Spaced Repetition: The Science of Remembering More With Less Effort
The Forgetting Curve
German psychologist Hermann Ebbinghaus identified in the 1880s that memory decays rapidly after learning. Without review, you forget roughly 50% of new information within 24 hours and up to 90% within a week.
The good news: reviewing information at the right moments resets the curve and dramatically slows forgetting over time.
What Is Spaced Repetition?
Spaced repetition is a revision schedule in which you review material at increasing intervals. Instead of reviewing everything every day, you review each piece of information just before you are likely to forget it.
A typical schedule for new material:
- Review after 1 day
- Review after 3 days
- Review after 7 days
- Review after 14 days
- Review after 30 days
After five or six spaced repetitions, most information is effectively in long-term memory.
How to Apply It Without an App
You do not need software to use spaced repetition. A simple approach:
- Write new topics on index cards when you first learn them
- Place them in a box divided into sections: 1 day, 3 days, 1 week, 2 weeks, 1 month
- When you review a card correctly, move it to the next section
- When you get it wrong, return it to the 1-day section
How to Apply It With an App
Anki is free, cross-platform, and widely used by medical students and language learners. You create flashcard decks and Anki automatically schedules each card based on how confidently you recalled it.
Combine With Active Recall
Spaced repetition tells you when to review. Active recall tells you how to review. Together, they are the most time-efficient revision system available.