Ebbinghaus Forgetting Curve
The mathematical model showing how newly learned information is rapidly lost over time when no attempt is made to retain it.
An empirical exponential decay model describing the decline of memory retention over time, characterized by steep initial loss within the first 24 hours followed by a leveling off as memory traces consolidate or decay.
Historical & Empirical Context
Discovered in 1885 by German psychologist Hermann Ebbinghaus through pioneering self-experimentation with nonsense syllables, establishing the quantitative study of human memory.
Core Principles & Mechanics
Without review, humans lose up to 50% of newly memorized material within 1 hour and up to 70% within 24 hours.
Each properly timed review resets retrievability to ~100% while reducing the subsequent slope of decay (increasing Stability S).
In Practice
Ebbinghaus measured the problem; modern schedulers sell the solution β you no longer need to guess when to review.
Treat the curve as a budget: without reviews, ~70% of today's vocabulary is gone within a week.
Each successful review flattens your personal curve β the app's growing intervals are evidence, not app enthusiasm.
Don't cram before 'forgetting': reviewing at high retrievability wastes time you could spend on new cards.
After a long break, expect the curve to reset steeper β schedule shorter intervals again rather than trusting old stability.
Classical exponential retention formula where R is retrievability, t is time elapsed, and S is the memory stability constant.
Frequently Asked Questions
How do you beat the Forgetting Curve?
By using an adaptive Spaced Repetition algorithm (like FSRS-5) that schedules reviews at the precise moment retrievability drops to 90%, maximizing memory consolidation with minimal repetitions.
Related Glossary Concepts
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