Memory

Your IQ does not really matter
Who learns faster: larks or owls?
It is harder to learn foreign languages after forty
There is a physical limitation on how much we can learn per day
We remember pictures better than words
Forgetting is a decay process that can wipe out memories for good
Memorization allows of employing associational thinking
The main myth to clear out: Easy learning in Relaxation
Maximum speed of learning is not what you really need!
Reading also involves active recall
Putting things in the same place is a good idea
To memorize names, combine mnemonic techniques with spaced repetition
Submitting to your natural sleeping rhythm seems best for learning
Herbert Simon guess on the expert memory power reflects his genius
Polyphasic sleep can hurt your learning
Poor memory is usually a self-imposed limitation
Spacing effect results from reduced potential for increasing synaptic strength
Automaticity does not correlate with the probability of forgetting
Mixing declarative and procedural learning may be good for you
Ages old techniques are still valid
Your own personalized peg-list would work best
What kind of music is best for remembering?
Why do synapses get weaker during sleep?

SuperMemo

You need repetitions to remember for ever
SuperMemo may indeed improve your memory
If you want to devour books ... you will love SuperMemo
Going to a medical school? SuperMemo is a must!
We believe SuperMemo is a must for anyone with serious plans to enter science
SuperMemo can make you more creative!
SuperMemo can lead to learning garbage
Music and incremental reading
You can easily learn 10,000 items per year
SuperMemo accelerates learning 50-fold?
Who memorized most items with SuperMemo? 
SuperMemo is vital if you are dealing with large bodies of knowledge
The effectiveness of passive review may be dismal
If you have problems with focusing on repetitions ... you may be getting nowhere 
SuperMemo discourages mindless memorization
Does not minimum information principle contradict the need for associative knowledge
Bahrick's research on Spanish vocabulary retention does not undermine SuperMemo
SuperMemo can also be used for cramming
Why is SuperMemo slow to show its strength?
8-year olds are using SuperMemo with success
SuperMemo contributes to rat race!
Can SuperMemo be used to forget things?
Questions and answers might be enough for effective learning
Does SuperMemo use short-term memory or long-term memory?
SuperMemo can help you remember things that you do not even store in SuperMemo!
Delayed repetitions in SuperMemo
Trust SuperMemo to save time
Can SuperMemo help patients with ADD (Attention Deficit Disorder)?
SuperMemo and Alzheimer's
SuperMemo and low self-esteem
Could SuperMemo become an unhealthy addiction?
SuperMemo will not help you bring things to mind without a trigger
I don't buy memory overload hypothesis in Alzheimer's
It is possible to roughly estimate the amount of time needed for learning a portion of material
Vacation may feel like "improving memory"
Is repetition the best way to remember?
Minimum information principle v.s. the length of "20 rules" article
There is no harm in "memorizing" things you already know
Users of SuperMemo 2 can be irritated!
No other software can match SuperMemo
Intervals are measured in circadian cycles
Advanced repetitions and the spacing effect
Learning to do calculations in memory
One of 1985 experiments was inconclusive
Spaced Application & Semantic Networks
Use Simulation to figure out the expected speed of learning
Memorizing instances of abstract cases is not a waste of time
Limited Postpone will not damage your learning process
First meaningful split into difficulty categories occurs at first repetition
The optimum number of repetitions will depend on numerous factors
SuperMemo should not be viewed as a cramming tool
SuperMemo does not use microspacing of repetitions
Forgetting curve for ill-formulated items is flattened
Flatter forgetting curve does not increase optimum interval
There is no remedy to interference
See also: FAQ: Learning with SuperMemo

SuperMemo Algorithm

Intervals used in SuperMemo are not optimum intervals!
Higher grades can produce shorter intervals
Even low forgetting index can produce long intervals
First repetition does not have to take place on the next day
Why isn't first repetition followed by interval=1?
Intervals are slightly randomized
The algorithm used in SuperMemo is not "fixed"
The more time you give to SuperMemo, the closer it will approximate your memory needs
SuperMemo contradicts some results reported by Tony Buzan
Grades in final drill do not affect the interval
Your response time does not matter
You can compute your retention from the forgetting index
Different intervals used in different SuperMemos
Use Simulation to estimate workload
SuperMemo ain't science! He just ad junk 
SuperMemo is better than re-wise
Mid-interval repetitions do not bias your measured forgetting index
Simulation of learning process in SuperMemo may be inaccurate 
Short-term memory requires no spaced repetition
Multitasking is not recommended in learning
Repetition category is used to update optimization matrices
First Grade vs. A-Factor graph data is kept as a collection of trailing averages

Speed-learning techniques

What is better: SuperMemo or MegaMemory?
What is better: SuperMemo or SuperLearning?
What is better: SuperMemo or Tony Buzan's mind-maps?
What is better: SuperMemo or NLP?
What is better: SuperMemo or VTrain
You can learn mind-maps with SuperMemo
Tony Buzan and SuperMemo
You can best remember mind-maps by ... splitting them to pieces
You can add a mind-map to the answer component
Memorizing mind-maps does not contradict minimum information principle
Memorizing collections such as 20x20 Multiplication Table increases mnemonic computational skills
SAFMEDS skills are useful in incremental reading
The Silva method does not seem to be based on solid science
Mega Memory and SuperMemo are complementary
Mega Memory controversy
Axon software

Other

The term "staggered learning" may sometimes be used to describe "spaced learning"
Alarm clock may hurt your learning ability
You do not need more than one nap per day
Memory "overflow" is not "fatal"
Internet addiction falls out of this site's focus

See the body of this file for more answers

(Elena and Rachel, US, Dec 12, 1997)
Question:
How is SuperMemo supposed to improve someone's memory?
Answer:
We do not claim that SuperMemo improves memory. We say that it allows you to learn fast with high retention of knowledge. The fact is that improving your memory will be a nice side effect, but this will happen not by virtue of the SuperMemo method but by virtue of intense learning. SuperMemo makes it possible to learn fast by organizing your learning process. For more see: General principles of SuperMemo

(Crizeldo  G.  Cariaso, MD, Philippines, Dec 17, 1997)
Question:
I am a medical doctor who is into resident training as of this moment.  Do you advice me to use your product if I read about 100 pages of documents and books a day and have to remember it?
Answer:
Absolutely! Read Devouring knowledge to see how you can read thousands of independent articles at the same time. If you learning from paper books, your job will be much harder. You will only be able to remember a fraction of the material. An exemplary algorithm would be:

1. divide your time to: 70% reading, 30% SuperMemo 
2. in SuperMemo time slot formulate questions in reference to the most important facts and rules you have learned from the books. Memorize  those facts. Those shall stick to your memory for ever (if you regularly run repetitions as scheduled by the program)

The sad fact is that reading 100 pages daily is really a feat, and even the mere typing in the material to SuperMemo will limit you to 20-100 questions per day (depending on time available and the speed of typing). Even this small proportion will still provide you with amazing build-up of knowledge! It is very important that you intelligently select what must and what does not have to be memorized

(Tomasz Szynalski, Poland, Oct 18, 1998)
Question:
What value of the forgetting index ensures the optimum ratio of (retention)/(time spent per day)?
Answer:

Paradoxically, the highest speed of learning can be accomplished ... without SuperMemo! In our daily life we pick up lots of facts that stay in our memory for long with few repetitions in lifetime! The problem is that these are usually not exactly the facts or rules that are critical to our goals. In other words, not the speed of acquiring new items counts but the speed of acquiring new items bearing a given content.

It is difficult to determine exactly what forgetting index brings the highest acquisition rate. Simulation experiments have consistently pointed to the value of 25-30%. You can even plot speed-vs.-forgetting graph using your own actual learning material in SuperMemo 98 using Tools : Statistics : Simulation. You will probably also arrive to similar results

As you perhaps know, SuperMemo disallows of the forgetting index above 20%. This comes from the fact that you should aim at achieving high speed of learning combined with high retention of the learned material. Setting the forgetting index above 20% would be like giving up SuperMemo altogether and coming back to remembering only that what is easy to remember. In highly interlinked material where new knowledge depends on the previously acquired knowledge, high forgetting rate can even be more harmful

Nevertheless, if you want to maximize the speed of learning with little control over what actually stays in your memory, set the forgetting index to 20%

Question:
On what basis do you ground your claim that SuperMemo increases the speed of learning from 10-50 times?
Answer:
For knowledge retention of 95%, it can be computed that the number of repetitions in an average learning lifetime (i.e. about 55 years) is roughly 50 times greater for equally spaced repetitions than for progressive repetitions (as used in SuperMemo). For repetitions with no regular spacing scheme, this number may even be greater. Moreover, the greater the required knowledge retention, the greater the increase in the knowledge acquisition rate (classical forms of learning almost never reach knowledge retention above 10%!!!). In practice, users of SuperMemo claim that it increases their speed of learning from 50% to 2000%. These values are, however, highly subjective, as they do not account for so-called intractable items, which are practically not memorizable without SuperMemo. In other words, students tend to underestimate the fact that they reach knowledge retention from 90-99%, which would hardly be achievable using any other method.

