Hermann Ebbinghaus
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|---|---|
Hermann Ebbinghaus
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| Born | January 24, 1850 |
| Died | February 26, 1909 (aged 59) |
| Citizenship | German |
| Known for | Serial position effect, Über das Gedächtnis |
| Scientific career | |
| Fields | Psychology |
| Institutions | University of Berlin, University of Breslau, University of Halle |
| Influences | Gustav Fechner |
| Influenced | Lev Vygotsky, Lewis Terman, Charlotte Bühler, William Stern |
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 neo-Kantian philosopher Julius Ebbinghaus.
Early life
Ebbinghaus was born in Barmen, in the Rhine Province of the Kingdom of Prussia, as the son of a wealthy merchant, Carl Ebbinghaus. Little is known about his infancy except that he was brought up in the Lutheran faith and was a pupil at the town Gymnasium. At the age of 17 (1867), he began attending the University of Bonn, where he had planned to study history and philology. However, during his time there he developed an interest in philosophy. In 1870, his studies were interrupted when he served with the Prussian Army in the Franco-Prussian War. Following this short stint in the military, Ebbinghaus finished his dissertation on Eduard von Hartmann's Philosophie des Unbewussten
(philosophy of the unconscious) and received his doctorate on August
16, 1873, when he was 23 years old. During the next three years, he
spent time at Halle and Berlin.
Professional career
After acquiring his PhD,
Ebbinghaus moved around England and France, tutoring students to
support himself. In England, he may have taught in two small schools in
the south of the country (Gorfein, 1885). In London, in a used bookstore, he came across Gustav Fechner's book Elemente der Psychophysik (Elements of Psychophysics),
which spurred him to conduct his famous memory experiments. After
beginning his studies at the University of Berlin, he founded the third
psychological testing lab in Germany (third to Wilhelm Wundt and Georg Elias Müller). He began his memory studies here in 1879. In 1885 — the same year that he published his monumental work, Über das Gedächtnis. Untersuchungen zur experimentellen Psychologie, later published in English under the title Memory: A Contribution to Experimental Psychology — he was made a professor at the University of Berlin, most likely in recognition of this publication. In 1890, along with Arthur König, he founded the psychological journal Zeitschrift für Physiologie und Psychologie der Sinnesorgane ("The Psychology and Physiology of the Sense Organs'").
In 1894, he was passed over for promotion to head of the philosophy department at Berlin, most likely due to his lack of publications. Instead, Carl Stumpf received the promotion. As a result of this, Ebbinghaus left to join the University of Breslau (now Wrocław, Poland), in a chair left open by Theodor Lipps (who took over Stumpf's position when he moved to Berlin). While in Breslau,
he worked on a commission that studied how children's mental ability
declined during the school day. While the specifics on how these mental
abilities were measured have been lost, the successes achieved by the
commission laid the groundwork for future intelligence testing. At Breslau, he again founded a psychological testing laboratory.
In 1902, Ebbinghaus published his next piece of writing entitled Die Grundzüge der Psychologie (Fundamentals of Psychology). It was an instant success and continued to be long after his death. In 1904, he moved to Halle where he spent the last few years of his life. His last published work, Abriss der Psychologie (Outline of Psychology) was published six years later, in 1908. This, too, continued to be a success, being re-released in eight different editions. Shortly after this publication, on February 26, 1909, Ebbinghaus died from pneumonia at the age of 59.
Research on memory
Ebbinghaus was determined to show that higher mental processes could actually be studied using experimentation,
which was in opposition to the popularly held thought of the time. To
control for most potentially confounding variables, Ebbinghaus wanted to
use simple acoustic encoding and maintenance rehearsal for which a list of words could have been used. As learning
would be affected by prior knowledge and understanding, he needed
something that could be easily memorized but which had no prior
cognitive associations. Easily formable associations with regular words
would interfere with his results, so he used items that would later be
called "nonsense syllables" (also known as the CVC trigram). A nonsense syllable is a consonant-vowel-consonant
combination, where the consonant does not repeat and the syllable does
not have prior meaning. BOL (sounds like "Ball") and DOT (already a
word) would then not be allowed. However, syllables such as DAX, BOK,
and YAT would all be acceptable (though Ebbinghaus left no examples).
After eliminating the meaning-laden syllables, Ebbinghaus ended up with
2,300 resultant syllables.
