Spaced Repetition: The Science Behind the Most Effective Flashcard Study Method
The Forgetting Curve
Hermann Ebbinghaus mapped the forgetting curve in 1885: without review, 50% of new information is forgotten within an hour, 70% within 24 hours, 90% within a week. The decay is exponential and predictable. Spaced repetition exploits this curve by scheduling each review just as the memory is about to fade — this 'desirable difficulty' is what makes the memory stronger each time.
How Spaced Repetition Works
After correctly answering a card: next review in 1 day. Correctly again: next review in 3 days. Again: 7 days, then 14 days, then 30 days. After incorrectly answering: reset to 1-day interval. This scheduling means well-known cards appear rarely, and difficult cards appear frequently — optimal use of study time.
Active Recall: Why Retrieval Practice Works
The act of attempting to retrieve a memory — even if you fail — strengthens the memory more than re-reading. This is the testing effect (also called retrieval practice effect), one of the most replicated findings in cognitive psychology. Flashcard study is effective precisely because it forces retrieval, not recognition.
Using Study Mode Effectively
In Study mode: flip the card, attempt to answer before flipping, then mark 'got it' or 'needs review' honestly. Self-honesty is critical — marking 'got it' when you needed the answer defeats the purpose. After a session, the cards marked 'needs review' should be practiced again before closing.