The forgetting curve

More than half, within an hour

Key ideaWe forget fastest in the first few hours

In 1885, the German psychologist Hermann Ebbinghaus memorized lists of nonsense syllables, waited, and then learned them again. The white dots show how much time he saved the second time. After 20 minutes he saved 58%, after an hour 44%, and after a day only 34%. Forgetting is fastest in the first few hours, then it slows down.

Why?He used nonsense syllables so that nothing he already knew could help. The less time he saved, the more he had forgotten. This shape, steep at first and flat later, has turned up again and again in later studies. In 2015 a team in the Netherlands repeated the experiment and got almost the same curve.

Go furtherThe bottom axis is not evenly spaced. To fit one minute and one month on one screen, time stretches more and more as you go right. Only the white dots were measured; the line just joins them. Even after a month he still saved 21%. Something stays, even when it feels completely gone. This is called the forgetting curve.