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The importance of spaced review



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The importance of spaced review

You’ve experienced spaced review. I promise. Think back to the last time you tried to teach somebody something. Anything. Whether that was your child being potty trained, or teaching your colleague how to be potty trained. Did your learner completely understand your content and become an expert immediately?
(Those of you that are thinking of the dreaded potty training process are probably screaming “no!” at your screen right now)
Well, that’s because to learn, we need to recap the topic time and time again. This is known as ‘spaced practice’. We need this to effectively learn anything.


The forgetting curve

Hermann Ebbinghaus’ ‘forgetting curve’ depicts the importance of spaced practice in learning. Ebbinghaus was a German psychologist who pioneered the experimental study of memory.
Ebbinghaus conducted his research with chunks of nonsense letters, like CFQ or DTV. He memorised them and then noted how much he was able to remember after the passage of set periods of time. This research ultimately showed how learners forgot information over time, if there was no attempt to retain it.
Learners forget up to 50% of information within an hour. So it is unsurprising that as learning designers, we want to devise strategies to mitigate this loss of knowledge. These strategies usually fall to spaced review. Repeating our learners exposure to information over differing time periods, so it becomes fixed in their long-term memory.
A familiar approach to training has long been, tell them what you are going to teach them, tell them and tell them what you just told them.
And to some extent, we can see by the learning curve that this will work, especially if there is a bit of a gap between each repetition.

The impact of spaced review

The forgetting curve

As you can see from the above graph, if we don’t refresh what we learn, we forget it – rapidly. But it also shows how retention increases with each learning event. The more learners refresh their understanding of the information, the longer they will retain the knowledge. With spaced review, the forgetting curve becomes flatter, and each time you refresh the information the rate of loss decreases.
Memory improvement techniques show that refreshing memory at lengthening intervals improves memory retention. If we refresh ‘chunks’ of memory by recalling them at increasingly longer intervals we make that memory really long-lasting.
This makes the neural pathway stronger, as the neurons go back and forth at increasing intervals.

Increasing knowledge retention: A neurological change

 We’ve all seen scenes like this:


A man made path
People (literally) cutting corners across a grassed area, rather than walking around it. Over time, the grass dies, and a ‘man-made’ path forms.
The day after someone took this shortcut for the first time, there would not be much trace of their passing. After a week of one person walking the same route, the grass would be a bit flattened and someone else might notice the route and follow it. As more and more people use the route, the stronger and more permanent it becomes.

This is exactly how memory works.

To turn short-term memories into long-term ones, our brains must define, the information and decide where to store it. If we have any memories to which it can be related, a neural pathway is created between them.
Every time you activate and review the new information the memory traces become stronger. Every time you link that memory with another memory, the memory traces become stronger.
Long-term memory retrieval requires revisiting the neural pathways the brain formed. The strength of those pathways determines how quickly you recall the memory. To reinforce that initial memory, it must move multiple times across the nerve cells, retracing its steps.

The stronger the memory, the longer and more readily you are able to recall the information.

Due to this this, the learning curve becomes flatter. You retain information for longer, and the interval over which you need to review and refresh it becomes longer.
Parents who have read the same book, every night for months, to a young child will have experienced this phenomenon. For example, my dad can recite the entire story of ‘Andrew’s Engine’ off-by-heart 35 years after he first read it to my brother. (Much to his grandchildren’s delight and amazement!) He never set out to learn this book. But it was well and truly embedded all the same.
You will no doubt have lots of similar, really solid memories that don’t even feel like memories, they are so automatic. They’re not things you remember, they are things that you know.

What does this tell us about how we can retain the things we are trying to learn?

By looking at the learning curve, we can see that frequent spaced review can help retention, but over time, we still tend to forget what we’ve learned.
Some memory experts claim retention can be increased depending on how the information is presented to learners.
The Fuzzy Trace Theory states that we remember things in two ways: verbatim and gist. When we remember ‘the gist’ of things, we remember the most important piece of information about a topic, without details. When we remember things ‘verbatim’ we remember every detail.
Let’s use an example close to my heart. If a bar worker needs to learn about a new craft gin. The gist would be ‘gin, alcohol, spirit’. The verbatim memory would be more like: Pollination Gin, award winning, made in Corris, the glass to be used, and types of tonic that go well with it.
The more we can help the learner to register both the gist and the verbatim information clearly – the better we can help to prepare them to store it.

What techniques can we use to help with retention?

Link to pre-existing knowledge

Is there any way in which we can flag up the link between the new information and any existing knowledge that the learner may already have? Can we help them to use memory hooks / mnemonic devices to represent the new information in a way that links it to already familiar concepts?
The more relevant, meaningful connections you can make with the new information in your mind with things you already know, the better your memory retention over time.
Why does it matter?
Can we help the learner to regard the information as important to them? Attaching higher importance to information makes it more likely to be remembered. If you learn something, and it is important to you, and you can connect it with many things you already know, your memory retention will be very high.
How lengthy and complex is the information?
Can the information be simplified? Chunking information into concise related information makes the retrieval easier. Ebbinghaus remembered random letters in groups of threes rather than in long strings.

Spaced practice

If a learner doesn’t believe that the learning doesn’t relate to anything they already know, then repetition is a good strategy. Reviewing the information frequently at first, and then at regular intervals will give the best outcome.
When learners revisit learning at their regular, spaced intervals, the brain needs to be actively engaged. This is why question practice is so effective, as the brain is actively engaged in seeking to retrieve the original information.
Think of the mental processes involved in reciting your four times table, that you learnt in primary school. Many readers, especially those educated in Britain, are probably reciting ‘one times four is four, two times for is eight’ at the sheer memory of it. This is habitual and practised. But if I asked you what four times twelve is, I’m sure it’ll take you a while to get there.
In the first instance, I’m asking you to retrieve information from a strong neural pathway. The second, isn’t so strong – but you could probably get there if you said ‘four times twelve is… forty-eight’ just as we would have in school.
So there you have it, the forgetting curve, knowledge retention and spaced review explained! If you have any questions, or need help with your digital learning development, get in touch, we’d love to help!
Editors note: This blog was first published in January 2019. It has been updated for clarity, with fresh new content included.