Hermann Ebbinghaus – a pioneer of memory research
Hermann EbbinghausHermann Ebbinghaus (January 24, 1850 — February 26, 1909) was the founder of experimental psychology of memory. Among his most famous discoveries are the forgetting curve, the learning curve and the spacing effect. Ebbinghaus published his groundbreaking results in a monograph entitled “Über das Gedächtnis” (1885), which was later translated into English as “Memory: A Contribution to Experimental Psychology” (1913).
Life of Hermann Ebbinghaus
Hermann Ebbinghaus was born on January 24th, 1850 in Barmen (now part of the German city Wuppertal). His father, a wealthy Lutheran merchant encouraged him from early childhood on to pursue an academic career. At the age of 17 Ebbinghaus enrolled at the University of Bonn (Rheinische Friedrich-Wilhelms-Universität) to study history and philosophy. In 1868 he became member of the Corps Guestphalia Bonn (a student corporation in German-speaking countries). His studies were interrupted in 1870 due to the Franco-Prussian War in which he enlisted as a member of the Prussian army.
After the war Ebbinghaus continued his education at the universities of Halle and Berlin. He eventually returned to the University of Bonn to complete his dissertation on Eduard von Hartmann’s philosophy of the Unconscious. In 1873, at the age of twenty-three, Ebbinghaus received his doctorate in philosophy.
Hermann Ebbinghaus then moved to Berlin where he conducted independent post-doctoral studies for several years before leaving to travel in France and England for three years. A pivotal point in his life was when he discovered during his travels in London Gustav Fechner’s book “Elements of Psychopysics” which spurred his interest in conducting studies in experimental psychology, notably on memory.
Ebbinghaus began his first set of memory experiments late in 1878, which took him more than a year. He then became a private lecturer at the University of Berlin in 1880 where he continued his studies of memory. In the years 1883-1884 Hermann Ebbinghaus repeated and refined many of his original experiments from 1878-1880. In 1885 finally he published his seminal work in the monograph “Über das Gedächtnis” (1885), which was later translated into English under the title “Memory: A Contribution to Experimental Psychology” (1913).
Hermann Ebbinghaus was an energetic, enthusiastic, eloquent and witty lecturer who became a popular professor, highly regarded by university teachers and loved by students. He became excited about new problems that arose and encouraged discussion thereof. Ebbinghaus was widely known and his reputation brought even American students during their travels through Europe to Berlin. Cornell University offered him a position, Ebbinghaus however preferred to remain in Europe.
In 1886 he founded the laboratory for experimental psychology at the University of Berlin.
In 1890 he co-founded the “Zeitschrift fur Psychology und Physiologie der Sinnersorgane (Journal of Psychology and Physiology of the Sense Organs)” with Arthur König. His interest in the journal was mostly spurred by the possibility to publish work emanating from places other than Wundt’s Leipzig laboratory. The journal was often credited with the international advancement of psychological study. At the time of Ebbinghaus’s death in 1909 the journal “…had probably more fully represented the progress of psychology during these twenty years than any other journal…” of the times (Woodworth, 1909).
In the years following Ebbinghaus became interested in studying vision and published a theory of color-vision in 1893.
Between 1894 and 1905 Hermann Ebbinghaus became a professor at the University of Breslau (today Wroclaw, Poland). In 1894 he founded another laboratory of experimental psychology at the University of Breslau. From 1905 to 1908 he became a professor at the University of Halle.
In 1909, Hermann Ebbinghaus died of pneumonia in Breslau.
The works of Hermann Ebbinghaus
The works of Ebbinghaus are the results of hard work and a lot of experimentation in the lab. Ebbinghaus, however, spent considerable amount of time not only in the laboratory but searching for funding and financial sources to continue his research and to pay his students. His time and efforts were well spent – the results of his research count today as fundamental contribution to the field of psychology. And Ebbinghaus is considered a pioneer in memory research.
The forgetting curve
In the field of psychology the term forgetting curve describes how the ability of the brain to retain information decreases in time.
Hermann Ebbinghaus was the first to study the forgetting behavior in an experimental, scientific way. In his groundbreaking research he studied on himself the memorization and forgetting of nonsense three letter words. Examples of such words are KAF or WID. Words, which had a meaning or easily alluded to a known word were excluded. (See for more details Ebbinghaus memory experiments).
Ebbinghaus performed a series of tests on himself over various time periods. He then analyzed all his recorded data to find the exact shape of the forgetting curve. He found that forgetting is exponential in nature.
Ebbinghaus published his findings in 1885 in his book “Über das Gedächtnis (Memory: A Contribution to Experimental Psychology)”.
The forgetting curve of information which has been learned only once. The retention of the information decays in an exponential way.
