Spaced repetition: come back just before you forget

Spreading practice over time beats the same amount of practice in one block, and the best gap grows with how long you want to remember.

The evidence

Cepeda, Pashler, Vul, Wixted & Rohrer (2006), Distributed practice in verbal recall tasks, Psychological Bulletin 132, 354–380 pooled hundreds of experiments: spaced practice produced better long-term retention than massed practice.

Cepeda, Vul, Rohrer, Wixted & Pashler (2008), Spacing Effects in Learning, Psychological Science 19, 1095–1102 asked what the gap should be. The best gap grew with the delay before the test. As a share of that delay, it fell from about 20–40% for a test a week away to about 5–10% for a test a year away. For durable knowledge, that means reviews weeks and then months apart.

How to do it

1. Review with retrieval, not re-reading (see retrieval practice).
2. Let a scheduler pick the dates. FSRS, the open-source spaced-repetition scheduler models your own forgetting curve and schedules each item just before you're likely to forget it.
3. Keep review items small and precise: one idea per question.
4. Don't count something as learned until it survives a review days later.

Sources

• Cepeda, Pashler, Vul, Wixted & Rohrer (2006), Distributed practice in verbal recall tasks, Psychological Bulletin 132, 354–380
• Cepeda, Vul, Rohrer, Wixted & Pashler (2008), Spacing Effects in Learning, Psychological Science 19, 1095–1102
• Dunlosky, Rawson, Marsh, Nathan & Willingham (2013), Improving Students' Learning With Effective Learning Techniques, Psychological Science in the Public Interest 14, 4–58