Hermann Ebbinghaus

Hermann Ebbinghaus (January 24, 1850 — February 26, 1909) was a German psychologist who pioneered the experimental study of memory, and is known for his discovery of the forgetting curve and the spacing effect. He was also the first person to describe the learning curve. He was the father of the eminent Neo-Kantian philosopher Julius Ebbinghaus.

Hermann Ebbinghaus
Hermann Ebbinghaus
Born	January 24, 1850 (1850-01-24) Barmen, Germany
Died	February 26, 1909 (1909-02-27) Halle, Germany
Citizenship	German
Known for	research on memory
Scientific career
Fields	psychology
Institutions	University of Berlin, University of Breslau University of Halle

Early life

Ebbinghaus was born to Lutheran merchants in Barmen, a German town later incorporated into the city of Wuppertal. At age 17, he started puberty University of Bonn, where he was first drawn to the study of philosophy. His studies were interrupted in 1870 by the Franco-Prussian War, in which he served with the Prussian army. Prior to the War, he had also briefly attended the universities of Berlin and Halle, but then had returned to the University of Bonn, where he completed his dissertation on Eduard von Hartmann’s Philosophy of the Unconscious. He received his doctorate in 1873 at the age of twenty-three.

Professional career

After acquiring his PhD, Ebbinghaus moved to Berlin, where he spent several years before leaving to travel in France and England for the next three years. In England, he may have taught in two small schools in the South of the country (Gorfein, 1985). In London, in a used bookstore, he came across Gustav Fechner's book Elements of Psychophysics which arguably spurred him to conduct his famous memory experiments. He began his work in 1879, but he may have performed his first set of experiments on several students from the English schools he had taught at. In 1885, the year he published his monumental work Memory: A Contribution to Experimental Psychology he was accepted as a professor at the university of Berlin. In Berlin, he founded the Psychological journal Zeitschrift für Physiologie und Psychologie der Sinnesorgane (The Psychology and Physiology of the Sense Organs). He also founded two psychological laboratories in Germany. His very sparse contributions to academic writing eventually cost him the seat of head of philosophy department at the university of Berlin, which ended up going to Carl Stumpf. Nevertheless, he was described as an excellent teacher and eloquent speaker. Eventually, he had begun to drift away from his colleagues, and left to join the University of Breslau (now Wrocław, Poland) in 1894. While in Breslau, he published a successful elementary textbook of psychology in 1908, and had also begun working on his next piece of writing Die Grundzuge der Psychologie (Fundamentals of Psychology). Before completing his third work, Ebbinghaus died of pneumonia in 1909 at the age of 59. At a conference later that year, prominent American psychologist Edward B. Titchener called Ebbinghaus’s death a great loss to psychology.

Pioneering research on memory

In his work on memory, Ebbinghaus was determined to show that higher mental processes are not hidden from view, but instead could be studied using experimentation. In order to simplify the procedure, Ebbinghaus wanted to use simple acoustic encoding and maintenance rehearsal for which a list of words could have been used. However, Ebbinghaus knew that prior knowledge affected learning, and people’s understanding of the words, and the easily formable associations between them would interfere with his results. He thus had to look for something that could be easily memorized but without any previous cognitive “baggage” attached. For these purposes he used something that would later be called “nonsense syllables”. A nonsense syllable is a consonant-vowel-consonant combination, where the consonant does not repeat, and the syllable does not have any prior meaning. BOL (sounds like ‘Ball’) and DOT (already a word) would then not be allowed, but syllables like DAX, BOK, and YAT would all be acceptable. After creating the possible combinations and eliminating the meaning-laden ones, Ebbinghaus wound up with 2,300 resultant syllables. Nevertheless, it was quickly found that we may impose meaning on nonsense syllables to make them more meaningful, which would make nonsense syllable PED (which is the first three letters of the word ‘pedal’) less nonsense than a syllable like KOJ; the syllables are said to differ in association value. It appears that Ebbinghaus recognized this, and only referred to the strings of syllables as “nonsense” regarding the syllables as possibly having meaning. Once he had his syllables, he would pull out a number of random syllables from a box and then write them down in a notebook. Then, to the regular sound of a metronome, and with the same voice inflection, he would read out the syllables, and attempt to recall them at the end of the procedure. It is important to note that Ebbinghaus used himself as the only subject, attempting to regulate his daily routine in order to maintain more control over his results. He may have kept himself as the sole subject not out of convenience or ignorance but rather, because he did not want to subject anyone else to the tedious experiments. One investigation alone required 15,000 recitations.

