What is spaced repetition in learning?

The goal of training is getting learners to remember and apply the new information and skills they learn. Simply exposing learners to that information is not enough to ensure that they remember it, though. 

What research shows is that learners must be exposed several times to the same information, ideally with time gaps between exposures — spaced repetition — to successfully build long-term knowledge retention that undergirds successful learning.

Forgetting aids remembering

In the 1880s, a German psychologist by the name of Hermann Ebbinghaus was studying memory. Testing himself, he performed a series of experiments on how long he could remember lists of nonsense words.

Ebbinghaus is remembered primarily for the concept of the “forgetting curve,” which arose from that research. He found that learners will forget up to half of what they’ve just learned within one hour of completing training. After a week, they’re likely to have forgotten nearly everything!

This forgetting of most information is essential; the sheer amount of information the average human encounters in a day or a lifetime is immense, and no one could possibly need or want to remember it all.

Researcher Benjamin C. Storm found that “it appears that thinking and remembering rely at least in part on a process that underlies forgetting” — and that’s partly because recalling salient information can only happen if recall of other, unimportant, information doesn’t “interfere.”

Storm also found that “retrieval practice causes the retrieval-induced forgetting of non-practiced exemplars.” The brain focuses on remembering the material that is repeated or that the learner is asked to use — and forgets information that is not repeated.  

Repetition makes learning stick

To remember information over the long term, then, a learner must be exposed to that information multiple times and repeatedly practice recalling or retrieving that information.

Because of the way humans’ memories work, information that is encountered multiple times is more likely to be fixed into long-term memory. Information that is encountered only once is discounted as unimportant; it thus never moves from short-term recall into long-term memory.

That’s why exposing learners to important training content multiple times improves their retention. It’s even better to ask learners to recall or use information in different ways. In different repetitions, a learner might be asked to define a term, retrieve it in a matching or fill-in-the-blank activity, or explain how they would use the concept in various work-related scenarios. This enhances long-term retention by helping the brain build connections between related bits of information.

Researchers Diane Halpern and Milton Hakel call this type of “practice at retrieval” the “single most important variable in promoting long-term retention and transfer.”

Spaced repetition is most effective

Multiple studies have found that repetition of content with breaks is a highly effective way to build retention. Learners who study in short sessions, with breaks of varying lengths, outperform those who study in a single long “massed learning” session. This is true whether the learners are exposed to new material or the spaced repetition reviews material they have learned more conventionally, in a lecture or eLearning course, for example.

Tabibian et al. found that ability to remember a piece of information depends on three factors:

• The number of times a learner reviews it
• The “temporal distribution” or  length of time the learner is exposed to repetitions
• The amount of time that has elapsed since the last repetition

When information is new, repetitions should be closer together; as memory becomes stronger, the repetitions can be spaced farther apart.

According to Make It Stick, each spaced-apart attempt to recall information reminds the brain that the information is important and renews the “consolidation process” of connecting that information with other information, making sense of it, and storing it in long-term memory. And the harder it is to recall the information — by spacing out learners’ efforts to remember it and by asking them to recall and use it in different ways — the stronger the learner’s retention becomes.

Microlearning is ideally suited for spaced repetition in learning

Whether learners need to recall, practice, and retain information they’ve learned in a comprehensive eLearning course or a 3-day workshop or they need to learn and remember new information, microlearning is a great tool for spaced repetition.

Microlearning is generally mobile-friendly and available on demand, and each lesson is short. These characteristics increase the odds that learners will actually complete the repetitions.

Many microlearning platforms can deliver content automatically, on a “drip delivery” or everboarding paradigm that conditions learners to spend a few minutes every day or several times per week learning. Those sessions provide ample opportunities for spaced repetition. And using an adaptive learning algorithm ensures that each learner gets the content they need most on the schedule that optimizes their recall practice — and maximizes long-term retention.

Build long-term retention

Make learning stick and build long-term retention with spaced repetition. Add a continuous microlearning knowledge retention campaign to your existing training — or teach new information using this proven paradigm. Either way, spaced repetition is a great way to improve the effectiveness and impact of your training.

For a deeper exploration of this and related topics, download the Cognitive Science behind OttoLearn whitepaper.