THE DEVELOPMENT OF EXPERIMENTAL PSYCHOLOGY--
EBBINGHAUS AND G. E. MÜLLER
HERMANN EBBINGHAUS was to a large extent a self-made psychologist, and started as an experimentalist with no University training or tradition in the subject. His inspiration, however, came from Fechner. After taking his doctor's degree in Bonn in 1873, with a thesis on von Hartmmn's philosophy of the unconscious, he spent seven years in private study and in visits to France and England. In a second- hand book shop of Paris he came across a copy of Fechner Elemente. He was seized with the idea of applying experimental methods to the "higher mental processes", and the influence of the English associationists probably caused him to make the attempt in the field of memory. During the next few years he carried out long series of experiments entirely on himself, and in 1885 reported his results in his epoch- making Über das Gedächtnis.
The associationist writers had gradually been attributing more and more importance to the principle of frequency of association as a condition of recall. Ebbinghaus adopted this principle as his fundamental measure for the experimental study of memory. From Fechner's psycho-physics he realized the necessity of eliminating the influence of variable errors by a sufficient number of experiments. In order to repeat the same experiment, he required material of the same difficulty to learn in his successive experiments. As everyone knows, however, some pieces of poetry and prose can be learnt much more easily than others. Here was a problem that the