Once he had created his collection of 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. One investigation alone required 15,000 recitations.
It was later determined that humans impose meaning even on
nonsense syllables to make them more meaningful. The nonsense syllable
PED (which is the first three letters of the word "pedal") turns out to
be less nonsensical than a syllable such as 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" in that the syllables might be less
likely to have a specific meaning and he should make no attempt to make
associations with them for easier retrieval.
Limitations to memory research
There
are several limitations to his work on memory. The most important one
was that Ebbinghaus was the only subject in his study. This limited the
study's generalizability
to the population. Although he attempted to regulate his daily routine
to maintain more control over his results, his decision to avoid the use
of participants sacrificed the external validity of the study despite sound internal validity.
In addition, although he tried to account for his personal influences,
there is an inherent bias when someone serves as researcher as well as
participant. Also, Ebbinghaus's memory research halted research in
other, more complex matters of memory such as semantic and procedural memory and mnemonics.
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, Ebbinghaus made a set of 2,300 three letter
syllables to measure mental associations that helped him find that
memory is orderly. Second, and arguably his most famous finding, was the
forgetting curve. The forgetting curve describes the exponential loss of information that one has learned.
The sharpest decline occurs in the first twenty minutes and the decay
is significant through the first hour. The curve levels off after about
one day.
A typical representation of the forgetting curve
The learning curve
described by Ebbinghaus refers to how fast one learns information. The
sharpest increase occurs after the first try and then gradually evens
out, meaning that less and less new information is retained after each
repetition. Like the forgetting curve, the learning curve is
exponential. Ebbinghaus had also documented the serial position effect,
which describes how the position of an item affects recall. The two
main concepts in the serial position effect are recency and primacy. The
recency effect describes the increased recall of the most recent
information because it is still in the short-term memory. The primacy
effect causes better memory of the first items in a list due to
increased rehearsal and commitment to long-term memory.
Another important discovery is that of savings. This refers to the amount of information retained in the subconscious even after this information cannot be consciously accessed. 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".
Prior to Ebbinghaus, most contributions to the study of memory
were undertaken by philosophers and centered on observational
description and speculation. 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. However, more than a century before Ebbinghaus, Johann Andreas Segner invented the "Segner-wheel" to see the length of after-images by seeing how fast a wheel with a hot coal attached had to move for the red ember circle from the coal to appear complete.
Ebbinghaus's effect on memory research was almost immediate. With
very few works published on memory in the previous two millennia,
Ebbinghaus's works spurred memory research in the United States in the 1890s, with 32 papers published in 1894 alone. This research was coupled with the growing development of mechanized mnemometers, or devices that aided in the recording and study of memory.
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.
Other contributions
Ebbinghaus
can also be credited with pioneering sentence completion exercises,
which he developed in studying the abilities of schoolchildren. It was
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 Bühler, who along with Lev Vygotsky and others went on to study language meaning and society.
The Ebbinghaus Illusion. Note that the orange circles appear of different sizes, despite them being equal.
Ebbinghaus is also credited with discovering an optical illusion now known after its discoverer—the Ebbinghaus illusion,
which is an illusion of relative size perception. In the best-known
version of this 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. The 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.
After Ebbinghaus worked on memory, he also had a contribution
with color vision. In 1890, Ebbinghaus came up with the double pyramid
design where corners were rounded off.
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 done only
three works. He 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 Bühler
echoed his words some forty years later, stating that people like
Ebbinghaus "buried the old psychology in the 1890s". 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 influenced Ebbinghaus in his
undertakings. None of his professors seem to have influenced him, nor
are there suggestions that his colleagues affected him. Von Hartmann's
work, on which Ebbinghaus based his doctorate, did suggest that higher
mental processes were hidden from view, which may have spurred
Ebbinghaus to attempt to prove otherwise. The one influence that has
always been cited as having inspired Ebbinghaus was Gustav Fechner's two-volume Elemente der Psychophysik.
("Elements of Psychophysics", 1860), a book which he purchased
second-hand 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 Principles of Psychology to Fechner, signing it "I owe everything to you."
Selected publications
- Ebbinghaus, H. (1885). Memory: A contribution to experimental psychology. New York: Dover.
- Ebbinghaus, H. (1902). Grundzüge der Psychologie. Leipzig: Veit & Co.
- Ebbinghaus, H. (1908). Psychology: An elementary textbook. New York: Arno Press.
