, H. D., & Mecklinger, A. (2015). The beneficial effect of testing: an event-related potential study. Frontiers in behavioral neuroscience, 9, 248.

Bjork, R. A., & Bjork, E. L. (1992). A new theory of disuse and an old theory of stimulus fluctuation. From learning processes to cognitive processes: Essays in honor of William K. Estes, 2, 35-67.

Endres, T., & Renkl, A. (2015). Mechanisms behind the testing effect: an empirical investigation of retrieval practice in meaningful learning. Frontiers in psychology, 6, 1054.

Ferreira, C. S., Charest, I., & Wimber, M. (2019). Retrieval aids the creation of a generalised memory trace and strengthens episode-unique information. NeuroImage, 201, 115996.

Gao, C., Rosburg, T., Hou, M., Li, B., Xiao, X., & Guo, C. (2016). The role of retrieval mode and retrieval orientation in retrieval practice: insights from comparing recognition memory testing formats and restudying. Cognitive, Affective, & Behavioral Neuroscience, 16(6), 977-990.

Gaspelin, N., Ruthruff, E., & Pashler, H. (2013). Divided attention: An undesirable difficulty in memory retention. Memory & Cognition, 41(7), 978-988.

Jonker, T. R., Dimsdale-Zucker, H., Ritchey, M., Clarke, A., & Ranganath, C. (2018). Neural reactivation in parietal cortex enhances memory for episodically linked information. Proceedings of the National Academy of Sciences, 115(43), 11084-11089.

Karpicke, J. D., Lehman, M., & Aue, W. R. (2014). Retrieval-based learning: An episodic context account. In Psychology of learning and motivation (Vol. 61, pp. 237-284). Academic Press.

Karpicke, J. D., & Roediger, H. L. (2008). The critical importance of retrieval for learning. Science, 319(5865), 966-968.

Latimier, A., Peyre, H., & Ramus, F. (2021). A meta-analytic review of the benefit of spacing out retrieval practice episodes on retention. Educational Psychology Review, 33(3), 959-987.

Lee, H., Samide, R., Richter, F. R., & Kuhl, B. A. (2019). Decomposing parietal memory reactivation to predict consequences of remembering. Cerebral cortex, 29(8), 3305-3318.

Liu, Y., Mao, X., Peng, Y., Lu, B., & Guo, C. (2019). Dissociating neural correlates of retrieval practice and elaborative study in associative recognition memory. NeuroReport, 30(15), 985-992.

Liu, Y., Rosburg, T., Gao, C., Weber, C., & Guo, C. (2017). Differentiation of subsequent memory effects between retrieval practice and elaborative study. Biological psychology, 127, 134-147.

Roediger III, H. L., Putnam, A. L., & Smith, M. A. (2011). Ten benefits of testing and their applications to educational practice. Psychology of learning and motivation, 55, 1-36.

Schlichting, M. L., Mumford, J. A., & Preston, A. R. (2015). Learning-related representational changes reveal dissociable integration and separation signatures in the hippocampus and prefrontal cortex. Nature communications, 6(1), 1-10.

van Kesteren, M. T. R., & Meeter, M. (2020). How to optimize knowledge construction in the brain. npj Science of Learning, 5(1), 1-7.

Vaughn, K., & Rawson, K. (2011). Diagnosing Criterion-Level Effects on Memory: What Aspects of Memory Are Enhanced by Repeated Retrieval? Psychological Science, 22(9), 1127-1131.

Wiklund‐Hörnqvist, C., Stillesjö, S., Andersson, M., Jonsson, B., & Nyberg, L. (2021). Retrieval practice facilitates learning by strengthening processing in both the anterior and posterior hippocampus. Brain and behavior, 11(1), e01909.

Winocur, G., & Moscovitch, M. (2011). Memory transformation and systems consolidation. Journal of the International Neuropsychological Society, 17(5), 766-780

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.


4 responses to “How retrieval practice works part 2”

  1. […] In the next blog, we discover two more mechanisms that provide insights into how we might use retrieval practice better. […]


  2. […] Sarah Cottingham continues her exploration of how retrieval practice works with part 2. […]


  3. […] strength. Ze beschrijft in haar blog twee mechanismes met daarbij wat die voor de docent betekenen. In haar tweede blog komen nog twee mechanismes aan […]


  4. […] the cues given) over time (whilst still balancing this effort with ensuring a decent success rate). The second talks about how we can use contextual cues to activate schemas for successful retrieval (again […]


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