Here is a plot of a typical forgetting curve. At the beginning your retention is 100% since this exactly the point in time when you actually learned the piece of information. As time goes on the retention drops sharply down to around 40% in the first couple of days.
The forgetting curve is exponential. That means that in the first days the memory loss is biggest, later (as you can see in the forgetting curve at the right side) you still forget but the rate at which you forget is much, much slower.
The forgetting curve clearly shows that in the first period after learning or reviewing a piece of information we forget most!
The speed with which we forget any information depends on a number of different factors:
•How difficult is the learned material? How easy is it to relate the information with facts, which you know already?
•How is the information represented?
•Under which condition are you learning the material? Are you stressed?
•Are you fully rested and have you slept enough?
While all individuals differ in their capacity to learn and retain information the shape of the forgetting curve for base tests (such as nonsensical words) is nearly identical.
Thus the differences in learning capacities come from different acquired learning behaviors. Some individuals are able to transform the piece of information to a memory representation that is more suitable for them (for example audio oriented learners or visually oriented learners). Also some people have naturally a better capacity to use memory hooks and other mnemonic techniques to remember more easily and relate to information, which they know already.
However these techniques can be learned and applied by anybody.
What can you do to improve your memory?
1.Learn to connect new information with what you know already. Use memory hooks and other mnemonic devices to represent the new information in terms of already familiar concepts.
2.Activate the information in regular, spaced intervals. It is important that the recall is active, that is, you should not just re-read the new information but reply to a question about the new information. Like that your brain will be forced to activate the memory and to deepen the neural connections.
3.Use spaced repetitions. Spaced repetition (in particular spaced repetitions software) enables you to calculate the exact time when you profit most from a review: the time just before forgetting.
The image shows what happens to the learning curve after your review the piece of information several times. Every time you repeat it your retention rate goes back to 100% since you just reviewed the information. And every time forgetting sets in in the very same way as if you learned the item only once. What is however drastically different is the speed at which you forget. As you can see in the image the forgetting curve becomes flatter and less steep with every additional review, provided the review is made at the correct time (see spacing effect).
Every time you activate and review the new information the memory traces become stronger. The stronger the memory the longer you are able to recall the information. Therefore the learning curve and the corresponding retention rate for that piece of information becomes flatter. This means that the interval for the next repetition becomes longer. For some information the interval can become several years.
Learning from the forgetting curve – how not to learn
Typical cramming sessions in school, for example quickly learning vocabulary lists before a test are usually useless from a long term perspective. Most students don’t remember more than 10-20% after about half a week. The effort you made to learn these lists was in vain — you lost 80-90% of the learned material.
Test your memory yourself
Don’t just trust us with above numbers.
The spacing effect
In the field of psychology the spacing effect refers to the finding that information, which is presented over spaced intervals is learned and retained more easily and more effectively.
In particular it refers to remembering items in a list. You can study them in fewer times over a long period of time (spaced presentation) or repeatedly in a short period of time (massed presentation). It was found that spaced repetition is much more beneficial both time-wise and retention-wise.
In simple words:
If your reviews are farther apart in time you will benefit much more than when the repetitions are close together.
An example for the spacing effect
Let’s take a practical example. Let’s say you have freshly learned something:
In method 1 (massed repetition) you repeat it immediately ten times in a row.
Do you think it helped you to remember it longer? Probably not.
In method 2 (spaced repetition) you make the first repetition after say 1 hour, the second after 5 hours, the third after 1 day, the fourth after 3 days, and so on … until finally the tenth repetition after about eight months.
All experimental findings conclude that method 2 is much more effective.
Although you spent exactly the same amount of time for the repetitions in both cases it is very likely that you will have forgotten the piece of information with method 1 after about 1-2 days, whereas using method 2 (spaced repetition) you will still know it after almost a year.
This fact was first found by the German psychologist Hermann Ebbinghaus. He published his findings in his book “Über das Gedächtnis. Untersuchungen zur experimentellen Psychologie (Memory: A Contribution to Experimental Psychology)” in 1885.
The spacing effect was confirmed in many different memory tasks such as recognition, frequency estimation, free recall and cued recall.
The spacing effect is extremely powerful and robust. That means:
•It works for many types of learning.
•You can depend on it.
In short: it just works!
Why is the spacing effect effective? How can you apply it in your studies?
Many experiments were performed on this question and the following simple fact was found:
The closer you are to forgetting a piece of information the more you will profit from reviewing.
It is important, however, that you don’t wait too long. After the point of forgetting it is almost as difficult to relearn the piece of information as the first time you learned it. That’s why it is necessary to know exactly when you will forget a piece of information. Impossible? No. The spaced repetition software Flashcard Learner does all the work for you. It adapts to your learning and forgetting patterns and calculates exactly when you are most likely to need a review before your forget a flashcard.
Why does the spacing effect work?
