Spaced repetition is a learning technique that shows you information at increasing intervals based on how well you know it. Cards you struggle with appear more often. Cards you know well appear less. The result: you study less but remember more. It's backed by over 100 years of cognitive science research, starting with Hermann Ebbinghaus in 1885.
In 1885, German psychologist Hermann Ebbinghaus discovered that memory decays exponentially over time. Within 24 hours of learning something new, you forget roughly 70% of it. Within a week, you've lost over 90%. This is called the forgetting curve.
But Ebbinghaus also discovered something else: each time you review the information, the forgetting curve flattens. The memory becomes more durable. After 4-5 well-timed reviews, the information moves from short-term to long-term memory, where it can last months or years.
You study a piece of information — a vocabulary word, a medical term, a historical date, a programming concept. This is your first exposure.
The algorithm shows you the information again just before your memory of it fades. This is the "spacing effect" — reviewing at the optimal moment maximizes retention with minimum effort.
Each successful review increases the interval. First review after 1 day, then 3 days, then 7 days, then 21 days, then 2 months. The schedule adapts to each individual card based on your performance.
If you forget a card, the interval resets and it appears more frequently. Easy cards fade into longer intervals. Your study time automatically focuses on what you need most.
Spaced repetition exploits two cognitive phenomena:
Distributing practice over time produces better long-term retention than cramming the same amount of practice into a single session. Studying 10 minutes a day for 6 days beats studying 60 minutes in one sitting. This is one of the most replicated findings in cognitive psychology.
Trying to retrieve information from memory strengthens the memory itself. Reading your notes is passive. Looking at a question and trying to recall the answer before checking is active. Flashcards force active recall on every single review, which is why they outperform highlighting, re-reading, and summarizing.
Over 86% of medical students use Anki for board exam preparation. USMLE, MCAT, pharmacology — the volume of material is so large that spaced repetition is the only practical way to retain it all.
Vocabulary acquisition is the classic use case for spaced repetition. Learning 20 new words a day is manageable when the algorithm handles the review schedule. Without it, vocabulary fades within weeks.
Case law, statutes, constitutional amendments — law requires memorizing vast amounts of structured information. Spaced repetition is increasingly popular for bar exam preparation.
The latest advancement in spaced repetition is FSRS v6 (Free Spaced Repetition Scheduler), which models your individual forgetting curve using machine learning. It reduces reviews by up to 30% compared to older algorithms like SM-2. Forgetless uses FSRS v6 as its built-in scheduling engine — the same algorithm available in Anki via plugin, but with zero configuration required.
Create your first flashcard deck with AI. FSRS v6 handles the scheduling. No credit card required.
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