(Jerzy Duda, Poland, Oct 1, 1997)
Question:
What is the lowest age at which a child can start using SuperMemo?
Answer:
The younger the child the more difficult the entry into the learning process. However, with a dose of parental guidance, even first-graders can cope with SuperMemo. The learning process itself is simple and repetitive and the child can quickly enter regular repetitions. Definitely, SuperMemo 98 (and later) at the beginner level is much less daunting than SuperMemo 7 for the initial entry. As a documented example, 9-year-old Agata Czaplinska from Gliwice, Poland, memorized 150 new English words in 2 months working nearly on her own. In another case, 8-year-old Annalynn Clary from Monroe, Louisiana (USA) memorized Cross Country material (1673 items) in 100 days working 30 minutes per day (5 days per week)

(Elena and Rachel, US, Dec 12, 1997)
Question:
Do people with higher IQ benefit more from SuperMemo?
Answer:
People with higher IQ are more likely to find clever uses for SuperMemo and they are usually faster to grasp the principles of the program. They are also more likely to become addicted to SuperMemo as one of their most important applications. However, recent research indicates no significant correlation between IQ and any of 30 major studied learning parameters used in SuperMemo

Mixing declarative and procedural learning may be good for you (#4331)
(Robyn, Tuesday, April 26, 2005 9:11 AM)
Question:
Has an interference effect been noted between declarative and procedural learning? If I immediately follow a Spanish lesson with a martial arts lesson, will consolidation of either be adversely effected?
Answer:
Declarative and procedural learning are governed by different brain circuits and even their consolidation in sleep seems to be separated in time. For that reason, interference between both is highly unlikely. At the same time, there could be positive trophic feedback between the two (i.e. learning in one circuit may have some positive effect on another). In other words, mixing Spanish and martial arts might be a very good strategy for enhanced learning. As for the optimum sequence, it is very difficult to determine. If your martial arts training is very intense, it might better follow Spanish due to possible physical exhaustion. On the other hand, if it is modestly stimulating, it could equally well be executed before. You could also split your Spanish into two portions and execute part of it before and part of it after the training. That could prevent the overload effect (mental tiring in prolonged learning). Your best strategy for determining the learning sequence would probably be to try what seems to work best for you

Question:
Why is the first interval after which the first repetition takes place not equal in all cases?
Answer:
It is randomly modified to speed up computing its optimal value. Additionally, random dispersion of intervals around the optimum value prevents repetitions from being packed on a given day, while neighboring days have lots of room to accommodate new items.

(Tomasz Szynalski, Poland, Oct 18, 1998)
Question:
What retention can I obtain with the forgetting index set to 9%? What if I then change it to 12%?
Answer:
The formula that relates the forgetting index to the retention looks like this (source):

retention = -(forgetting index)/ln(1-(forgetting index))

If you accomplish the forgetting index of 9%, the retention will equal 95.4%. For 12%, the same figure will be 93.9%. Note that if your material is very difficult, your measured forgetting index may be higher than the requested forgetting index. This comes from the fact that SuperMemo imposes some boundary conditions on the increase of intervals. Elements that have been forgotten more than five times should be reformulated with a view to reducing their difficulty or increasing their mnemonic component.

If you initially set the forgetting index to 9% and later on increase it to 12%, you will probably start with retention of 94-95% which will later gradually decrease to 92-93% (after the change)

(David Mckenzie, New Zealand, Apr 8, 1998)
Question:
Why does not the first repetition after forgetting occur the next day after the unsuccessful repetition (this is advised by Tony Buzan and others)?
Answer:
In SuperMemo, the length of the first interval is computed from the forgetting curve plotted in the course of repetitions. This is to make sure that a defined proportion of items is remembered (usually 80-97%). This proportion is programmed by means of the forgetting index. Depending on the forgetting index, the length of the first interval may range from 1 to 20 days, and is not set arbitrarily. It is computed from the record of repetitions and determined by the desired forgetting index (requested forgetting index is the proportion of items that are not remembered at repetitions). While Buzan’s recommendation is valid in many cases, you should not forget that SuperMemo computes intervals with a high degree of accuracy that cannot otherwise be easily achieved

(Constantin Ilieu, Bulgaria, 1993)
Question:
In your materials I found a contradiction. On one hand you claim that once learned knowledge is constantly maintained in the student's memory, on the other you say that after ceasing repetitions, I will gradually forget what I have learnt. Which is true?
Answer:
Both facts are true. The term maintained is understood as kept in memory by means of repetitions, not as remains in memory for ever

(Manfred Kremer, Germany, Sep 7, 1998)
Question:
I noticed that frequently I get Optimum Interval in Element Data window shorter than the last interval displayed as Interval. Is it a bug in SuperMemo?
Answer:
No. If your forgetting index is very low, e.g. 3%, SuperMemo will often conclude that you will stand 97% chance of remembering a given element only if your next interval is shorter than the presently used one. In such cases, it will not accept the new value and the new interval will be at least 5% longer than the previous interval. Please note that the forgetting index equal 3% should only be used for selected high-priority items. Keeping the forgetting index at this level throughout the collection will make repetitions annoying frequent and ineffective

(Ryszard Siwczyk, Poland, Nov 4, 1997), Poland, Nov 4, 1997)
Question:
Does the response time at repetitions influence the next interval?
Answer:
No. Repetition timer is only used to compute the average response time and Workload.

Polyphasic sleep can hurt your learning
(Mariusz Zmuda, Poland, March 22, 2000)
Question:
Is it true that it is better to get shorter sleep in the night and then take a few naps during the day?
Answer:
This approach is not likely to benefit your health or learning. Most of all, you should not artificially shorten the night sleep! As for the naps, in healthy adults there is only one major trough in alertness during the day at siesta time. Taking more than one nap is not likely to be needed. Experts on insomnia argue against naps as these may keep people up at night. If your nap lasts only 5-45 minutes and does not affect your ability to fall asleep in the night, it will help you stay more alert in the evening hours. See: The cruel myth of polyphasic sleep and Good sleep for good learning

(Grzegorz Malewski, Poland, Dec 10, 1997)
Question:
Do grades at final drill affect the learning process?
Answer:
No. They are only used to eliminate items from the final drill queue.

(Spud Science, USA, Feb 14, 1998)
Question:
What is the best (most effective) way to set up a new series of question and answer pairs in SuperMemo?
Answer:
See: 20 rules of formulating knowledge. See also: SuperMemo Decalog. For a more academic reading in the subject you can have a look at Knowledge Structuring and Representation...

(Matt Cassidy, New Zealand, Sep 11, 1997)
Question:
Is it possible that with forgetting index equal to 3% I get the first interval equal to 6 days?
Answer:
Yes. Especially if the material you work with is relatively easy. You should also remember about random dispersion of intervals. In isolated cases, dispersion might produce intervals substantially longer (or shorter) than the optimum interval. For more read about SuperMemo Algorithm

(Jake White, USA, May 14, 1997)
Question:
Should not final drill continue keeping a queue of no less than 10 newly learned words in order to make sure that when repeated again and again they will really be imprinted well in short-term memory.
Answer:
This solution may indeed eliminate contextual dependency in final drill (remembering items only because of having them in a given context); however, this would involve lots of extra repetitions that would contradict the principle of SuperMemo: maximum effect at minimum time. Additionally, the learner would risk activating the spacing effect, i.e. reducing the probability of recall as a result of excessive repetition! The best solution to contextual dependency is (1) random shuffling of final drill queue with Tools : Randomize : Drill and (2) concentration (not grading well items that were remembered only due to appearing in a given context).

Question:
I have heard that baroque music is the best for improving memory; particularly Bach and Vivaldi. Does it also work in association with SuperMemo?
Answer:
The claim that any particular kind of music is best for memory is unlikely to be true. Indeed, music can have powerful impact on our emotions and, consequently, on remembering. It has been found that it is similar in effects to caffeine. However, a study that measures impact of a particular kind of music on recall in a group of people can be compared to trying to find the optimum size of a shoe for an average citizen. Depending on the musical education of an individual, the same kind of music may bring a variety of emotion from relaxation, through agitation to aggression. While Four Seasons may have a positive impact on the mind of majority of the population, the best bet would be that everyone should stick with the music he or she likes. Be it punk or funk. The truth is that all that is good for the mind and health is good for remembering.

(Miss E216, US, Nov 25, 1997)
Question:
We are 7-th graders and work on a project related to memory. We have a question to Dr Wozniak: "Why do we better remember pictures than word combinations?"
Answer:
In the course of evolution, humans practiced visual memory a lot. They did not deal much with math or abstractions. That is why there are parts of our brain built specially to serve visual memory. As you know, evolution gives better adapted individuals a better chance for survival. Those who could remember better, e.g. shape of the prey or enemy, could survive better, and pass their "good" genes to the next generation. Calculating a differential was not needed in apes or early humans. That is why evolution did not built a specialized calculator into our brain. It has, however, built a calculator for processing visual data. You "type in" the picture, and get a short answer: "danger!" or "food!". Those simple signals are easier to remember than ... streams of bits of a complex image. Evolution and memory are fun, aren't they.

Question:
Can I use SuperMemo to memorize mind maps?
Answer:
Yes. You can build mind maps directly in SuperMemo; however, it is easier to import them from specialized mind map software (e.g. MindMan). You can include MindMap objects with the OLE component or you can simply import them as graphics (as BMP or GIF files).

For example, import your mind map as graphics to an image component and check Answer on the image component menu. Add a text component, e.g. "What is the structure of mind map X?".
During repetitions grade yourself less than Pass (3) each time your forget any part of the mind map! Do not forget that you should reinforce "weak links" in the mind map with separately formulated items of simple question-answer or question-picture form. Each time you forget part of the mind map, see if you have reinforced the forgotten links in separate items!

(Julien Seetharamdoo, UK, Jan 3, 1997)
Question:
I would like to know how to memorise mind maps?
Answer:
The best method is to split the mind-map into simple individual pieces and memorize these pieces separately! The pieces must be chosen in such a way that ensuring that you remember all of them you can guarantee that you can recall the whole map. You can find more information about this in knowledge structuring in repetition spacing

(Julien Seetharamdoo, UK, Feb 19, 1998)
Question:
I am trying to use SuperMemo 8 to learn mind maps created using Mind Manager. I have imported the mind maps as BMP files to the image registry but haven't been able to append them as answers to questions. How do I do this?
Answer:
It is faster to import files directly to image components:

1. Create an image component in the element window
2. Use Import file to import the BMP file (right click to open the pop-up menu with Import file).
3. Check Answer on the component menu to make sure that the image is not visible at question time.

NB: If you already have images in the registry, you can use Link Registry Member on the image component menu (instead of Import file).

Question:
Isn't memorizing mind maps in opposition to the minimum information principle?
Answer:
No. Minimum information principle should not be interpreted as minimum information on the screen, or minimum number of bytes to represent the item. It should be interpreted in terms of information that has to be stored in your memory. If you produce and item that links the image of a horse and a cow, the association is very simple. No mater how intricate the pictures of the horse and the cow are. The essence of mind maps is that they are easy to remember, i.e. if well-designed, they comply excellently with the minimum information principle.

