Do we immediately forget information after it has been taught?
The first academic reference to retrieval practice is by Hermann Ebbinghaus, a German psychologist (1850 – 1909) who pioneered an experimental study of memory, most known for his discovery of the forgetting curve and the spacing effect.
Before Ebbinghaus, the “study of learning was restricted to philosophy” (Polk, 2018) and not necessarily the human mind. Until the late 19th century, most “scientists and philosophers assumed that learning could not be studied scientifically.”
However, this changed in 1885 when Ebbinghaus published his book, Über das Gedächtnis (About memory).
The field of neuroscience was born! To this day, his seminal research still influences our work. Inspired by Ebbinghaus, Mary E. Abbott was one of the first to publish in 1909.
Sharing the Forgetting Curve (1885) with students
In 2007 when I became a senior school leader, I was catapulted in front of hundreds of teachers and thousands of pupils, responsible for whole-school teaching and learning. I remember standing in front of hundreds of year 11 students, advising and motivating them for revision during the exam season. (You can see some blog posts from 2010 – 2017.)
I knew this was far too late in their school career for them to be taught this valuable information. This was the default model for many school leaders at the time. A decade later, we now know revision should start on day one of school!
I introduced those pupils (and many more) to Hermann Ebbinghaus and his forgetting curve as it is known (see image below).
His hypothesis examined the fact that we forget information, and the speed at which we forget it: in other words, memory declines over time.
Forgetting curve mutations 136 years later …
136 years later, I would like to add some critique.
If you search online for the ‘forgetting curve’ – I would advise you to be cautious of all the fancy graphics presented – most suggest, for example, that you will forget 20 per cent of everything that you have read in this blog post within the hour, and up to 80 per cent within one month – with no regular retrieval. Below is a typical example, something I showed students in my assemblies.
Image: The Learning Brain (Polk, 2018)
In his research, Ebbinghaus was the ONLY participant. Not many teachers know this. Not that it degrades his research in any way, shape or form, but what he tested himself on (the spaced effect) was how the forgetting curve came to be.
Ebbinghaus wanted to investigate learning in a way that wasn’t spoiled by what he already knew. Thus, he decided to try to learn lists of meaningless syllables, a ‘nonsense syllable’ used to design a controlled experiment to measure retention. Words that he did not recognise or connected characters that didn’t mean anything.
He studied this list until he could repeat them twice in a row without errors. His research was also incomplete and took him 5 years to conduct.
He invented a ‘savings method’ to help shape learning and discovered that distributing learning trials over time is more effective in memorising. Of course, we know the latter part of this sentence is correct. Retrieval matters. However, the percentage of information that is lost could be impossible to predict.
We all have different cognitive abilities, and, dare I say, Ebbinghaus was the only person in his trial.
Is it permissible for me to say that the forgetting curve graphic may be true in this research, but not applicable in other contexts?
- For example, how does the forgetting curve shape up when we retrieve UNfamiliar information?
- How would this theory stack up with other participants, tested on things they already know?
- How does the forgetting curve map out for 4 years olds? 16 year olds? You and I?
- How does the forgetting curve evolve if we were tested on things we already knew? Do we still have a 90 per cent drop-off after one hour?
I suspect I’m not the first to think about these things, but I may be one of the few educators to question the reliability of the forgetting curve without first understanding what the research aimed to test. If you were a school leader in the last decade, I suspect you (like I) also shared this graphic with your students. Today, in a climate where more teachers have access to research, we should all be questioning some of the things we (first) shared confidently in a new light.
Be conscious of any alluring graphics you find without unpicking the original research.
If you are interested in neuroeducation, the above is some seminal research I unpick in my book, Guide To Memory.
This is such an interesting article. Although you have to question the reliability of Ebbinghaus’ original experiment, I do think from personal and professional experience that his conclusions are probably not far off the mark. Another significant consideration for me is whether the learning is entirely new or whether we possess any prior knowledge that our new learning can connect to. One will dramatically increase the likelihood of forgetting whilst the latter will increase our chances of remembering it significantly.
It does make you really think about Ebbinghaus’ original experiment, and how it has shaped retrieval practice research.