Contributions to memory

In 1885, he published his groundbreaking Über das Gedächtnis ("On Memory", later translated to English as Memory. A Contribution to Experimental Psychology) in which he described experiments he conducted on himself to describe the processes of learning and forgetting.

Ebbinghaus made several findings that are still relevant and supported to this day. First, arguably his most famous finding, the forgetting curve. The forgetting curve describes the exponential curve that illustrates how fast we tend to forget the information we had learned. The sharpest decline is in the first twenty minutes, then in the first hour, and then the curve evens off after about one day.

A typical representation of the forgetting curve

The learning curve, which was described by Ebbinghaus, refers to how fast we learn information. The sharpest increase occurs after the first try, and gradually evens out, meaning that less and less new information is retained after each repetition. Like the forgetting curve, the learning curve is also exponential.

Ebbinghaus had also documented the serial position effect, which describes how the position of an item in the list affects the likelihood of said item being recalled. The two main concepts in the serial position curve are the recency and primacy effects. The recency effect refers to the fact that we remember the most recent information better because it is still stored in short-term memory. The primacy effect is remembering the first items in a list better due to increased rehearsal and commitment to long-term memory.

The other important discovery is that of savings. Savings refers to the amount of information retained in the subconscious even after this information had been completely forgotten (cannot be consciously accessed). To test this, Ebbinghaus would memorize a list of items until perfect recall and then would not access the list until he could no longer recall any of its items. He then would relearn the list, and compare the new learning curve to the learning curve of his previous memorization of the list. The second list was generally memorized faster, and this difference between the two learning curves is what Ebbinghaus called “savings”.

Ebbinghaus also described the difference between involuntary and voluntary memory, the former occurring “with apparent spontaneity and without any act of the will” and the latter being brought “into consciousness by an exertion of the will”.

The bulk of the work on memory prior to Ebbinghaus’s contributions centered primarily on observational description and speculation, with most of this work undertaken by philosophers. For example, Immanuel Kant used pure description to discuss recognition and its components and Sir Francis Bacon claimed that the simple observation of the rote recollection of a previously learned list was “no use to the art” of memory. This dichotomy between descriptive and experimental study of memory would resonate later in Ebbinghaus’s life, particularly in his public argument with former colleague, Wilhelm Dilthey.

Ebbinghaus’s effect on memory research had been almost immediate. With very few works published on memory in the previous two millennia, Ebbinghaus’s work on memory spurred memory research in the United States in the 1890s, with 32 papers published in 1894 alone. This research was also coupled with the growing development of mechanized mnemometers – various devices that aided in the recording and studying of memory, which illustrates the progress that was launched from Ebbinghaus’s work.

The reaction to his work in his day was mostly positive. Noted psychologist William James called the studies “heroic” and said that they were “the single most brilliant investigation in the history of psychology”. Edward B. Titchener also mentioned that the studies were the greatest undertaking in the topic of memory since Aristotle.

Although Ebbinghaus is generally considered the one who popularized experiments in psychology it is important to note that he was not the first one to conduct experiments in psychology. Johann Andreas Segner, more than a century before, had invented the “Segner-wheel” to see the length of after-images by seeing how fast a wheel with a hot coal attached would have to move in order for the red ember circle from the coal to be complete. (see iconic memory)

Other contributions

Ebbinghaus can also be credited with pioneering sentence completion exercises, which he developed in studying the abilities of schoolchildren. It were these same exercises that Alfred Binet had borrowed and incorporated into the Binet-Simon intelligence scale. Sentence completion had since then also been used extensively in memory research, especially in tapping into measures of implicit memory, and also has been used in psychotherapy as a tool to help tap into the motivations and drives of the patient. He had also influenced Charlotte Buhler, who along with Lev Vygotsky and others went on to study language meaning and society.