Question:
Which learning method is more effective: traditional SuperMemo with questions and answers, or the new hypermedia SuperMemo with videos, games, puzzles, and tests?
Answer:
Simple questions and answers are extremely effective and easy to create; however, some users find classic SuperMemo too boring. If the psychological factor plays a part, the variety provided by SuperMemo 8 may substantially add to the effectiveness of learning. The answer to the question will depend on the application domain and the mentality of the student.

(Elena and Rachel, US, Dec 12, 1997)
Question:
Does SuperMemo improve short-term memory or long-term memory?
Answer:
SuperMemo builds up long-term memory but helps you increase your mnemonic skills that will result in the impression that your short-term memory works better.
You can also look at this like that: SuperMemo loads knowledge to short-term memory and this is transferred to long-term memory. The effect on long-term memory is stable but the speed of putting things into short-term memory may increase due to training. Short-term memory improvement comes slowly with training, but long-term memory build-up comes immediately upon employing SuperMemo!

One of 1985 experiments was inconclusive
(Tomasz P. Szynalski, Saturday, August 04, 2001 1:33 PM)
Question:
I see that one of early experiments showed that constant 18-day intervals were better than increasing intervals. So how does this prove the validity of SuperMemo?
Answer:
This 1985 experiment does not prove validity of SuperMemo. Nor does it disprove it. In that respect, it is simply inconclusive. The experiment was an attempt to "guess" optimum increase in intervals and the guess appeared wrong. If the underlying hypothesis was that increasing intervals are always better than equally distributed intervals, then this experiment proved that hypothesis wrong. Obviously, if equal intervals are short enough or the increase in the length of intervals is too fast, equal-interval schedule may appear superior. This is why, in the long run, we need to use a computer to optimally adjust the repetition schedule to the defined level of knowledge retention

(Prof. Witold Abramowicz, Poland, Feb 1993)
Question:
Does the minimum information principle not stand in conflict with the ages old rule that the learned knowledge should be highly associative in nature?
Answer:
No. The minimum information principles concerns the representation of knowledge in SuperMemo databases, not in the student's memory, and it does not prevent great advantages coming from proper structuring of the learned material. In the optimum situation, the student should first construct a cohesive model of the learned subject, and only then, apply SuperMemo to make sure that the learned knowledge is sustained in memory as a whole. The knowledge may be highly associative, but strictly targeted neural stimulation, achieved by means of granular representation of knowledge in SuperMemo, is necessary to effectively induce molecular processes responsible for memory formation. Indeed SuperMemo has been conceived in such a was so as to make it easier to formulate knowledge in a structured way (topics) and later learn it in a way typical for SuperMemo (items). See also: Topics vs items

(Anatolyi Lipatov, Ukraine, Jul 12, 1998)
Question:
I am using Advanced English to enhance my English and business English. Now I am registering for CFA examination (that is Chartered Financial Analyst program of Association of Investment Management and Research). There are several organizations developing and distributing methodological stuff for preparing to the exam. A lot of things should be memorized for passing the exam. What do you think the best way to fit SuperMemo for memorization and what approach should I use to prepare my own knowledge base for memorizing the material. Is special programming knowledge needed for it?
Answer:
No specialist knowledge is needed to prepare simple learning material collection in SuperMemo. With Alt+A (i.e. Add new) you get 90% of functionality! All advanced editing options can be worked around by an appropriate questions-and-answer approach. Perhaps it would be useful yet to learn how to add images to your items (see help for details). To learn more about effectively structuring knowledge in SuperMemo you might want to read 20 Rules of Formulating Knowledge and Knowledge Structuring and Representation; however, nothing works better as learning on one's own mistakes in formulating knowledge for learning with SuperMemo

(Pawel Dzierwa, Poland, June 3, 1997)
Question:
Personal question to Dr Wozniak: If you did not have SuperMemo at hand, which competitive product would you use?
Answer:
I would probably pick one of the programs that most closely follow the SuperMemo paradigm, e.g. Edukom or PowerMemo. Only later would I choose from better known products that are less focused on spaced repetition such as Langmaster or YDP's Collins Dictionary. However, as a software developer involved in the design and implementation of SuperMemo since 1987, I would rather opt for implementing the program from scratch. Back in 1987, the first version was written in 16 evenings. I would have to give up all the bells and whistles, but it is the core that matters most. And it would be most difficult to give up the control over what new options might yet be implemented

(Colin Quiney, Canada, Jan 22, 1998)
Question:
Do you think SuperMemo can be beneficial in patients with ADD (Attention Deficit Disorder)?
Answer:
User's ability to focus on repetitions is one of pre-conditions of success with SuperMemo. Seemingly, this would make ADD patients poor SuperMemo learners. Perhaps the report submitted by Maarten Mols from Holland sheds some different light on the issue: SuperMemo in a school for special education.

SuperMemo and Alzheimer's
(Maria Jonas, South Africa, Dec 2000)
Question:
Can SuperMemo be used in the treatment of Alzheimer's?
Answer:
Except for inconclusive anecdotal data, there has been no study of SuperMemo in Alzheimer's. See also: Can too much learning lead to Alzherimer's?

Question:
Tony Buzan claims that 75% of information is lost if not reviewed in 24 hours. Does it not defeat the validity of SuperMemo in which the first interval is often longer than a week?
Answer:
No. Buzan's claim may refer to textbook knowledge or complex knowledge structures (e.g. large mind maps). However, it does not seem accurate in reference to simple well-structured material in the light of results obtained with SuperMemo. In SuperMemo, if the student chooses the retention of 95%, the typical value of the first interval falls in the range 2-5 days depending on the student and the difficulty of the learned material. For retention 25%, the same interval might be as long as one month, though it cannot be verified experimentally with SuperMemo which limits the range of the forgetting index from 3-20%, which implies the overall retention in the range of 89-99%. For more see: Theoretical background of SuperMemo

(William McGhee, Jun 22, 1998)
Question:
Could SuperMemo be used to extinguish behaviours as well as reinforce them?
Answer:
Forgetting is a molecular process that cannot easily be induced by natural methods. The more so, there are no sensitive methods to induce selective forgetting, though lesion to some parts of the cerebral cortex may produce roughly localized amnesia. However, there is a component of forgetting that may be influenced. This component is interference. Whenever we learn new things, they always interfere with previously learned material. The interference may enhance some of memories while obliterating others. This fact can be used to employ SuperMemo in forgetting, by formulating and memorizing a large number of contradictory items that strongly interfere with remembered facts that are to be forgotten. For example, if you learn the meaning of the word "indict" and you want to later forget it, you might try to learn words like "indite" or some meaningless like "dictin", "incid", "endict", etc. However, you should not expect the effectiveness of such a procedure to be anything but disappointing.

Question:
I used SuperMemo 2 shareware, and was accustomed to repeating forgotten items on the next day. It is very irritating that in SuperMemo for Windows I do not have this possibility
Answer:
SuperMemo will schedule forgotten items in intervals that are determined by the forgetting index. The greatest increase in the speed of learning in newer versions of SuperMemo as compared with SuperMemo 2 resulted from substantially increasing the length of the first interval. The student may be left with the feeling that he is likely to forget the item again if it is not repeated on the next day. Statistically, however, he will forget no more than the proportion defined by the forgetting index (specified in Tools : Options : Learning : Forgetting index). By reducing the forgetting index to less than 5%, the length of the first interval is likely to drop to 1-2 days in most cases. Moreover, if you are particular about repeating a given item on the next day, you can choose Ctrl+M to commit or recommit an item with a selected first interval

Question:
I have an exam for a driver's license in 2 weeks. How can I best memorize the Traffic Regulations collection for SuperMemo? How can I increase the frequency of repetitions?
Answer:
Although SuperMemo is not a cramming tool, and it would be much safer to start 2-3 months before the exam, the following shall work pretty well: (1) Set Tools : Options : Learning : Forgetting index at 3%. (2) When memorizing difficult items, choose Ctrl+M and provide the first interval value equal to one day. (3) Memorize the collection in equal portions in the period spanning from today to 2-4 days before the exam. Use Tools : Random review intensely over the last 2-4 days

(Shaun Hoffland, UK, Oct 22, 1998)
Question:
Do you have statistics on what is the average number of items an average user has to repeat per day? What is the greatest number of memorized items?
Answer:
The best results oscillate around 60,000 items memorized overall, and 10,000 memorized within 4-5 months. Most users memorize 1000-10,000 items per year. Please read SuperMemo User Survey (esp. section Using SuperMemo)

(Scot Prohaska, USA, Oct 29, 1998)
Question:
I am going back to medical school after a 10-year break. I look for tools to improve my brain skills. Is SuperMemo a product for me?
Answer:
That's your lucky day! SuperMemo is ideally suited for enhancing your ability to learn new stuff and make sure it stays in your memory for good. Learning medical sciences with SuperMemo comes second in popularity to learning English! Recommended reading: Six steps to excellent memory

(Tomasz Szynalski, Poland, Oct 18, 1998)
Question:
When first versions of SuperMemo were released, how could SuperMemo predict intervals that were many years long if it had only been researched for a couple of years? I read that the first version was released after just 3-4 years of research on the length of intervals.
Answer:
The first experiments in reference to the length of optimum interval resulted in conclusions that made it possible to predict the most likely length of successive inter-repetition intervals without actually measuring retention beyond weeks! In short, it could be illustrated with the following reasoning, if the first months of research yielded the following optimum intervals: 1, 2, 4, 8, 16 and 32 days, you could with confidence hope that the successive intervals would increase by a factor of two. To better understand what reasoning lead to the first formulation of SuperMemo read: First experiments: 1982-1985

(Tomasz Szynalski, Poland, Oct 18, 1998)
Question:
What retention can I obtain with the forgetting index set to 9%? What if I then change it to 12%?
Answer:
The formula that relates the forgetting index to the retention looks like this (source):

retention = -(forgetting index)/ln(1-(forgetting index))

If you accomplish the forgetting index of 9%, the retention will equal 95.4%. For 12%, the same figure will be 93.9%. Note that if your material is very difficult, your measured forgetting index may be higher than the requested forgetting index. This comes from the fact that SuperMemo imposes some boundary conditions on the increase of intervals. Elements that have been forgotten more than five times should be reformulated with a view to reducing their difficulty or increasing their mnemonic component.

