Spaced repetition, also known as spaced practice or distributed learning, is one of the most effective strategies to learn deeply and effectively. Essentially, spaced repetition spreads out learning over time, as opposed to compressing or cramming learning into a single session. Spaced repetition and microlearning principles align because they allow you to space out brief learning sessions over time.
Across the board, studies show that spaced repetition is more effective than cramming in measuring long-term knowledge retention. A learner who separates learning sessions by as little as one day improves retention, compared to a single learning session. Distributing learning sessions over weeks or months benefits long-term retention even more, even without spending more hours than one spent cramming.
Here’s what not to do:
Take a look at the graph below, based on the Ebbinghaus Forgetting Curve. Knowledge retention slowly decreases over time. But note: with each successive repetition, the decrease in retention gets smaller.
And that’s why continual learning through spaced repetition matters: by repeating learning experiences over time, people gradually remember more and more until the information is memorized.
Image source: Schimanke, Mertens, and Vornberger
And for more proof, a 2006 meta analysis by Cepeda et al. collected data from 184 articles and 317 experiments. Their analysis showed an average observed benefit of 15% on verbal recall exercises when comparing people completing spaced study to a ‘crammed’ practice program.
Spaced repetition has shown benefits across a wide range of groups: adults and children, cognitive and physical tasks, and low and highly complex tasks. Let’s look at an example of spaced repetition in a high-complexity environment.
A 2010 study by Arthur et al. investigated a complex command-and-control warfare task for participants acting as a naval commander. In the experiment, one group trained for 10 hours across a 2 week span; the other group concentrated 10 hours of training within a single week. The first group ended up faring significantly better than the second because they spaced out their learning over longer (although it wasn’t more time in aggregate). The longer spacing strategy showed improved task performance and long-term retention over a variety of tests and recall periods.
Spaced repetition is effective beyond studying for a test: it’s applicable across different scenarios across different types of organizations, including high-stakes, high intensity environments.
Research findings could impact a wide range of fields where employees “receive an initial training on skills or knowledge that they may not be required to use or may not have the opportunity to perform for extended periods of time,” according to Arthur.
Rather than a single annual training session, companies should host shorter sessions spread out over the course of the year. Football programs shouldn’t expect their players to remember every concept from preseason installs: instead, they should review key concepts weekly and quiz regularly to improve long-term retention.
And beyond just increasing knowledge retention, spaced repetition increases the depth of learning, helping learners move beyond just recall and to more advanced actions such as applying and analyzing.