What is spaced repetition and how does it work

Spaced repetition is a memorization method where you review material not back to back but at intervals spread out in time, and each review increases the optimal interval before the next one.

Where the method comes from

In 1885 the German psychologist Hermann Ebbinghaus published his study of memory, which gave us the forgetting curve: without reviews, memory of new knowledge roughly halves within days or weeks. His premise became the core of the method: after each review, the next one can be pushed further away.

The effect has been tested many times since. A 2006 meta-analysis by Cepeda and colleagues collected a large body of experiments on distributed practice: reviews spread out in time consistently beat cramming across very different materials.

Why it works

Expanding intervals are believed to work because retrieval gets harder: the more time has passed since the previous review, the more effort it takes to pull the information out of memory — and that effort is what memory benefits from.

The second ingredient is active recall. In the experiments of Roediger and Karpicke, students who answered questions about the material remembered noticeably more a week later than those who spent the same time rereading it.

How it works in Revomia

In Revomia, cards are grouped into topics, and each topic has a review rule — a sequence of pauses in days. After each review the card moves to the next pause; once the pauses run out, the card counts as learned.

The date of the next review is counted from the moment you actually reviewed the card, not from a missed deadline. So a postponed review does not snowball the queue.

The “easy” and “hard” ratings you give while studying go into statistics, while the schedule is driven by the topic rule — the review timetable stays predictable.

How to start

Create a topic, add cards by hand or let AI generate them from your own text — and in language topics from a photo of your notes as well. Then work through the deck on the study page. Reviews spread out in time build stronger memory than the same amount of repetition in one sitting.