If you initially set the forgetting index to 9% and later on increase it to 12%, you will probably start with retention of 94-95% which will later gradually decrease to 92-93% (after the change)

(Tomasz Szynalski, Poland, Oct 18, 1998)
Question:
What value of the forgetting index ensures the optimum ratio of (retention)/(time spent per day)?
Answer:
Paradoxically, the highest speed of learning can be accomplished ... without SuperMemo! In our daily life we pick up lots of facts that stay in our memory for long with few repetitions in lifetime! The problem is that these are usually not exactly the facts or rules that are critical to our goals. In other words, not the speed of acquiring new items counts but the speed of acquiring new items bearing a given content.

It is difficult to determine exactly what forgetting index brings the highest acquisition rate. Simulation experiments have consistently pointed to the value of 25-30%. You can even plot speed-vs.-forgetting graph using your own actual learning material in SuperMemo 98 using Tools : Statistics : Simulation. You will probably also arrive to similar results

As you perhaps know, SuperMemo disallows of the forgetting index above 20%. This comes from the fact that you should aim at achieving high speed of learning combined with high retention of the learned material. Setting the forgetting index above 20% would be like giving up SuperMemo altogether and coming back to remembering only that what is easy to remember. In highly interlinked material where new knowledge depends on the previously acquired knowledge, high forgetting rate can even be more harmful

Nevertheless, if you want to maximize the speed of learning with little control over what actually stays in your memory, set the forgetting index to 20%

(Robert Szumilo, Poland, Jan 3, 1999)
Question:
What is the optimum approach to making repetitions with SuperMemo: one long session or a few smaller sessions (e.g. main repetitions in the morning and the final drill in the evening)?
Answer:
For psychological reasons, the quality of learning should increase substantially when working in separate sessions, esp. if the number of repetitions surpasses 100 per day. Additionally, a break before final drill is useful due to the spacing effect. The danger of this approach is ... you can easily drive yourself into a situation in which you will spend excessive proportion of your day on repetitions (in the future when your schedule changes you might have problems with keeping up with your present pace)

(Tony D'Angelo, USA, Feb 3, 1999)
Question:
I am a management consultant who uses professional development programs from a company called Resource Associates Corporation. These programs are based upon spaced repetition learning. In their literature they cite an unnamed study that suggests that people will generally only retain 2% of information they are exposed to in a one time event after 2 weeks. In contrast they suggest that at least 65% of information delivered over 5 consecutive days may be retained for 15 years to life. Can you confirm those claims?
Answer:
If you look at the graphs generated by SuperMemo during the learning process, you will notice that the 2% figure might be true depending on how the material has been presented and its difficulty. However, the claim that 65% of knowledge can be retained for 15 years as a result of five-day exposure must be false in the same light. Even if we consider perfectly formulated knowledge (i.e. knowledge characterized by the highest possible A-Factor), you might need to space the quoted five exposures in the period of 2-3 years to make the 65% figure realistic. If the quoted figures were accurate, you would probably never need to use SuperMemo! For more details on the speed of learning, see Theoretical aspects of SuperMemo

(Lawrence A. MacDonald, USA, Feb 16, 1999)
Question:
From your experience, and I know it is different with different people, how many repetitions (how far out on the scale in the future) does one need to make to have mastered in information, and what is the standard deviation for that number?
Answer:
There is no point when you can say the material is remembered for ever! Even after 20 years of repetitions there is a slight risk of forgetting. If you want to always remember a piece of information with a defined degree of probability, you should proceed with your repetition till your last day on this planet

(Lawrence A. MacDonald, USA, Feb 16, 1999)
Question:
What is the result on scheduling in the future when you add a question every day? At what point does your future schedule become vastly over booked?
Answer:
The beautiful thing about SuperMemo is that overbooking never happens! Your question and worry is typical for those who begin their work with SuperMemo. Please have a look at simulation experiments that show that the learning curve, in the long perspective, is nearly linear, i.e. it does not bend as a result of "overbooking"! In practice, you will be able to notice the decline in the speed of learning for no more than a year. Later the slowdown is minimum and entirely imperceptible! The mathematical explanation of this is quite complex. The measurements show that you spend 50% of time on just 2.5% of the material! Imagine then that the memorized material quickly reaches high intervals and disappears from view. You just constantly struggle with newly memorized items and items that you find difficult to remember

(Vit Usela, Czech Republic, Nov 2, 1999)
Question:
What do you think of so called memory-enhancing smartdrugs: Piracetamum, GABA, Vinpocetin, Takrin, Diapid, Vasopressin, Fipexid, Deprenyl, Hydergin, etc.?
Answer:
We do not take an official stand on memory enhancing drugs. Please consult other sources. Note the following though:

1. Forgetting has an important biological function and all attempts to prevent it by non-selective means are likely to result in information confusion described in some clinical case studies in psychiatry
2. Some of the drugs listed play an important physiological function and may be of value in learning for reasons other than memory enhancement. In this context you could always best consult your physician
3. Simple health-boosting factors such as exercise, healthy diet, sufficient amount of sleep and stress-management are likely to bring more benefit to your learning that all listed drugs taken together

(Tomasz Szkopek, Poland, Feb 25, 1999)
Question:
Does using SuperMemo increase the capacity of the human brain for learning with traditional methods?
Answer:
SuperMemo is likely to strengthen your mnemonic capacity. It is does not include any specific options for that purpose, it simply acts as a training tool via repetition. Your mnemonic techniques will develop subconsciously as a result of training the same way like muscles grow as a result of lifting weights. However, this should not be treated as a substitute for a course in mnemonic techniques. If you have not heard about mind maps and peg lists, you might want to visit sites listed in the links section (e.g. Buzan site).
Secondly, recent research shows that the brain continues growing new neurons and new synapses even at a very advanced age. This process is dramatically enhanced by rich environment and intellectual stimulation. It is possible that a 40-minute session with SuperMemo also acts as a good stimulant of these growth and development processes (as much as any challenging intellectual activity)

(Vit Usela, Czech Republic, Nov 2, 1999)
Question:
You advise to merge all SuperMemo collections in one. Does it not contradict the principle of avoiding knowledge interference?
Answer:
No. The same items are not likely to interfere more with each other once they are put in the same collection and repeated one after the other. Indeed, this may even help resolve the interference by means of techniques described in 20 rules of formulating knowledge. For those who learn material related to various branches of knowledge, an interdisciplinary mixture of repetitions often generates unexpected associations that can be a goldmine of ideas in your professional field. This is the simplest illustration of the fact that SuperMemo can make you more creative!

Question:
It is well know that people can be divided into late sleepers, owls, and early sleepers, larks. Has there been any research to indicate what sleeping type has better memory?  
Answer:
The conviction that people are inherently prone to be either larks or owls is wrong. Most owls would claim it is virtually impossible to shift to earlier hours of sleeps while larks just cannot keep their eyes open late in the evening. However, the main reason for this differentiation is not physiology but lifestyle. The stereotype is reinforced by the fact that it is indeed very difficult to shift the sleeping rhythm even by a few hours. If you try to force an owl to start getting up at 5 am, you will expose it to immense mental and physical torture that may quickly result in serious health consequences! However, with the right approach, an owl can gradually be shifted into an early riser mode! The shift must be gradual as no magic force can instantly override the body's internal clock. The main reason why owls are owls is that they tend to excitedly spend their time over a book, movie, or computer game till early hours of the morning. They enjoy the quiet of the night when they can pursue their passion. Subconsciously, they try to get as much of the night time for their pursuits as possible. Were it not for school obligations, family or a job, owls might easily shift to going to sleep at sunrise or later. This is why an owl will find it easy to go to sleep later and later, while it will be nearly impossible to gradually shift the sleeping rhythm in the opposite direction: it is 20-30 minutes earlier each day. For an owl to become a lark, the shift should go in the opposite direction. If an owl goes to sleep 1 hour later each day, soon it will cycle to sleep through the day and finally start getting up as early as 1-2 am. An owl can comfortably stick to such a cycle for quite long until its natural tendency to go to sleep later each day will not ruin it. Moreover, people isolated from external stimuli tend to fall into cycles slightly longer than 24 hours which also explain why it is easier to prolong the day rather than to shorten the night.
The above facts illustrate that there are no underlying physiological reasons for being of a particular sleeping type. The reasons are in the lifestyle and personality (which are both strongly connected). Owls may show lots of excitement for learning as this excitement is the main factor that makes them owls. On the other hand, larks can make better use of early morning hours where they can study in quiet at the time when their brains are most refreshed. The formula for better learning would then probably be to sleep in a way that brings maximum refreshment, i.e. without paying much attention to the actual sleeping hours

(Mariusz Zmuda, Poland, March 22, 2000)
Question:
I sleep seven hours per day and wake up with an alarm clock. I read that using the alarm clock may negatively affect learning. Is it true?
Answer:
There is a significant body of evidence that the you will get the best results in learning if you have your sleep out. Many individuals need eight or more hours of sleep. It is difficult to predict how damaging the alarm clock can be in your case. It will mostly depend on how much sleep your body actually needs

Question: 
Can SuperMemo help remember things that are not stored in SuperMemo?
Answer: 
Yes. To a limited degree. There are three ways in which this is or may be happening: 

1. knowledge which is closely associated with facts and rules you keep in SuperMemo will often be reinforced even if it is not actually stored in the program. For example, if you memorize a few items about John D. Rockefeller without including his photograph and later see his face on TV, it may happen that you will indefinitely be able to recognize his face. You will notice that Rockefeller's face will subconsciously be brought to your imagination at each repetition related to his life 
2. SuperMemo will enhance your mnemonic skills and help you improve your short-term memory. This is the case not only with SuperMemo but also with all other forms of learning 
3. Similarly, learning is likely to have a positive trophic effect on your brain tissue. This should also enhance your general intellectual performance. The scope of this effect is difficult to quantify but it has been proved in a number of experiments that rodents bred in enriched environment grow more neurons, learn faster and live longer

