What is the SuperMemo Algorithm and How to Use it to Your Advantage?
You may have heard of the saying “Use it or lose it”, which perfectly describes how our brains handle new information. Human beings are “deletion creatures”. Being bombarded by billions of bits of information every single day, and yet only a small fraction of those remain in our memory. The rest is ruthlessly filtered out.
In order for the new information to stick, revision is necessary. Because only by exposing to the same information multiple times over a period of time can your brain perceive the importance of it, therefore granting it access to your long-term memory.
For a small amount of information say ten new foreign words in total, you can afford to go over them multiple times each day for weeks or even months. But if the task now is to learn 10,000 words, such as revision schedule becomes impractical.
Spaced repetition is the answer to such a problem. It helps to minimise the total time spent to revise each piece of information by setting up a revision schedule that is more manageable. Simply put, if the study material is easy and you are already very familiar with it, you don’t need to review it as often as those you are constantly having trouble remembering.
Spaced repetition is a simple concept to understand, but to work out the best revision intervals is not quite simple. The revision pattern suggested by the original Leitner system using boxes only gives a rough indication of the revision frequency.
In addition, it does not take into consideration the level of the difficulty of the learning material. That is why a more sophisticated system such as the SuperMemo algorithm is much better.
SuperMemo stands for “Super Memory”, which is a learning system developed by a Polish researcher Dr Piotr Wozniak since 1985. He took the spaced repetition principle to the next level by using an algorithm to calculate the revision schedule more precisely for each piece of learning material.
From its conception, 18 versions of the SuperMemo algorithm have been developed. The first version SM-0 is the original non-computer based algorithm which can be implemented using just a pen and paper. SM-2 is the first computer-based version which is less sophisticated than its successors, but more popular among other flashcard program developers, possibly because it is much easier to understand than the later versions.
For each piece of the learning material, the first two repetitions follow a fixed pattern: the first repetition occurs one day after, while the second repetition occurs 6 days after the first one. The time intervals among further repetitions depend on two factors, namely the repetition number (n), and the easiness factor (EF).
The EF is influenced by the user’s response to the question on a 0-5 grade scale with 0 being not learnt and 5 being very familiar. It is calculated using the following formula
where: EF’ is the new value of the easiness factor, EF is the old value and q is the quality of the response.
The EF’ is then used to calculate the interval between the current and the next revision session.
Right now you may have been turned off by the scary looking formula, the good news is that as a user you never need to worry about the nitty-gritty of mathematical calculations. Computer programs have been developed to handle the calculation, while users can concentrate on setting up what to be learnt and doing the revisions.
Piotr’s company SuperMemo World has released its own proprietary software SuperMemo which runs mainly on windows. The current version v17 will set you back $66. But you get all the whistles and bells of the latest version of the algorithm from the original developer. Mac users will need to rely on the web version of the app which is subscription based.
If you are on a tight budget, there are also alternatives. Anki is a popular open-source software which can run on literally any device. It uses the SuperMemo SM-2 algorithm which according to the developer is less complicated without sacrificing too much learning efficiency. It is also less susceptible to bugs and scheduling errors.
Anki is relatively easy to use. You set up each piece of information you want to learn in a question and answer pair. Related information can be grouped into the same deck which is just a group of cards. How you organise your decks is entirely up to you. For example, you can group the cards based on the broad subject such as Language, Biology, Medicine or Law. You can also group the cards based on learning outcomes such as Exam preparation, medium term, or long term etc.
A word of caution:
Even though computer programs can simplify the process of spaced repetition, a couple of rules you have to stick to in order for you to benefit most out of the entire learning experience.
1.You have to understand the information before you can memorise it.
The strongest memory is built on context, which provides anchor points for the new information to grab hold on. For example, a single foreign word by itself is meaningless unless you can understand how it is used in the new language. For that reason, a flashcard program can never replace textbooks or study courses. It can only be used as a supplement tool to help you retain what you have already learnt and comprehended.
2.Don’t miss a day.
Using a program like SuperMemo or Anki requires you to stick to the schedule determined by the program with discipline. When you stick to a routine and check what needs to be learnt every day, long-term learning becomes possible. And you will be able to increase the amount of information you can learn but decrease the time needed to learn over time as you become more skilled at this process.
On the other hand, when you miss a day here and there, your daily study load will begin to pile up. The longer you wait, the longer you will have to study each day just to catch up, and less-motivated you will feel to continue learning using spaced repetition.
So overall, the SuperMemo algorithm is a much-improved scheduling system to manage your learning material. You can take advantage of this system by creating question and answer cards using a computer based software based on the SM algorithm. The key to the long-term success is to first understand what you are trying to learn, then review it consistently.