1850–1909 · psychologist, Berlin, Breslau, Halle

bbinghaus brought the experiment to memory, a subject many thought too inward to measure. He was his own and only participant, and his short book (Ebbinghaus, 1885) is still read for its method as much as its results.

what he did

To strip meaning out of the material, he learned lists of nonsense syllables, consonant–vowel–consonant, read aloud at a fixed, steady pace. He measured memory by savings: how much less work it took to relearn a list to the point of one error-free recitation than it had taken the first time. Relearning at intervals from about twenty minutes to a month gave the forgetting curve: fast loss at first, slower later. He also found that repetitions spread over days did more than the same number crammed into one sitting.

In his words (from the 1913 English translation, chapter 7): "One hour after the end of the learning, the forgetting had already progressed so far that one half the amount of the original work had to be expended before the series could be reproduced again; after 8 hours the work to be made up amounted to two thirds of the first effort." More is in the reading room, on forgetting.

what held up

A great deal. Murre & Dros (2015) repeated the experiment with one participant over seventy hours of learning and relearning, and got a curve very like his, with one wrinkle: a small upward jump at the one-day point. The Ebbinghaus illusion, a circle that looks larger among small circles, also carries his name.

in the tour: the first laboratories have "Ebbinghaus, nonsense, 1885" and "Savings, and the curve" ···

Primary works and sources

1. Ebbinghaus (1885). Über das Gedächtnis. Leipzig: Duncker & Humblot. English translation by H. A. Ruger & C. E. Bussenius, Memory: A Contribution to Experimental Psychology, Teachers College, Columbia University, 1913; transcribed at Classics in the History of Psychology. psychclassics.yorku.ca/Ebbinghaus/index.htm
2. Murre & Dros (2015). Replication and Analysis of Ebbinghaus’ Forgetting Curve. PLOS ONE. doi:10.1371/journal.pone.0120644

see also

	forgetting — the reading room, in his own words
	replication — a result that did replicate
	savings — the measure he invented