(Ben Lister, Apr 5, 2000)(comment placed at PalmGear in reference to SuperMemo for Palm Pilot)
Comment:
[…] this "scientific study" thing [in reference to SuperMemo], that's a bunch of advertisement junk. It's not science that they use, but simple variable calculations. The program detects the number of times you have gotten something right or wrong and then uses this number to decide when it should next be on a test, like a priority list
Rejoinder:
Ben Lister's observations were surprisingly derived from SuperMemo for Palm Pilot, which reveals little of its internally used optimization procedures (which are slightly simplified as compared with the Windows version). The timing of repetitions may remotely be correlated with the number of bad grades, but is actually derived from the currently estimated so-called memory stability (which reflects how quickly memory traces volatilize) and knowledge difficulty (which reflects the increase in stability as a result of a repetition). Consequently, items with a large number of memory lapses can be repeated in longer intervals than items with fewer memory lapses (unlike it is claimed by Ben Lister). SuperMemo does not use a priority list in scheduling repetitions. The scheduling algorithm does not consider the relationship between items but their reference to time, their difficulty and the history of repetitions. For example, if repetitions were to be delayed, the "priorities" would change. So would the scheduling. The central point of the algorithm is based on plotting the forgetting curve and predicting the optimum timing of the next repetition. The greatest merit of SuperMemo is in fine-tuning the algorithm so that it can adapt to individual skills and knowledge in shortest possible time. No algorithm running in abstraction from the actual forgetting curve stands a chance to compete with SuperMemo in its efficiency (this includes neural algorithms that indirectly will predict the probability of forgetting)

(M.R.W., Poland, March 24, 2000)
Question:
SuperMemo does not seem to provide enough support for those who cannot afford to spend their time daily on regular repetitions. The daily regimen may discourage a large number of potential users. Sometimes one would like to double the effort. On other occasions, one might not feel like working with the program at all. For example, I could never convince my father to use SuperMemo. When he comes back from work, he is often too tired to watch TV, let alone make repetitions. Do you plan to include special tools that would make it possible to learn only on weekends or exclude certain days of the week?
Answer:
Weekly calendar of repetitions is in consideration; however, this option adds complexity without actually providing much learning benefit. It may actually appear harmful:

1. daily repetition regimen comes from the properties of human memory, not from the design of SuperMemo. All delays in making repetitions are unwelcome and should be discouraged
2. we have documented dozens of cases in which users regularly abused Tools : Mercy and ultimately concluded that SuperMemo does not work! Those users blamed SuperMemo, not their own lack of regularity! We have even removed an infamous tool from SuperMemo 7 called Wipe that made it possible to reduce workload by removing the most difficult items. This tool, despite warnings, have ruined the learning process of many users who used it as the shortest way to spending less time on repetitions
3. most of users who prefer SuperMemo for Palm Pilot as opposed to SuperMemo for Windows list its simplicity as an advantage second only to portability. Despite its high satisfaction ratings, the main complaint about SuperMemo for Windows is its complexity and featuritis (i.e. too many features)
4. there is a very simple way towards freeing the user from the daily regimen of repetitions: hiding the statistics. With statistics hidden, the student can delay repetitions without the sense of guilt. He or she can also triple the workload on good days. However, experiments show that in such cases, users add much more learning material that they are able to repeat. This results in significant repetition delays, and a dramatic increase in forgetting. Consequently, the learning process becomes similar to traditional learning, learning results unimpressive and a drop-out rate very high
5. users who are truly unable to spend their time on learning on certain days are encouraged to use Postpone

(Tomasz Strzelczyk, Poland, Jan 31, 2001)
Question:
I would like to invest in a Langmaster course of English. How would you convince me that SuperMemo is superior to the rewise method? 
Answer:
English courses by Dr Lang have a very good reputation for quality and they can be recommended independent of the question on the efficiency of the re-wise method. You could invest in a Langmaster course that best suits your needs and boost your vocabulary with SuperMemo and Advanced English. Alternatively, you could use stand-alone SuperMemo for learning the material from the Langmaster course. As the for re-wise method (developed in Czech Republic around 1994), its principles are similar to SuperMemo; however, we have no doubts as to the superiority of SuperMemo technology that encompasses far more than the repetition scheduling. We have not tested re-wise extensively, but our customers who also use Langmaster CD-ROM titles, unanimously confirm that they prefer to keep their learning material in SuperMemo. Combining Langmaster courses with stand-alone SuperMemo or with Advanced English would probably be the recommended course of action

(Terje A. Tonsberg, Kuwait, Jan 13, 2001)
Question:
I received seemingly wrong results when using Tools : Simulation in SuperMemo. I got the minimum speed of learning for the forgetting index of 8%. Once I reduced the forgetting index to 5% and further to 3%, the expected speed of learning increased substantially!
Answer:
Your observation is accurate. Indeed, there is a discrepancy between the simulation procedure and SuperMemo Algorithm used in computing the optimum schedule of repetitions. In many texts about SuperMemo you will find that SuperMemo ensures the retention programmed with the forgetting index on the assumption there is no delay in repetitions. This is however imprecise. To prevent clogging up the learning process, Algorithm SM-8 makes an assumption for grades Pass and above (3-5) that the interval must increase by at least one day (i.e. it cannot decrease nor can it stay the same). For low values of the forgetting index and for difficult learning material this assumption actually means a significant departure from the expected retention level. Unfortunately, the simulation procedure does not take this fact into the account, and it does not attempt to correct the forgetting rate which increases as a result of the rigid limitation imposed on the increase in intervals. Consequently, for a low value of the requested forgetting index, the measured forgetting index may be higher than the one assumed for the simulation purposes. This will naturally produce skewed simulation results: repetitions scheduled late by Algorithm SM-8 will still produce high retention as programmed by the forgetting index fed into the simulation input data. For that reason, simulation may be inaccurate for a low forgetting index if your learning material is difficult.
In the future, we hope to make it possible to adjust retention for the departure of Algorithm SM-8 from the optimum repetition schedule, as well as to make it possible to simulate repetitions at intervals that fully comply with the forgetting index. That latter option would naturally slow down the learning process even further

(Lisa Arcella, Women's World magazine, Jan 26, 2001)
Question:
What techniques can you use to remember someone's name after you meet them? For example, some sort of word-association; if the person's name is Smith, associating a blacksmith with them might help. If you could give me two or three tips for our readers that would be really helpful
Answer:
Associating Smith with blacksmith and providing a mental image of Smith hammering his colleagues at work is likely to leave a strong memory imprint (the more gruesome or shocking the association, the better it works). The solutions range from low-tech and less efficient to high-tech and "memory-leak-proof": 

• mnemonic techniques - this is how the problem of forgetting used to be solved for centuries 
• spaced repetition - this is the method that eliminates forgetting in the most efficient way (with efficiency limited only by inherent properties of human memory)

Mnemonic techniques: The Smith-blacksmith approach falls into the category of mnemonic techniques, which use the power of the visual cortex of the brain to represent memories that humans are poor at remembering (e.g. complex numbers). We easily remember images and can often recognize faces after very long intervals without repetition in the meantime. However, an intelligent person will often find it difficult to recall seven consecutive digits presented one after another. Humans are inherently poor at numbers! With mnemonic training, the same person may quickly arrive at remembering sequences of 50 digits, cards, or objects. The Guinness Record drives this to unimaginable heights (thousands of digits or playing cards) -- far surpassing what we need in our daily lives. One of the most useful techniques, for remembering numbers (e.g. phone numbers) is the so-called peg list. If you memorize 100 so-called pegs that associate numbers with pictures (e.g. one is tree, two is a switch, three is a tripod, etc.), you will quickly learn to "see" numbers as "scenes". For example, 911 might be a cat ("cat has nine lives") stretched between two trees (assuming tree is one). Memorizing 100 pegs is a substantial effort and not many will want to undertake it. However, remembering a 10-digit number can then be reduced to remembering a 5-event sequence (e.g. my grandmother is chasing the postman who hides in a manhole and is eaten by a giant rat). Such memories tend to be manifold easier to retain. If you need to remember more than 30 numbers, the investment in memorizing the peg list will pay back. Beyond 50 (e.g. your personal phone book), peg-list is a pure saving.

Spaced repetition: The above mnemonic approach converts "difficult memories" to "easy memories" and is a subject of many books and self-improvement tapes worldwide. However, there is a substantial flaw. "Easier memories" are also subject to forgetting! They tend to be lost at a slower pace but they do get lost in the end. Forgetting also affects the peg-list if it is not rehearsed often enough. In other words, we cannot remember without a review/repetition. Spaced repetition can rationalize and simplify the review of study material, and ensure nearly perfect recall. This may not be as easy to present to your readers as the Smith-blacksmith association, however. The major drawbacks of spaced repetition are:

• for a quality application, you need a computer and software called SuperMemo (from Super Memory); also available as freeware
• for top-quality use of SuperMemo (call it "power SuperMemo"), a number of skills are needed, which are considered "complex" by non-technical people (see: Devouring knowledge)

Memory "overflow" is not "fatal"
(Chris Houser, Japan, Sun, Feb 06, 2000 12:13)
Question:
One some website related to SuperMemo I found that without forgetting "the brain would fill up ... with ... fatal results". This sounds quite silly. Does research support this?
Answer:
No. This statement is unfortunate. We are unable to control all what is being written about SuperMemo. The corrected statement might be: Forgetting is needed to clean up room for new memories in the limited space of the human brain. For example, neocortical representations cannot be reconstructed by the hippocampus due to the limited size of its network; hence the constant flow of memories. The reports of patient confusion in cases of reduced forgetting are sporadic and difficult to verify. Genetically engineered mice that exhibit reduced forgetting rate have actually been shown to outsmart normal mice in tasks such as navigating a maze

(Jason Roos, USA, Mar 27, 2001)
Question:
When I need to memorize a bunch information, I make flashcards. My gut is usually a good indicator of when I need to go through them again. It's surprising to me there seems to be so much scientific study behind SuperMemo. (full text below)
Answer:
If you try SuperMemo for some time, you will notice that it is quite liberating to let the computer do the guessing for you. If you later go into thousands of memorized elements, your "gut" will fail you at some point. After all, it is not easy to guess which of your 100,000 items is closest to being forgotten

