By Nikita Choudhary


This blog is all about retrieval and spacingwhich are techniques that I have been using for the last two years or so in education. Retrieval practice is all about actively bringing information to mind without looking at any materials. Spacing is distributing study sessions over a period of time, as opposed to ‘massing,’ which involves arranging such sessions closely together (Weinstein et al, 2018).  

I am a graduate in Biological Sciences and I am currently in my third year of studying Medicine. When I began the latter, I realised that for most of my educational life, I was a rote learner and my goal was always to study for the examBut I wanted to shift my focus to truly understanding and applying the principles of my course to my practice for the long term. As a resultI started exploring retrieval and spaced practice and I can safely say that these strategies have transformed my learning journey. 

In this blog, I will provide aaccount of the research behind retrieval and spaced practice and why they enhance learning. In so doing, I will share a small glimpse of my thoughts and experience as a student, which may hopefully encourage others to engage in such techniques as well. 

Retrieval Practice

Many years of research has demonstrated that retrieval practice is more effective than re-studying informationAn important experiment that marked the beginning of such research involved a group of students re-reading a science text versus doing a free recall test, whereby in the latter they had to write down everything from memory. When they were re-tested after a week, the free recall group performed better, despite having less exposure to the material (Roediger & Karpicke, 2006). 

Another important study that examined retrieval practice was conducted by Larsen (2009), in which residents learnt about myasthenia gravis and status epilepticus. After having attended a teaching session, one group took a short-answer test, whereas the other revised a study sheet. They received an opportunity to take the test/study the material again two weeks later. Finally, they were examined six months later and they observed that those who engaged in retrieval practice outperformed those who simply restudied. An additional finding was that the majority of residents felt more inclined to using regular tests as a means of improving their long-term memory. It has even been shown that retrieval practice is not confined to revising such factual information; it can improve spatial relationships and procedural skills, too (Larsen, 2018).  

Retrieval practice has been compared to the methods of elaborative studying like concept mappingwhich involves visual representations of information and drawing links between ideas within an established framework of the topicSo, Karpicke and Blunt (2011) ran a study in which undergraduate students attended a study session initially, then one group designed a concept map with the materials in front, whereas the other group studied by engaging in recallResults showed that retrieval practice produced better learning in the final test questions conducted later. Furthermore, to ensure that the results were truly down to retrieval practice, rather than from the bias that the final test potentially mimicked retrieval practice conditions, they changed the testing format from questions to creating a concept map. Following this change, they still demonstrated that retrieval practice was more effective than elaborative studying via concept mapping. 

When reading this paper, I thought why not generate concept maps without looking at thmaterial, which would then incorporate retrieval practice? Indeed, researchers discuss this as an option that can be used to make the learning process more active. However, considering that a lot of students still engage in using a pre-existing structure and subsequently make richer connections through concept maps (as opposed to true retrieval), the study focused on comparing these strategies individually to emphasise that the fundamental mechanisms of these strategies differ and that retrieval is more effective. 

What is the underlying mechanism though that governs retrieval practice? Why does it workIt is proposed that retrieval practice has a strong relationship with consolidation, the basic mechanism of memory formation. Consolidation involves a dynamic interplay between the cortex and the hippocampus in our brain. The memory is reconstructed and reorganised constantly overtime and retrieval is said to speed up this process. Repeated attempts of retrieval i.e. reconsolidation strengthen the neural connections and thus, memory (Larsen, 2018). 

Now let us shift the discussion towards spaced practice. Although I am referring to retrieval and spaced practice as two separate entities, in reality they are interlinked and should follow on from each other. In order to explain this, I would like to refer to the term ‘storage strength’ used by researchers Bjork and Bjork (1992) to help explain this connection. Storage strength – as the name suggests is the extent to which information is embedded within memory. The researchers discuss how retrieval strength and storage strength share an inverse relationship; the more easily you can access memories in that given moment, the smaller the advances in retaining those memories. They explain that if we perceive how easily we retrieve memories in the given moment as a reflection of our storage strength, then we reduce the quality of our learning. The goal is to create ‘desirable difficulties’ that specifically lower retrieval strength through techniques like spaced repetition. It is important to note that retrieval, in itself already brings in this element of challenge into the learning process but what will add to this is the creation of intervals between study periods. We need to allow forgetting to ultimately enable the long-term retention of information. A more relatable and perhaps familiar way of putting this is the harder you make something to learn, the more likely you are to remember it for longer. So, what is the research behind spacing? 

Spaced Practice

Spacing, also known as distributed practice was first introduced in the 19th century by researcher Ebbinghaus who concluded that this revision technique is better than massing or cramming (Weinstein et al, 2018; Ebbinghaus, 2013).  

Several studies since have demonstrated the benefits of spaced practice: Bloom and Shuell (1981) conducted a study involving two groups of high school students.  One group memorised French-English vocabulary pairs over thirty minutes in one day versus the other group that memorised the same pairs but in bursts of ten minutes spread over three days. They found that when tested seven days later, performance was better in the second group. 

Researchers Rawson and Kintsch (2005) showed that spacing is also effective when learning prose; again, a massed group and a distributed group were given an article to read from a scientific journal that was broken down into sections. Each section was introduced to the students step-by-step, whereby the massed group could revisit the same article immediately, whereas the distributed group were instructed to do the same a week later. This study specifically investigated short-term and long-term performance in more detail, using the phrases ‘immediate testing’ versus ‘delayed testing’ instead. Upon immediate testing, they discovered that the massed practice group performed at a significantly better level and the reverse was true upon delayed testing. These results were replicated in previous studies conducted by researchers like Glover and Corkill (1987) and Krug et al (1990) (cited Larsen, 2018)Thus, the results depict the reality of how cramming works for the immediate exam, but not for the delayed exam.  

