Hermann Ebbinghaus and Human Memory Experiments
Biography: Ebbinghaus was born near Bonn, Germany. His father was a merchant. Ebbinghaus attended the local gymnasium before enrolling at the University of Bonn to study philology and history. He also studied at the University of Halle and the University of Berlin. After the outbreak of the Franco-Prussian War (1870-1871), he joined the army and served as a lieutenant. When he left the army, he returned to Bonn and earned his PhD in philosophy. He spent the next seven years traveling in France and England supporting himself by tutoring. During that period he found a used copy of Fechner’s Psychophysics. Fechner’s work in sensation and perception. It inspired Ebbinghaus to use the methods in that book and to modify them to study memory.
Contributions: No one before him had attempted to experiment on memory. Before Ebbinghaus began his experiments on memory that topic was firmly within the grasp of philosophy. To study memory he created new techniques for experimentally manipulating items to remember and new ways of measuring them. The nonsense syllable was the key to the new technique. It was a consonant-vowel-consonant combination that was not a word. He realized early on that he needed items to place into memory with which he had little or no previous experience. Among the examples he used (in German, naturally) were: ZAT, BOK, and SID (Boring, 1950, p. 388), nonsense syllables that would work in English as well. Ebbinghaus wished to study memory in its purest form, that is, without linking it to items already stored in the mind due to experience. He proceeded to memorize thousands of lists randomly made up from the 2,300 nonsense syllables he had created. To measure his own memory (he was the only participant), he measured the time it took him to learn a particular list for the first time, and later, after a predetermined interval (enough time to forget the list), measure the time it took him to relearn it. In each instance, the criterion of learning was reciting the list without any errors. He discovered that it always took him less time to learn the list on the second trial. He called the results a savings score because he was saving time when he learned the list the second time. From his data, he constructed a graph showing that the interval between the first trial and the second trial was the most important feature. That graph, now known as Ebbinghaus’s curve of forgetting, has stood the test of time and been replicated countless times. He also discovered other facts about memory including that the savings score improved with the number of repetitions made on the first trial and when practice was distributed over time (Schacter, 2001).
Neisser and Hyman (2000, p. xiii) refer to Ebbinghaus’s approach to as “the high road” to the study of memory. He was trying to study memory in its purest form. In contrast, the “low road” to memory is studying it in natural contexts, e.g., answering questions such as, “Where did I leave the car keys?” In those contexts, the importance of previous experience becomes paramount. In practice, however, it is impossible to study memory in its pure form. Research has revealed that nonsense syllables, too, carry meaning. But, it is possible to choose nonsense syllables that have been shown to carry less meaning than others (Hull, 1933b).
Ebbinghaus had begun his memory research during the time he was on his own. He continued it after being hired to teach at the University of Berlin in 1880. There, he carefully replicated his earlier experiments and finally published them five years later as a book, his first publication other than his PhD thesis. That book, Über das Gedächtnis (Concerning Memory) catapulted him to instant fame. Paradoxically, he never published any other research in memory afterward. Ebbinghaus moved on to other topics and left the working out of memory details to others, notably G. E. Müller and his coworkers.Schacter (2001, p. 143) listed seven topics that emanated from other laboratories based upon Ebbinghaus’s pioneering work: “repetition effects, the curve of forgetting, stimulus attributes and presentation modality, individual differences, interference and inhibition, methods of learning, and recognition and affect.” That this list sounds modern is testament to Ebbinghaus’s breakthrough.
His later career, however, was not like most of the other early psychologists. He did not publish as extensively as his contemporaries and that probably cost him his chance to advance at the University of Berlin. That chair went to Carl Stumpf instead. Ebbinghaus moved to the University of Breslau and later to the University of Halle. He died of pneumonia suddenly in 1909. He did, however, perform several other important services for early psychology. One was helping found the second European journal of psychology, the Journal of Psychology and Physiology of the Sense Organs to provide an alternative outlet for psychological research. Ebbinghaus also wrote two influential textbooks that were praised for their readability and scientific content. One of them opened with the now famous and oft quoted line, “Psychology has a long past, but only a short history.”
He was an early worker in the development of psychological tests for children. Like Brentano, he did not supervise many PhD theses, so he left little intellectual legacy behind other than his first and monumental work in memory. That, though, was more than enough. More than anyone else of his time he opened doors to areas of psychology that no one else had even imagined existed before him. One of his students, Oswald Külpe, presided over a group of researchers at the University of Würzburg whose research led to the first major crisis in the young science of psychology.