In 1885 Ebbinghaus published a monograph that laid the foundations for the modern psychological, clinical study of memory. Ebbinghaus showed that it was possible to dramatically improve learning by correctly spacing practice sessions. The efficiencies created by precise spacing are so large, and the improvement in performance so predictable, that for at least the last 100 years, psychologists have been urging educators to use Ebbinghaus’ methods to accelerate human progress.
Psychologist Frank Dempster wrote that “the spacing effect is one of the most remarkable phenomena to emerge from laboratory research on learning.” This was 103 years after Ebbinghaus original monograph. What is sad to realise is that Dempster wrote that in the introduction to a paper titled “The Spacing Effect: A Case Study in the Failure to Apply the Results of Psychological Research”. Dempster and other researchers knew that they possessed a solution to an age old problem; how to remember what has been learned, but no-one seemed to care. The spacing effect has “become a reminder of the impotence of laboratory research”. (https://www.wired.com/2008/04/ff-wozniak/)
Long term memory has 2 components; retrieval strength and storage strength. Retrieval strength is how likely you are to recall something right now, how close it is to the surface of your mind. Storage strength is a measure of how deeply rooted the memory is. We now know that amount of storage strength you gain from practice is inversely related to retrieval strength. The harder you must work to get the answer (retrieve it) the more that memory becomes sealed in. Yet in many classrooms, retrieval strength is what is practiced time and time again and current performance is used to inform the teacher and student of how much progress has been made. Unfortunately, current retrieval performance is a very poor guide as to whether, and what, one might remember in the future.
Learning systems like Kahoot, Quizziz, Duo Lingo, Quilt, Rosetta Stone fall into this trap. With the constant feedback, and rewards for instant retrieval, a student will generate a huge sense of achievement whilst doing little to cement knowledge in the long term memory.
The best way to ensure capture to long term memory is to rehearse something at the very moment you are about to forget it. The problem is that this is a very difficult moment to find. Each fact, word, snippet of knowledge will have its own distinct level of difficulty and its own unique shape on Ebbinghaus’ curve of forgetting. In other words, the best moment to retrieve one fact (and therefore adjust the spacing effect) will be different to another’s. So the real challenge of taking “the most remarkable phenomena” of the spacing effect from the laboratory to the classroom is one of timing. It is also one of understanding.
We, as educators, must understand how learning works, how the knowledge we deliver is encoded in our student’s minds. We must understand how to move from high retrieval strength (but low storage strength) to high storage strength. We must dissuade ourselves and or students that constant high performance on quizzes is a good predictor of future performance (in exams for example, when the storage strength is interrogated). We must teach ourselves and our students that revision is most effective when it feels hard, when they struggle to remember a fact. Herein lies the answer to the question “why do students not revise in ways proven to be most effective”.
To do this, students must have resilience and endurance. They must have faith in the proven science of learning and memory. They must persevere even when it feels hard, when they feel like they are not getting anywhere.
Perhaps it is time to think again about our use of quick fire quizzes that students find easy (because the facts they are being asked to recall have high retrieval strength). Perhaps we must think more deeply about our subject knowledge and curriculum pathways, in the context of how “hard” each fact is and what shape the corresponding forgetting curve will take. Only then will we best be able to help students find that perfect moment, the very moment you are about to forget.