Taking you back to Rawson and Kintsch’s (2005) study, they used the method of re-reading, but as seen in the previous section, retrieval practice has been shown as a more effective strategy. Indeed, in this paper the researchers acknowledge that it is the advent of active methods like retrieval (compared to passive strategies like re-reading) that will allow further gains in learning.  

We have discussed how spacing creates a desirable difficulty in retrieval practice. To further expand on why it enhances learning, it has been suggested that ‘contextual-fluctuation models’ are involved (Mensink Raaijmakers, 1988): when we cram the night before the exam, our standard of performance is high the next day due to the cues that are fresh in our memory. However, this information is forgotten rapidly because the cues evolve over a period of time. When we engage in spaced practice, we then allow ourselves to become exposed to a wider range of cues associated with a particular topic and although performance may show a steady climb, storage strength i.e. learning, nevertheless becomes stronger (Soderstrom & Bjork, 2015).  

Often, students prefer to review crucial information sooner rather than later because they fear too much information may have been forgotten. Subsequently, study sessions are no longer spaced and students no longer reap the benefits from them (Bjork Bjork, 2011). Thus, a question that may arise amongst students is if we were to engage in spacing, how do we determine the appropriate intervals between study sessions?  

Several studies have suggested the approach of expanding retrieval intervals (Kuepper-Tetzel et al., 2014; Toppino et al., 2018). What this means is that initially, study sessions can be placed closely together, but as time progresses, the intervals can be increased. In this way, you are striking a balance between establishing a basic foundation of learning and allowing some level of effortful learning.  

This, in fact is a point at which I would like to bring in my own experience as a learner. I completely understand the sentiment of students who fear the idea of inappropriately spacing to the point that they must relearn the material. It is because of this very fear that I engaged in expanding intervals as a form of spaced practice. For example, during my pre-clinical years, once I had revised the material that was covered on the same day, I would arrange my first retrieval study session the next day, three days, a week and subsequently three weeks later. In so doing, this would allow me to engage enough with the material in the initial study session and as a result, establish a foundation to work from in subsequent sessions that have much longer intervals between them. 


When I sat down to the write this blog post, my aim was to share the basics of these techniques and provide a summary of some of the key researchAnd it is clear that retrieval and spaced practice are emerging keystone techniques of long-term learning. However, what struck me is that as conceptsretrieval and spacing are actually logical or intuitive and may even be something that some students practise already but they do not consciously define them. It makes perfect sense that reviewing material repeatedly will cement knowledge for longer. Furthermore, as mentioned we know from human experience (and now from research that has been mentioned above) that cramming the night before an exam may guarantee us short-term success but definitely not long-term success 

Thus, what is it about spaced practice that is new? To answer this question, I pose another question: Do we really know the most effective way of doing it? Suppose you are someone who already conducts spaced practice, what is the frequency of those spacing sessions? If we shift our attention towards retrieval practice: When you sit down to review your material, do you actually engage in the activity of drawing out information from your own head or do you re-read notes – which does not engage in retrieval at all and instead gives a false sense of knowing the content when most likely you do not? Suppose you do engage in retrieval practice, how long do you spend doing this before you give in and fall back to your notes?  

The take-home message in all that I explain is that the way you practise these techniques is important. More specifically, what matters is whether an element of challenge is being brought in.  

This is especially hard to follow because subconsciously we probably feel that learning should be easy. But I think this specifically applies to the situation in which we learn a concept in its infancythe aim should be to try and capture the essence of what is being learnt to the point that we can take pages and pages of information and boil it down to just a few.  

But there is a part of learning that needs to be effortful, which I believe occurs primarily during the review process and it is achieved through strategies like retrieval and spaced practice. This idea of effortful is something students are perhaps not so well-versed or even comfortable with. But the fundamental reason it is important is that it guarantees longer term retention of information and makes the recall of ideas from memory relatively easier. I have certainly seen the change in my own journey and would urge students to make this subtle shift in their own learning, too. 

About the Blog Post Author:

Nikita Choudhary is a graduate in Biological Sciences and she is currently a 3rd year medical student at the University of Leicester. At the start of her second degree, Nikita reflected on her learning journey and realised that she had fell into the trap of “rote-learning.” Since then, she decided to research about effective learning by exploring a range of articles, videos and podcasts from which she discovered the techniques of retrieval practice and spaced repetition. In particular, she also utilised resources provided by the Learning Scientists that helped her greatly in implementing these learning strategies into her study routine. Nikita is delighted to be a part of the Student Voice within the TILE Network and would like to use this platform as an opportunity to spread the word about how retrieval practice and spaced repetition, amongst the many other strategies can transform one’s learning experience. You can follow her on Twitter: @NikiNak16 

TILE Student Voice

This is a new section of the TILE Network that features the student voice in learning and teaching. We want to shine a light on the student perspective when it comes to teaching and learning practice and what better way to do this than letting the students express this themselves. This series also aims to give students to opportunity to engage in science communication and writing. Broadcasting scientific findings to a wider audience is a valuable skill and TILE provides students with the platform to practice that skill.

If you are a student and interested in contributing to the TILE Student Voice section, get in touch:


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