Jason Roos: When I need to memorize a bunch information, I make flashcards: 

1. I write a question on one side and an answer on the other
2. I gather all the cards up, and go through them one at a time
3. Those cards I get wrong, I set aside in a "don't know yet" pile. Those I get right, I set aside in a "know it" pile
4. After I've passed through the stack once, I pick up the "don't know yet" pile and repeat this sorting process until they've all been memorized

My gut is usually a good indicator of when I need to go through them again. If I feel confident, I know I'm ready to take the test. Intervals are not that accurately determinable, and 4 days for the first one, in my experience, is waaaay too long [in SuperMemo, the first interval will depend on the user and the learning material]. I need to pass through them every 30 minutes to an hour for at least a day, before they're reasonably secure in my head. Of course, it all depends on the type of material and how many days I slept in class. 
This method [SuperMemo] is hardly unique-- that's how many people study. And the effect is identical to your unnecessarily complex and rather tedious, I think, worksheets and software. It's surprising to me there seems to be so much scientific study behind it. I find it fairly simple and obvious

Internet addiction falls out of this site's focus
(Greg, Saturday, July 21, 2001 8:17 AM)
Question:
I am looking for professional information about IAD. Can you help?
Answer:
IAD falls out of this site's focus. We have found for you a couple of links with some interesting excerpts though:

• http://www.concentric.net/~Astorm/iad.html - Internet Addiction Disorder is the term first proposed by Dr. Ivan Goldberg for pathological, compulsive Internet usage. The criteria for this disorder are based on similar criteria for substance abuse disorders found in the DSM-IV. It is ironic that Dr. Goldberg was not serious about proposing this as an official diagnostic category, yet this term became used extensively. Dr. Goldberg recently revised his suggestion to change the term for this condition to Pathological Computer Use, and changed several of the criteria
• http://psychcentral.com/netaddiction/ - Do some people have problems with spending too much time online? Sure they do. Some people also spend too much time reading, watching television, and working, and ignore family, friendships, and social activities. But do we have TV addiction disorder, book addiction, and work addiction being suggested as legitimate mental disorders in the same category as schizophrenia and depression? I think not. It's the tendency of some mental health professionals and researchers to want to label everything they see as potentially harmful with a new diagnostic category. Unfortunately, this causes more harm than it helps people [...] 
  What some very, very few people who spend time online without any other problems present may suffer from is compulsive over-use. But compulsive behaviors are already covered by existing diagnostic categories and treatment would be similar. It's not the technology (whether it be the Internet, a book, the telephone, or the television) which is important or addicting -- it's the behavior. And behaviors are easily treatable by traditional cognitive-behavior techniques in psychotherapy
• http://www.victoriapoint.com/internetaddiction/articles.htm - Internet addiction articles

(Dawid Calinski, Poland, Apr 6, 2001)
Question:
Why does this site not mention learning in the relaxed state? What is your opinion about alpha waves in learning? Do you recommend products like BrainWave Generator, Hemi-Sync, Holosync or Polish Sita biofeedback?
Answer:
We do realize that the proper cognitive environment is paramount for learning. However, for clarity we use the term concentration instead of an all-inclusive relaxation. It is highly recommended that you maximize your concentration by taking into account the following factors:

• being cut off from all sources of interference in learning (telephone, e-mail, conversation, radio and even your favorite music)
• finding the optimum circadian timing for learning (e.g. early in the morning in free running sleep cycle, late in the evening in DSPS individuals who cannot afford free running sleep, etc.)
• all aspects of mental and cognitive health (e.g. stress avoidance, substance abuse, etc.)

The concept of relaxation is often associated with alpha wave learning which has attracted lots of companies that are more interested in their bottom line than their customers actual success in learning. EEG measurements can be used to generally conclude on the current state of the brain in the same way as you could detect bustling activity in a major city by scanning the surrounding electromagnetic field. The usefulness of alpha wave scanning in learning can be compared to the usefulness of electromagnetic field scanning for social life of a city. You need to focus on the causes rather than on symptoms. Alpha waves appear primarily in the absence of visual processing and other intense mental processes. This is why they cannot dogmatically be considered as a desired learning state. After all, the drowsy alpha state that precedes falling asleep is exactly the worst moment for learning during your day.

In evaluating the "relaxation products" you need to differentiate between the relaxation effect and the actual learning effect. The number of companies producing false claims in this field is astounding. It is very easy to fall for a simple solution to a learning problem (e.g. get 10Hz binaural beat difference and your learning problem will go away for life, and perhaps your sex drive will improve at the same time, you will sleep better and you will look younger). The easy learning solution explains why false claims related to "learning in relaxation" are so hard to extinguish.

At the same time, if you need to cope with stress or insomnia, many products in the field may have a legitimate application. Customers of the Polish Sita system jokingly claim that the company would do better if they marketed their product as a napping system. A worthy application on its own. If you know of relaxation products with legitimate claims and proven results, please let us know. We will gladly write about the subject or provide links from this website

Question:
(1) I want to spend my money on the MegaMemory program delivered on cassette tapes. How would you convince me, that I should rather spend money on buying SuperMemo (2) Is SuperMemo the same as SuperLearning developed by Dr Georgi Lozanov from Bulgaria? (3) Which techniques produce a greater increase in the speed of learning: SuperMemo or the mind maps proposed by Tony Buzan?
Answer:
The mnemonic techniques (Tony Buzan, MegaMemory, MindMan, etc.), Suggestopedia (Dr Lozanov) and SuperMemo can all be considered complementary. All of them have to do with optimization:

• In Dr Lozanov's method the stress is put on optimizing the cognitive environment which produces the best effects in the learning process
• In mnemonic techniques, the representation of knowledge is optimized in order to produce the most durable memory engrams
• In SuperMemo, the optimization concerns the spacing of repetitions

To be a successful student, you have to (1) apply mnemonic techniques while (2) using spaced repetition in a (3) optimum cognitive environment. The important advantage of SuperMemo is that many capable students develop quite good tricks as far as mnemonic techniques are concerned. They can also reasonably master their own psychology and physiology to subject it to the learning effort. However, they have no way of optimizing the spacing of repetitions. Mostly due to the fact that the amount and complexity of computation needed to determine the intervals require the use of a computer and the technology proprietary to SuperMemo World. You should always try to extract the best of the teachings of Tony Buzan and others; however, if you are a capable student, you may start off from learning how to optimize the timing of repetitions. As for now, SuperMemo is the world's best tool developed to assist you in this task

Question:
What is your opinion about Suggestive-Accelerative Learning and Teaching (SALT)?
Answer:
The problem with SALT is that it seems difficult to reproduce good results in learning with the method. The flaw may not necessarily be the method itself but its replicable employment (example). Similarly, it can be shown that learning vocabulary with SuperMemo is relatively easy and can be reproduced by self-taught individuals in nearly all cases. However, more advanced techniques, such as incremental reading, require a great deal of expertise and may, in experimental classroom conditions, produce inconclusive results! SALT may be the most representative implementation of the teachings of Dr Georgi Lozanov who himself had to disavow association with a number of teaching schools that try to pull his name under their own umbrella with tags such as SuperLearning, alpha wave learning, NLP biofeedback, accelerative learning, hypnosis, etc. Quality evaluations are scarce and practical applications may not be straightforward

Question:
Do you recommend books by Tony Buzan?
Answer:
Yes. These books belong to the classics of memory improvement and mental training. They also are very motivational. If learning is important to you, reading at least one of Buzan's collection is a must

(Peter Cool, The Netherlands, Nov 6, 1998)
Question:
Last weekend I started to read and exercise Kevin Trudeau's book Mega Memory. What is your opinion about this?
Answer:
MegaMemory is a good system to exercise your mnemonic skills. It is simple, strongly motivational and shall be useful for most students who want to strengthen their ability to master hard-to-memorize material.
The course, however, carries a couple of popular memory myths. Needlessly Kevin Trudeau begins his program with the claim that memories do not get erased as a result of forgetting and are simply becoming inaccessible. This is not true. The example used in the program refers to our bicycle riding skills. It is noted that people retain biking skills for years without repetition. However, biking falls into the domain of procedural learning (including touch typing, playing instruments, sports, etc.) as opposed to declarative learning (e.g. math, vocabulary, learning faces, etc.). Every minute of biking is equivalent to multiple repetitions in declarative learning and retention and forgetting are governed by slightly different principles. Information theory can be used to quickly prove that the brain is not capable of retaining all information in stores in long-term storage. Hence the need for forgetting. 
Note also that FTC has filed a lawsuit against Kevin Trudeau as a result of his marketing overstatements (the lawsuit was settled). Having said that we still strongly recommend Mega Memory or other mnemonic systems as a system complementary to SuperMemo and based on tried ancient mnemonic techniques. As a bonus, if English is your second language, Mega Memory tapes can additionally serve as a course of colorful English (narrated by Trudeau himself). See also: Mega Memory at SuperMemopedia and MegaMemory controversy

Mega Memory controversy
(Tim Stinnett, Mar 19, 2005, 12:42:27)
Question:
I was reading your FAQ and came across a section regarding Kevin Trudeau and his Mega Memory system. In addition to the criticisms of Trudeau already mentioned, you may want to add that Mr. Trudeau's memory apparently is so bad that he cannot even remember our criminal statutes or agreements he made with the federal government. Kevin Trudeau is a two-time convicted felon who served federal time for credit card fraud. Trudeau also was convicted on state charges involving check fraud and impersonating a physician
Answer:
As we may not be able to provide a thorough review of all products and techniques on the market, you can use SuperMemopedia to initiate review articles and place your opinions there. For example, click the Edit tab on the Mega Memory article and expand it to your best knowledge: http://wiki.supermemo.org/index.php?title=Mega_Memory. As for Mega Memory, this is an indisputably entertaining course of ancient mnemonic techniques. Those who do not want to support shady characters standing behind individual products can always look for equivalent alternatives