Why does the spacing effect work? All experiments conducted suggest that the spacing effect is a fundamental property to all biological life forms. Spaced repetition works on all tested animals, not just for humans. The spacing effect works, because that’s how the nerve cells in our bodies store information. It is a physiological fact.
Recent experiments in rats have found that the spacing effect has a clear neuro-physiological basis: Sisti et al. (2007) showed that neural longevity in the hippocampus of rat brains improved significantly with spaced repetition. (The hippocampus is a region in the brain, which is important for long-term storage of information.)
Despite the well researched facts of the spacing effect for over a century, the traditional educational practice largely ignores it. With detrimental effects: how much do you still remember from your high-school or university time?
You can apply the spacing effect and improve your learning and your performance in school simply by learning the material and reviewing at regular and increasing intervals. Like that you will know more and forget much less
The best way however to improve your learning is to use a spaced repetition software, which keeps track of your learning progress and calculates exactly when you are about to forget a piece of information. That’s when you profit most from the repetition.
H.M. Sisti, A.L. Glass, T.J. Shors: Neurogenesis and the spacing effect: Learning over time enhances memory and the survival of new neurons. Learn. Mem. 2007;14(5):368-75.
Spacing Effect states that we learn material more effectively and easily when we study it several times spaced out over a longer time span, rather than trying to learn it in a short period of time.
As you can guess, this means that cramming for an exam the night before is not as effective as studying material each night over a week or some period of time. There's one caveat - this holds true for material you want to store for a long time (i.e., really store it in memory), whereas cramming can work to store information for short periods of time.
The learning curve
In psychology the learning curve denotes a graphical representation of the rate at which you make progress learning new information.
When you learn something new repetition is essential. Through repetition you become more efficient and more effective at any challenge, which you pose yourself. The progress you make during the learning and repetition phases can be represented graphically like in the plot below. Scientific studies on memory and acquisition of motor skills have shown that the learning curve looks as follows: in the beginning, when what you have to learn is very new, the progress you make is very slow. However, if you keep training and repeating something interesting happens. Your brain starts adjusting to the challenge and suddenly the progress becomes much more accelerated. This is the phase, where you make the most progress. Once you reach a certain level of skill and knowledge you enter the phase of diminishing returns. The better you become at the task the less you still can make progress in the learning curve. You start mastering the new knowledge or skill and your brain has adapted and adjusted to the challenge – you hit the bounds of the skill or you know all there is to know in that field – you have reached a plateau. The plateau is generally not flat, it is just much, much harder to make significant progress. Most people then are satisfied with the results and say that they have learned the new knowledge or skill as well as it can be learned. You could call it the individual maximum competence for a given skill.
typical learning curve while learning new information
Most likely you have experienced the learning curve first hand. Whenever you delve into a new and very complex field your progress at the beginning of the learning curve is very slow. This is mostly due to the fact that you first have to familiarize yourself with the topic, get an overview what’s going on, understand the basic definitions and terminology etc.
Once you are over this initial phase, whatever you learn starts slowly making sense. In fact, once you learned the basic vocabulary, your understanding improves significantly and you make a lot of progress learning what really matters in that field. This is when all the scattered facts begin to interconnect and you start “putting it all together”. You continue making fast progress until you reached the end of what there is to learn in the given field and when all is left are the boring details, which do not change the big picture any more. Then your progress in the learning curve slows down until you reach your individual plateau.
The first scientific study of the learning curve was performed by Hermann Ebbinghaus. Ebbinghaus learned nonsensical three letter words such as “WID” “KOR” “ZIF” etc. and recorded his progress. He found that when learning lists of such nonsensical words the time spent learning a given number of words increases drastically with the number of words.
While the learning curve originally used in psychology and memory research has a clearly defined meaning, it has become increasingly popular in other fields as well. Therefore different terminologies have been coined such as “experience curve”, “progress function”, “progress curve”, “improvement curve”, “cost improvement curve”, “start-up curve”, and “efficiency curve”. These different names however denote essentially the same behavior. An slow beginning followed by an accelerated rate of increase and a subsequent reaching of a plateau. All these processes are described by a so called S-curve.
The steep learning curve
A colloquial term that is frequently used is “this product has a steep learning curve”. Interestingly this is exactly the opposite of the original definition. When you say e.g. “quantum thermodynamics has a steep learning curve” you intend to say that it is rather difficult to understand and master it. A steep learning curve however, as defined in learning psychology, means that you make rapid progress. This is the part in the middle of above plot where things are starting to make sense and you move ahead quickly – this is where learning is easiest!
Probably the term came to be because you can consider its figural meaning: if you hike on a learning curve, steep is probably associated with frustration and strenuous climbing. Not so!
Next time you hear somebody talk about a steep learning curve – just smile.