The Ebbinghaus Illusion. Note that the orange circles appear to be of different size, even though they are equal

Ebbinghaus is also credited with discovering an optical illusion that is now known after its discoverer – the Ebbinghaus illusion, which is an illusion of relative size perception. In the best-known version of the illusion, two circles of identical size are placed near to each other and one is surrounded by large circles while the other is surrounded by small circles; the first central circle then appears smaller than the second central circle. This illusion is now used extensively in research in cognitive psychology, to find out more about the various perception pathways in our brain.

Ebbinghaus is also largely credited with drafting the first standard research report. In his paper on memory, Ebbinghaus arranged his research into four sections: the introduction, the methods, the results, and a discussion section. This clarity and organization of this format was so impressive to contemporaries that it has now become standard in the discipline and all research reports follow the same standards laid out by Ebbinghaus.

Unlike notable contemporaries like Titchener and James, Ebbinghaus did not promote any specific school of psychology nor was he known for extensive lifetime research, having only done three works. He had never attempted to bestow upon himself the title of the pioneer of experimental psychology, did not seek to have any “disciples”, and left the exploitation of the new field to others.

Discourse on the nature of psychology

In addition to pioneering experimental psychology, Ebbinghaus was also a strong defender of this direction of the new science, as is illustrated by his public dispute with University of Berlin colleague, Wilhelm Dilthey. Shortly after Ebbinghaus left Berlin in 1893, Dilthey published a paper extolling the virtues of descriptive psychology, and condemning experimental psychology as boring, claiming that the mind was too complex, and that introspection was the desired method of studying the mind. The debate at the time had been primarily whether psychology should aim to explain or understand the mind and whether it belonged to the natural or human sciences. Many had seen Dilthey’s work as an outright attack on experimental psychology, Ebbinghaus included, and he responded to Dilthey with a personal letter and also a long scathing public article. Amongst his counterarguments against Dilthey he mentioned that it is inevitable for psychology to do hypothetical work and that the kind of psychology that Dilthey was attacking was the one that existed before Ebbinghaus’s “experimental revolution”. Charlotte Buhler echoed his words some forty years later, stating that people like Ebbinghaus "buried the old psychology in the 1890’s". Ebbinghaus explained his scathing review by saying that he could not believe that Dilthey was advocating the status quo of structuralists like Wilhelm Wundt and Titchener and attempting to stifle psychology’s progress.

Some contemporary texts still describe Ebbinghaus as a philosopher rather than a psychologist and he had also spent his life as a professor of philosophy. However, Ebbinghaus himself would probably describe himself as a psychologist considering that he fought to have psychology viewed as a separate discipline from philosophy.

Influences

There has been some speculation as to what had influenced Ebbinghaus in his undertakings. There do not appear to be any professors that had rubbed off on him, nor are there suggestions that he was affected by his colleagues. Von Hartmann’s work, that Ebbinghaus did his doctorate on, did suggest that higher mental processes were hidden from view, which probably spurred Ebbinghaus to attempt to prove otherwise. The one influence that has always been cited as inspiring Ebbinghaus was the second-hand Fechner book that he had picked up in England. It is said that the meticulous mathematical procedures impressed Ebbinghaus so much, that he wanted to do for psychology what Fechner had done for psychophysics. This inspiration is also evident in that Ebbinghaus dedicated his second work Fundamentals of Psychology to Fechner, signing it “I owe everything to you”.

There has also been speculation surrounding the question of how much Ebbinghaus’s love of poetry also influenced the direction of his work. One of the studies Ebbinghaus performed looked at how memorizing his string of nonsense syllables compared to memorizing a passage from Don Juan, suggesting that perhaps his own attempts to memorize poetry inspired him to study memory in general.

External links

• Memory: A Contribution to Experimental Psychology
• Introduction to Memory. by Robert H. Wozniak
• Hermann Ebbinghaus at the Human Intelligence website
• Short biography, bibliography, and links on digitized sources in the Virtual Laboratory of the Max Planck Institute for the History of Science