(M.Z., Poland, Apr 15, 2001)
Question:
While I make my repetitions, I often have problems with focusing on questions. My brain simply wanders off to other subjects. Do you think this is normal?
Answer:
This is a clear indication that your material is either badly structured or poorly selected. Unfortunately, this situation affects quite a number of users. Repetitions affected by concentration problems are dramatically less efficient. A wild guess is that you might be losing 50-95% of your efficiency. If you formulate your material poorly, you may suffer from recall problems (answers are too complex) or comprehension problems (questions are too wordy). Repetitions immediately become less enjoyable or even painful. This will quickly trigger natural defense mechanism. Your brain will search for more productive mental effort such as pondering over the movie you had seen a day before. Poorly selected material will produce exactly the same result. Optimally, you should only store top-importance material in SuperMemo. This comes from the fact that usually you hardly have time to master top-importance items, let alone anything else. If your material does not meet this criterion, it will seem less relevant and simply boring. If you cram for uninteresting exams, the result will be the same. Poorly selected or structured material is the chief cause of showing little progress with SuperMemo. Problems with attention are a clear indication that you need to review your learning process carefully. Probably you will need to do lots of deleting and reformulating. 
In addition, be sure you get enough sleep, avoid stress (e.g. make repetitions before school or work), do not let anyone disrupt you, turn off the radio and TV, turn off your music (even those pieces you love will compete with your items for your brain power). Please read: SuperMemo Decalog, esp. the section entitled Concentration

The term "staggered learning" may sometimes be used to describe "spaced learning"
(SKlein, Holland, Tuesday, December 05, 2000 7:32 AM)
Question:
What is the difference between staggered learning and learning based on spaced repetition?
Answer:
The term "staggered learning" is not used often. It may refer to intermittent learning or learning based on repetition and review. It is used in reference to the curriculum rather than the method of learning. Probably, its association with spaced repetition comes from the fact that it was used in the context of the Leitner method which is a very old form of spaced repetition

Reading also involves active recall
(Tomasz P. Szynalski , Mon, May 14, 2001 16:39)
Question:
I think your website overestimates the importance of active recall, esp. in learning languages. If I read 20 books (purely passive review), my result will be far from zero. On the contrary, my English skills will shoot up
Answer:
Active recall is needed to guarantee the high retention as defined by the forgetting index (even 99%). Depending on volume, structure, delay, etc. passive review may leave as little as less than a percent of recall. However, reading books for the sake of learning English is not just passive review. Each time you encounter a problematic word, the need for comprehension will automatically trigger an active recognition test in which the stimulus is the word in question and the response is its semantic association. This is active recall

Short-term memory requires no spaced repetition
(Mark G. Patterson, USA, Wednesday, July 18, 2001 6:24 AM)
Question:
The encoding phase of SuperMemo could be dramatically improved by providing a micro-spacing algorithm that presented each new item for recall 3 to 4 times during a 30 minute interval in an expanding pattern. For example, 0, 5, 15, 30 minutes
Answer:
Spaced repetition is valid for long-term processes and its purpose is to minimize the number of presentations and maximize the memory effect by sufficient spacing. However, improved recall within the span of short-term memory can be accomplished only in cases where the initial encoding was incomplete or insufficient. In other words, an important assumption in SuperMemo is that the first exposure should be used to formulate a valid memory engram that will last until the first repetition. Ideally, even the concept of final drill is excessive and serves solely as an insurance against imperfect concentration on the memory task. Sufficiently encoded short-term memories will always be converted to long-term memories and will likely last a few days until the moment of the first repetition

The more time you give to SuperMemo, the closer it will approximate your memory needs
(Luis Gustavo Neves da Silva, Brazil, Thursday, January 04, 2001 4:29 PM)
Question:
If I memorize a collection of 200 items with SuperMemo and make regular repetitions, when will my measured forgetting index be closest to the requested forgetting index: after a day, after a week, after a month or after a year?
Answer:
In conditions of no outside interference, the more time you give to SuperMemo, the better it will approach the requested level of retention. However, if you encounter this knowledge in real life (i.e. outside SuperMemo), the result cannot be predicted. For example, interference early in the interval may have no effect, while interference later in the interval may increase retention in the repetition to come and reduce the retention in the repetition that will follow yet another interval. The outcome will depend on the timing relationship of interference and measurement

Keeping things in memory is important! Memorization allows of employing associational thinking
(T.P.S., Poland, Fri, May 18, 2001 17:05)
Question:
What's the difference between persons A and B: Person A can recall thousands of facts in 5 seconds from memory. Person B can look up those facts in 30 seconds from the net. Clearly, person B is more effective, because he/she hasn't invested 30 minutes every day in appending the facts and then repeating them with SuperMemo
Answer:
Person A can produce instant associations between all those thousands ideas. If the number is 10,000, he or she can produce 10,000 x (10,000-1) instant associations of which many may appear useful (depending on the actual content of memory) Person B can produce only as many associations as his short-term memory can hold while browsing the sources (say 50 x 49 in case he can keep 50 things at once in short-term memory)

Delayed repetitions in SuperMemo
(Malcolm Macgregor, Saturday, September 21, 2002 12:32 AM)
Question:
What causes delayed repetitions?
Answer:
Delayed repetitions are usually caused by a user's failure to go through the allocated portion of the learning material. In massive incremental reading, delayed repetitions may also come by design as a result of material overload. Delayed repetitions will always result in an increased measured forgetting index (more forgetting) but can, paradoxically, save student's time by increasing memory consolidation (the speed of learning might be highest for forgetting index around 20-30%). Using Postpone, the student can choose portions of material that will be protected from delay in massive incremental reading. This way, important material takes more time to learn but shows a better recall rate

Forgetting curve for ill-formulated items is flattened
(anonymous, Wednesday, July 25, 2001 2:54 PM)
Question:
I had a 5-months break in using SuperMemo. I resumed my repetitions and noticed that I still remembered many items. Initially, SuperMemo asked me to repeat difficult items (e.g. enumerations). To my surprise, I remembered many of these items. SuperMemo required a 15 days interval, while I made my repetitions after 150 days and still succeeded. I no longer believe in the optimality of the SuperMemo algorithm. Probably it is 10 times worse than optimal
Answer:
Your results are in full compliance with theoretical expectations. It is no surprise that SuperMemo initially tossed the most difficult items at you, and it is no surprise that you showed remarkable recall on these items. Those items clearly belong to those that have not been formulated in compliance with representation rules (e.g. enumerations are notoriously difficult). If you imagine memories as sets of apples (you can see an apple as a single synapse in the brain), good memories are like small collections of well-polished apples. Bad memories (e.g. enumerations, complex items, ambiguous items, etc.) are like large collections of apples of which few are spoilt. Naturally, spoilt apples rot fast and make recall difficult. After just 15 days, all spoilt apples might have been rotten. During the remaining 150 days, the remaining apples rot very slowly. Hence the typical departure of wrongly formulated items from the shape of the classical forgetting curve. For bad items, the curve is flattened (as an expected superposition of several Ebbinghausian curves). SuperMemo blindly obeys your recall criteria. If it takes 15 days to ensure 98% recall, SuperMemo will take no consideration of the fact that at 150 days you may still show 95% recall. This is why SuperMemo 2000 includes leech management. It makes it easy to identify bad items and use auto-postpone or auto-forget options. Auto-postpone will do exactly what you expect, i.e. delay bad items with little impact on overall retention. Auto-forget will help you rebuild memories from scratch. Occasionally, the newly established memory representation will click and your recall will improve. Naturally, the best method against bad items is the use of appropriate representation (see: 20 rules of formulating knowledge for learning). Interestingly, SuperMemo can never predict the moment of forgetting of a single item. Forgetting is a stochastic process and can only operate on averages. A frequently propagated fallacy about SuperMemo is that it predicts the exact moment of forgetting: this is not true, and this is not possible. What SuperMemo does is a search for intervals at which items of given difficulty are likely to show a given probability of forgetting (e.g. 5%). If you look for a numerical measure of the algorithm's inaccuracy, instead of comparing intervals you should rather compare retention levels as the retention is the optimization criterion here. Even for a pure negatively exponential forgetting curve, a 10-fold deviation in interval estimation will result in R₂=exp(10*ln(R₁)) difference in retention. This is equivalent to a drop from 98% to 81%. For a flattened forgetting curve typical of badly-formulated items, this drop may be as little as 98%->95%

Multitasking is not recommended in learning (#6918)
(dansujp, Sun, Sep 16, 2001 3:07 PM)
Question:
Here is another improvement for SuperMemo. When I reviewed the flashcards, I would lay them out on a large table so that I could see 30 at a time, and would pick up the cards for which I knew the answer. Sometimes the answer takes a few seconds to surface. In the mean time I can be looking at other cards and thinking about them in a multitasking fashion. In SuperMemo there is only one question at a time, so it is frustrating to sit there and wait and not have anything else to do until the answer appears
Answer:
Research shows that multitasking considerably reduces cognitive powers. Optimally you should be able to focus on a single recall at a time. In addition, recall should, ideally, be instantaneous. Long and frustrating retrieval times would typically indicate ill-formulated items of high complexity. Your solution might increase the fun of learning for overly complex material, but if you apply the minimum information principle along with other pivotal rules of knowledge representation, multitasking would reduce your processing speed . In the past, we have added a number of options to SuperMemo by sheer user pressure; however, it can be demonstrated that in many cases this have actually done harm to user learning process. We consequently remove options that are frequently misused (e.g. Batch Repetitions, Background Repetitions, some rescheduling tools, and more)

Music and incremental reading
(Mohammed Asad Khan, Pakistan, Thursday, May 02, 2002 1:01 AM)
Question:
Can I read articles in SuperMemo with the help of my favorite music?
Answer:
Optimally, you should have your favorite music turned off when learning. However much it invigorates your brain, it will ALWAYS decrease your focus and take away some mental processing power. Invariably, background music reduces the efficiency of working with SuperMemo. If your learning is boring, you must diagnose the reasons. Most often, user knowledge is not properly formulated for active recall. Incremental reading may require a few months of practice to develop good learning habits. You cannot resolve the "boredom" of learning with background entertainment. Learning must be entertaining on its own!

