Hermann Ebbinghaus

Who was Hermann Ebbinghaus?

Hermann Ebbinghaus was a German psychologist and philosopher who lived from 1850 to 1909 and taught at the universities of Berlin, Breslau and Halle.^[1][2] Born in Barmen, now part of Wuppertal, he studied history, philology and philosophy at Bonn, Halle and Berlin, served in the Franco-Prussian War of 1870–71, and earned a doctorate at Bonn in 1873 with a thesis on Eduard von Hartmann's philosophy of the unconscious.^[1][2]

He then spent about seven years studying on his own, partly in England and France.^[2][3] During that time he read Gustav Fechner's Elemente der Psychophysik (1860), which measured sensations by experiment, and it inspired him to try the same with memory.^[2][3]

Why is Hermann Ebbinghaus important?

Ebbinghaus matters because he was the first to study memory with controlled experiments and numbers. Until then, experimental psychology had measured only sensations and reaction times, and philosophers such as Johann Friedrich Herbart had argued that higher mental processes could not be studied by experiment.^[3][5] Ebbinghaus ran his first experiments in 1879 and 1880, repeated many of them in 1883 and 1884, and published the results in 1885.^[3] The book appeared in English in 1913 as Memory: A Contribution to Experimental Psychology.^[5]

The book was also a model of method. Ebbinghaus kept his testing conditions constant, worked at fixed times of day, used averages and estimates of error, and reported the problem, method, results and interpretation concisely, as research papers still do.^[3] Reviewing it on its centenary, the memory researcher Henry Roediger credited him with founding “not a school of psychology, but instead a whole field of research”.^[3]

How did Ebbinghaus study memory?

Ebbinghaus memorised lists of nonsense syllables, with himself as the only subject, and measured memory by how much time relearning a list saved.^[5] He built about 2,300 syllables, each a vowel between two consonants, and drew them at random to form lists, so that meaning and prior knowledge would play as small a part as possible. A few of them were in fact real words.^[3][5]

He read each list aloud at a fixed pace of 150 beats per minute until he could recite it once without error.^[5] Later he relearned it the same way. The time saved, as a share of the first learning time, is called savings: if a list took 1,000 seconds to learn and 600 to relearn, savings were 40%. Savings can show that something is retained even when it can no longer be recalled.^[3] His savings over time, and a modern replication, are on the forgetting curve page.

What did Ebbinghaus discover about memory?

Ebbinghaus's main findings concern how fast we forget, how much repetition helps, and how best to spread it out.

• The forgetting curve. Forgetting was fastest soon after learning, then slowed over days and weeks.^[5] He reported it as a table and an equation; he did not draw the curve himself.^[3]
• List length. He could usually recite seven syllables after a single reading. A 12-syllable list needed about 17 repetitions and a 24-syllable list 44, so the work grew much faster than the length.^[5]
• Overlearning, or repeating a list beyond the point where you know it. More repetitions on the first day meant faster relearning the next day: about one repetition saved for every three extra, up to about twice the number needed to learn the list. Beyond that, the gains shrank.^[5]
• Spacing. 38 repetitions spread over three days prepared a list as well as 68 repetitions on a single day. He concluded that spreading repetitions over time is “decidedly more advantageous” than massing them.^[5] This was the first demonstration of what is now called the spacing effect.^[3]

What else did Ebbinghaus contribute to psychology?

Besides his memory research, Ebbinghaus devised an early intelligence test, co-founded a leading journal and wrote widely read textbooks.^[1][2]

• The completion test (1897). Asked by the Breslau school authorities to study whether longer school sessions tired pupils, he designed a test in which pupils fill the gaps in a text. It did not measure fatigue well, but scores matched pupils' standing at school, so it became a measure of general intellectual ability. Gap-filling tasks built on the same idea were still common in intelligence and aptitude tests decades later.^[1][2]
• A journal. In 1890 he founded the Zeitschrift für Psychologie und Physiologie der Sinnesorgane with the Arthur König.^[1][2]
• Textbooks. His Grundzüge der Psychologie (1897–1902) went through many editions.^[2][3] The shorter Abriss der Psychologie (1908) was translated into English the year it appeared and had a new edition on average more than every two years until 1922.^[1]

The Abriss opens with his best-known line: “Die Psychologie hat eine lange Vergangenheit, doch nur eine kurze Geschichte”, usually quoted as “psychology has a long past but only a short history”.^[6] The 1908 English edition renders it “Psychology has a long past, yet its real history is short.”^[7] He meant that people had studied the mind since Aristotle, but steady progress had begun only in the 18th and 19th centuries.^[6]

Do Ebbinghaus's findings still hold?

Yes, his main findings have held up. In 2015 Jaap Murre and Joeri Dros repeated his forgetting experiment, again with a single subject, and obtained results similar to his.^[8] The benefit of spaced practice has been confirmed in hundreds of experiments: a 2006 meta-analysis by Nicholas Cepeda and colleagues found that, for the same total study time, spaced study beat massed study.^[9] Spaced repetition apps build on both findings; see does spaced repetition work? and the spaced repetition schedule.

His design has clear limits. He was experimenter, subject and statistician at once, so he knew what each test was about.^[3] A single subject cannot show whether results hold for other people, which is why replications matter.^[8] And lists of nonsense syllables recited in order are far from how people remember stories or events; later researchers such as Frederic Bartlett (1932) showed that memory also reconstructs the past, an aspect of memory his method was not designed to capture.^[3] He also did little further memory research after 1885, turning to university administration, journal editing and textbooks.^[3]