📉Forgetting curve

Memory for something newly learned drops steeply at first and then levels off. Hermann Ebbinghaus measured it on himself in the 1880s with lists of nonsense syllables, using what he called savings: how much less time it took to relearn a list than to learn it the first time. The report is 🔬 Memory - A Contribution to Experimental Psychology.

What spacing does to it. Each review lifts retention back up, and the decline after it is gentler than the one before. Reviews spread over days beat the same minutes spent in one sitting. The cheap moment is just after the steep part, before the thing has to be learned again from nothing.

Example: lecture notes. By Friday I could reproduce perhaps three points of Tuesday's lecture. From 28 April I went back to each set on a schedule, for the six weeks before the final, which is 🧪 Spaced review of lecture notes.

Often confused with: the learning curve, which is about getting faster with practice. Also with a law: his syllables were meaningless on purpose, so his curve is close to the worst case.

• Notes: 📖 Ebbinghaus on forgetting
• Claim: 💎 Forgetting is fastest right after learning
• The tidy later equation: 📐 Retention after t days
• Where I first met spacing: 00. Learning How to Learn Hub