General principles of SuperMemo


What is the problem SuperMemo is supposed to solve?

Have you noticed that soon after learning a new study material you remember very little of it? The less you have a chance to rehearse what you have learned, the greater the speed with which the newly acquired knowledge evaporates from your memory. It has been long known that repetition mater studiorum est. In other words, the best way towards long-term learning effect is repetition. However, you might find it quite frustrating when you have to repeat old material while your teachers or supervisors still want you to know more and more new stuff. When are you supposed to find time for both. Usually, you find a solution in-between. You spend most of your time learning new things, forgetting what you have learned earlier, and rehearsing only the material that is needed for current exams or other emergencies. The net result is disastrous! Most of your time goes to waste as you forget most of the learned knowledge. Naturally, you gain general understanding of the studied phenomena, but understanding is also based on memory traces and is equally volatile. It is only a question of time when you irreversibly lose most of your investment in learning. Is the above presented situation inevitable? After all the pressures of the day do not really let you rehearse what you have learned earlier. The educational systems throughout the world are organized in a way that penalizes those who do not master the new stuff (even if slower learning comes from the need to rehearse the previously learned material). You are pushed into nonsensical situation. You are truly forced to waste your time and ... waste your life. SuperMemo makes it possible to reduce the time necessary for repetition several times, and it shall solve some of your learning problems. It will come to rescue each time you feel bogged down with new facts or rules. Be it due to anachronic educational systems or due to the information explosion (e.g. on the Web).

How does SuperMemo solve the problem of forgetting?

Once you learn a fact, you would like to refresh your memory shortly before forgetting takes place. However, it may be very difficult to predict the moment of forgetting. Some facts are forgotten faster, other can stay in your memory for years. Luckily, there are some regularities in the process of forgetting that can help you optimize the timing of repetitions. If you learn a collection of new pieces of knowledge, let us call these pieces items, you can observe a slow but regular decline in the proportion of the items you remember. If you employ the computer to plot the forgetting curve, you can easily predict when a given proportion of items will be forgotten. If you set to constantly remember at least 90% of the material, you might try to schedule your repetition at the point when you still remember 90% of what you have learnt. This is not exactly what you would aim at. It is known that most of the material you will still remember after a period of time twice as long as the one chosen. However, there is no better way! The process of forgetting has a random nature and, at the moment of repetition, you cannot easily say which item will last longer and which will be forgotten soon. The picture becomes more complicated if you realize that different items have different difficulty and require different inter-repetition intervals. Moreover, items that have already been repeated once or twice, need much less refreshing than those that have just been learned.

Are you getting lost? Do not despair. There has been a lot of effort put into finding out the regularities in the process of learning. As a result, effective algorithms have been developed that are able to quickly determine the best possible interval for an item independent of its difficulty and the number of earlier repetitions. Those algorithms are implemented in SuperMemo. SuperMemo is a Windows program (also available on other platforms) that will manage your repetitions without much involvement on your part. It is not a painless solution, because it does not allow you to learn with no effort at all. However, it can be demonstrated in strictly scientific terms that SuperMemo helps you increase the speed of learning manifold. Indeed, it makes it possible to closely approach the maximum natural capability of the human brain to store and retain information. Over a lifetime, SuperMemo allows you to learn 10-50 times faster than by means of conventional methods, and makes it possible to reach knowledge retention of 95% or more. SuperMemo minimizes the effects of forgetting and the overall time needed for learning. This is done by scheduling repetitions of knowledge items in carefully determined intervals of time called optimal intervals. These are calculated on the basis of two contradictory criteria:

In practice, these two criteria translate into the following one:

Intervals should be as long as it is necessary for a selected small fraction of knowledge to be forgotten. This fraction, called the forgetting index, can vary from 3%, for slower and very exact learning, to 20% for blitz-learning characterized by lower knowledge retention.

If the forgetting index drops below 3%, the knowledge acquisition rate becomes unacceptably low. On the other hand, the acquisition rate peaks at the forgetting index of about 20%. Above that value, both the retention and acquisition rate decrease. Note, that one can compare traditional learning, in which repetitions are arbitrarily set in time, to time-optimized learning with the forgetting index above 50%. Such learning is not only slow, but above all, the retention of knowledge may be unacceptably low, and in consequence, instead of remembering things which are important, the student remembers only things which are easy to remember. As optimal intervals differ for particular facts or rules that are to be remembered, SuperMemo requires that the learned knowledge be split into smallest possible pieces called items. If items were to be repeated collectively, e.g., as chapters of a textbook in traditional learning, the overall optimal intervals would have to be as short as the optimal intervals for the most difficult subitem in the set. This would make learning even less effective than learning by means of classical methods. Splitting knowledge to small pieces makes it possible for SuperMemo to determine an independent repetition spacing for each of the items. Simplicity of items is perhaps even more important for cytophysiological reasons. Simple items make it possible for the right neuronal synapses to be fully stimulated at the right time. Complex items result in trains of diversified nervous impulses that result in unpredictably intricate molecular memory patterns, which make optimization of repetition spacing difficult or not possible at all. Optimum repetition spacing and simplicity of items are a formula for speed and high retention. However, the speed of learning is not the most important element of education. I t is the quality of knowledge and its representation that count most. SuperMemo allows you to learn very fast, but it is still your responsibility to properly choose the learning material prepared by yourself or by a second party.

Summary
  1. The key to effective learning is in minimizing the number of repetitions necessary to maintain knowledge in the brain.
  2. SuperMemo optimizes the process of learning by approximating optimal intervals that should separate repetitions of knowledge.
  3. The knowledge memorized by means of SuperMemo must be split into smallest possible pieces called items.
  4. Applying SuperMemo, one must not forget that the quality of learning will depend on selection of the learned material and the way it is split into items.

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