Spaced repetition: locking in what you have learned

The forgetting curve

In 1885, Hermann Ebbinghaus measured on himself how fast he forgot meaningless syllables. The result: about 70% lost within twenty-four hours, then a slower decline.

But Ebbinghaus also measured something else, and it is the real finding: each reactivation flattens the curve. After four well-spaced reactivations, loss at thirty days becomes marginal.

The principle: reactivate just before you forget

Revising too early is waste: the information is still available, so reactivation adds nothing. Revising too late means relearning everything.

The optimal window is the moment when recall becomes difficult but is still possible. That is what the research calls desirable difficulty, after Robert Bjork's work.

The Biohackademia schedule

| Reactivation | Delay | Duration |