Spacing Effect

Hermann Ebbinghaus, the German psychologist who pioneered experimental memory research, discovered the spacing effect and published his findings in his 1885 monograph Über das Gedächtnis. Using himself as the sole subject, Ebbinghaus memorized lists of nonsense syllables over varying time intervals, creating the first empirical forgetting curve. He documented that spreading repetitions over time was "decidedly more advantageous" than cramming — the first controlled comparison of the two approaches.