Spaced Repetition

Spaced repetition = testing + time

Everything you learn starts decaying straight away. Hermann Ebbinghaus measured it in the 1880s: the forgetting curve drops steeply at first and then flattens. Each time you successfully recall something, the curve resets and gets flatter. The memory lasts longer before it fades again.

The method

1. Test yourself. Actively recall the answer rather than re-reading it. Retrieval is what strengthens memory.
2. Space it out. Review just before you’d forget, so each success lets the next interval grow: a day, three days, a week, a month.
3. Reset on failure. Forgot it? Back to a short interval.

Repeat a word all day and you’ll know it tonight and lose it in a few months. See it every few days, then every few weeks, and you’ll still know it in a year, with far less total effort.

Not everything decays at the same rate

Different material has different curves, and they’re personal. I remember numbers easily and song lyrics badly, so lyrics need more frequent reviews. Good spaced-repetition tools adapt the interval to how hard you found each recall.

Why it feels odd

It’s a strange habit to build. It feels slower than reading a chapter again, and it’s uncomfortable to fail a recall. Both are signs it’s working: effortful retrieval is the point.

Beyond flashcards

The same principle works on notes, not just facts. In my own system, every knowledge note carries a next-review date. When I review a note and it still holds up, the interval grows; when it doesn’t, it shrinks and I rewrite it. That turns my notes into something closer to a flashcard deck for ideas. It’s the “Discover” step of LOGREDIS, and it’s how seeds in this garden grow into evergreens.

A training parallel

Skill training works the same way. You don’t learn a handstand by practising for six hours once; you learn it in short, frequent sessions spread over months. Spacing beats volume, in the gym and in the head. (Attention is the other half of the problem: Learning When Everything Wants Your Attention.) Related: Comprehension Requires Your Own Words, because you can only recall what you understood in the first place.