In his work on memory, Ebbinghaus suggested many principles and methods that have been incorporated in modern psychology. He invented the nonsense syllable, which advanced experimentation by eliminating already-formed associations, in this way equalizing the task for all subjects. He made the first systematic measurements of memory span, showing that seven to eight nonsense syllables could be learned at one reading. He introduced the concept of overlearning, and used the “savings method” to measure its effect. He quantified the process of forgetting, and constructed a standard curve which showed a large initial drop—that is, we forget most rapidly immediately after the learning has taken place. He demonstrated that meaningful material (stanzas from Byron’s Don Juan) could be memorized in one ninth the time of nonsense syllables of equal length, and used the method of relearning to show that the effects of the original learning were still in evidence twenty-two years later.In addition, Ebbinghaus proved that spaced learning is generally superior to massed learning and therefore study periods should usually be broken up, at least for highly factual material. And he showed that when we memorize a series of items, we establish backward as well as forward associations—for example, in A-B-C-D (the hyphens are associations), not only is A linked with B, but B with A, and the same for the other items in the series.As Murphy (1949) has pointed out, Ebbinghaus’ memory experiments were “one of the greatest triumphs of original genius in experimental psychology,” and “set a new direction for psychology as dramatically and as clearly as did anything in this area.” They brought him great acclaim which resulted in an appointment to a professorship at Berlin and later at Breslau and Halle. Between 1890 and his premature death in 1909, he opened up a number of other avenues of research, and presented his results in a lucid, personal style that has been compared with that of William James. While at Berlin, Ebbinghaus collaborated with Arthur Konig in founding the first German journal of general psychology (1890). He also performed experiments on brightness contrast, which he incorporated in a theory of color vision published in 1893. At Breslau he made a number of contributions to mental testing. The most noteworthy was the Ebbinghaus Completion Test which consisted of sentences with missing words to be filled in by the subject—for example, “The . . . rises morning and . . night.” By applying this test, which is still used, he showed that bright students did better than poor students and older children better than younger. These investigations, carried out in 1897, anticipated the more systematic work of Binet in 1903.Ebbinghaus’ final book, Foundations of Psychology (1902) was a highly successful and influential text. He was engaged in revising it at the time of his sudden death in 1909, a loss that was deeply felt by the academic community. In evaluating his contributions, Boring (1950) suggests that his importance lies not merely in his specific discoveries, but in helping to free psychology from its philosophical heritage and in stimulating others to investigate problems that cannot be solved by philosophical methods. In commenting on the fact that problems in learning and memory had rarely been approached scientifically, Ebbinghaus himself coined the apt and oft-quoted remark, “Psychology has a long past, but only a short history.”