Memorizing collections such as 20x20 Multiplication Table increases mnemonic computational skills
(Mark, Sun, Jul 29, 2001 2:48)
Question:
Once a user memorizes 20x20 Multiplication Table, will he or she be able to count properly without a calculator or pencil and paper?
Answer:
Yes. It is hardly possible to memorize 20x20 multiplication table without doing some simple calculations in memory. Cramming the results is neither recommended nor is it easy. The calculations made at recall stage actually enhance one's ability to run computations in memory, and decrease the need for a calculator!

Trust SuperMemo to save time
(Mike C, Thursday, September 20, 2001 2:46 AM)
Question:
I have a problem with Mercy. On 9/10 I answered an item, which was then scheduled again on 9/13. Then on 9/17 I ran Mercy. That item ended up getting re-scheduled to 9/19, today. What I'm seeing is that SuperMemo has assigned it an interval of 9 days rather than 3 days. The problem is that if I answer this item Good or Bright it is going to get scheduled out to something like 13 or 15 days, when it really should be only 4 or 5 days
Answer:
Once you get a good grade after a longer interval, SuperMemo will naturally use longer intervals as it will upgrade your recall chances. Your anxiety is understandable. However, by shortening intervals you would actually increase time needed for learning. What is worse, artificial shortening of intervals increases the chances of forgetting due to spacing effect

Memorizing instances of abstract cases is not a waste of time
(SuperMemo R&D, Wed, Aug 01, 2001 21:47)
Question:
In SuperMemo you propose to introduce several examples of the same rule. For example, 13*10=130, 24*10=240 and 69*10=690. One could get dozens of different possible appearances of one principle. Does this make sense?
Answer:
Yes. This is instance training. Problems you solve are instances of a certain abstraction. A single rule-based item requires a very smart mind to produce a strongly applicable abstraction. Several instance items help you make use of the natural properties of neural networks to enforce the abstraction. In many cases, you will achieve better results by memorizing a rule and several instances of its application than by just the rule alone. In SuperMemo, the cost of such a redundancy is negligible. Remember that in SuperMemo you spend most of your time on repetitions of difficult material. Redundancy improves retention by optimizing representation. Paradoxically, by adding redundant instance items, you can often reduce overall workload. And even if the workload were to increase, the applicability of thus-strengthen abstraction is a highly welcome side effect

Poor memory is usually a self-imposed limitation
(darran a., Australia, Mon, Aug 27, 2001 10:47 PM)
Question:
I was tested some years back for my memory, I always had problems learning at school, they told me I had a genetic short term memory loss, possibly inherited from my father, my children show some of the same signs that I have
Answer:
Please consult another specialist! Genetic factors affecting short-term memory are quite unlikely. In addition, it is the long-term memory that makes you succeed in life, while short-term memory can be honed easily with mnemonic training. Hopefully, SuperMemo should help you figure out that your abilities are not much different from others, and that your future rests in your hands (and your brain). Dozens of people claim they have poor memory only to find out, in measurement, that they do not differ much from others (except perhaps for some trainable mnemonic skills). Among those above forty, the claims of poor memory are epidemic

Vacation may feel like "improving memory"
(p.b., Thu, Apr 11, 2002 18:02)
Question:
When I came back from vacation, where I did not do my daily SuperMemo, some 1,500 items awaited me. I found out with surprise that I recall the items better after this 10-day break then on usual days with daily repetitions. Maybe my mind had so good rest that it worked noticeably better?
Answer:
If the vacation took away some stressload or gave you a chance to catch up with sleep, your fresher mind might partly explain a higher recall rate. However, you should also be aware of the placebo effect enhanced by the surprise that you remember so much. If your forgetting is usually 10%, you might have expected 30% after the vacation (as most people do expect). When you had noticed or sensed it is 12% (the more likely value), you could have felt as if it was 8%. It would "feel" as if your scores improved even though they were worse in proportion to the length of the delay

There is no remedy to interference
(Justin, Wed, Nov 07, 2001 23:58)
Question:
What should I do when I get two successive elements that are identical but flipped (i.e. the question goes in the place of the answer)? The first card obviously "refreshes" my memory -- so the "testing" of the second item is inaccurate. I usually just click Fail ('D'), which I is bad for the learning process
Answer:
Your only remedy is introspection and an honest attempt to estimate how you would have scored had the refreshing item not been presented. Otherwise, scoring Bad or Fail should not do much damage to the learning process. In the long run (i.e. when intervals increase) and with a high volume of the learning material, this is usually not a problem to worry about. Successive occurrence of similar items is rare in such circumstances

Spacing effect results from reduced potential for increasing synaptic strength
(Mark G. Patterson, Tuesday, September 25, 2001 3:25 AM)
Question:
Why is the term Spacing Effect used with negative connotations at supermemo.com? Spacing Effect refers to the beneficial effects of spaced repetition (which I prefer to call spaced recall since active recall, not mere repetition or review, is key)
Answer:
Forgetting and the spacing effect are beneficial from the evolutionary point of view as these both evolved to prevent memory overload. However, in the context of learning, both phenomena need to be struggled against by the student. Spacing effect may be interpreted as "shorter intervals - harder learning" or as "longer intervals - easier learning". In other words this might be a glass half-empty case. However, once we understand the molecular origins of the spacing effect, we quickly come to see it as a mechanism directed against remembering. In the same way, once we try to fill a glass with water, we will call it half-full in the middle of the way. Spaced repetition is effective exactly because it goes around the spacing effect, i.e. around the reduced ability to reinforce memories at high levels of retrievability

It is possible to roughly estimate the amount of time needed for learning a portion of material
(Patrik Nilsson, Tuesday, December 18, 2001 11:53 AM)
Question:
Can Tools : Statistics : Simulation help me figure out the date when it is expected that I manage my learning material?
Answer:
Once you introduce an item into the learning process and execute all outstanding repetitions, it is SuperMemo's responsibility to ensure the desired level of retention. For that reason, you can assume that you "managed" your material as soon as it has been introduced into the learning process. Consequently, you do not need to run Simulation. If you want to memorize 1000 items and you decide to introduce 10 items per day into the learning process, you will "manage" the material in 1000/10=100 days. Now you can use Simulation to try to estimate how much work this will require. A rule of thumb is that you need 10x more effort for repetitions than for learning new material. This could indicate that if you memorize 10 items per day, you may expect 100 repetitions per day (at least in the initial period). This number may vary greatly depending on the difficulty of the material and your learning skills and techniques. Use Simulation to get a better estimate. With rescheduling tools (e.g. Postpone), you can also reduce the daily load of repetitions; however, you will then suffer some loss in retention. Another rule of thumb is that to increase your forgetting index from 10% to 20% you would need to either (1) massively overload the learning process (e.g. by increasing the inflow of material 10-fold), or (2) dramatically cut down on the learning effort (e.g. by 90%). For more see: Theoretical aspects of SuperMemo

Use Simulation to estimate workload
(Piotr Wasik, Poland, Tue, Apr 24, 2001 14:26)
Question:
I would like to know how to estimate my workload on a large collection if I commit 40 items per day and keep the forgetting index at the default ten percent
Answer:
If you use Tools : Statistics : Simulation and set: (1) the forgetting index to 10%, and (2) daily repetitions to 230 items, you will get 40 new items memorized per day. In other words, your workload might roughly be 230 items/day (this will vary greatly depending on the quality of your learning material)

Tony Buzan and SuperMemo
(JON DOWAT, Tuesday, February 12, 2002 5:10 AM)
Question:
Is SuperMemo based on the memory research by Tony Buzan?
Answer:
Not directly. However, both SuperMemo World and Tony Buzan try to produce a synthesis of what is know about efficient learning. Those philosophies are largely identical. Our advice related to mnemonic techniques, although not part of SuperMemo itself, is largely based on Buzan thinking. Similarly, Buzan is a proponent of repetition spacing. His proposed increased interval scheme is slightly different from what comes out from computations made by SuperMemo, but is equally valid in practical, non-computer, applications. Tony Buzan has accomplished a great deal promoting "learning to learn" attitudes worldwide. His work fertilized the ground for seeding SuperMemo

Flatter forgetting curve does not increase optimum interval
(Tomasz P. Szynalski, Saturday, August 04, 2001 5:53 AM)
Question:
If the forgetting curve is flatter for difficult items, I will remember them for a longer time, right? Does that suggest that ill-formulated items are remembered better?
Answer:
No. Flattened forgetting curve will increase retention measurements in intervals that are a multiple of the optimum interval as compared with the typical negatively exponential curve for well-structured material. However, the optimum intervals for ill-formulated items will expectedly be shorter as can be observed on the first interval graph in Tools : Statistics : Analysis : Graphs : First Interval. The smoothness of this graph depends on the number of repetitions recorded. In the picture below, over 90,000 repetitions have been recorded

I don't buy memory overload hypothesis in Alzheimer's
(Mike, Tue, May 28, 2002 5:01)
Question:
I'm sure the basic premise of the "memory overload hypothesis" is flawed. The effect of SuperMemo is really no different, at the basic biochemical level, than any other repetitive learning activity (although certainly more efficient). If I dial my mother's phone number 100 times over the next few years, does that also contribute to Alzheimer's?
Answer:
It is important to differentiate between recalling/reusing old memories, and forming new memories. When you redial the same phone number, you are not likely to form new long-term memories. Nor does the overall storage change when you make repetitions of outstanding items in SuperMemo. However, the power of SuperMemo is in that the efficient rehearsal of the old material provides more time for learning new material. Consequently, you will be forming far more new memories than an average non-SuperMemo student. This would be exactly what Robin P. Clarke worries about: too much new stuff in your head. However, the evidence leaves little room for truly harmful overload (e.g. as in cramming in stressful conditions). If the hypothesis was right for the subset of cases violating the principles of mental hygiene, well-employed SuperMemo would not classify

First meaningful split into difficulty categories occurs at first repetition (#9873)
(Aaron Koller, USA Educational, Thu, Jun 13, 2002 5:25)
Question:
Ten days ago I had a collection with about 200 items in it. I reset the collection and learned all 200 items that day. Starting the next day, I added about 20-25 more items each day. My problem is: SuperMemo is scheduling the next repetition for the newly added items up to 5 weeks in the future, seemingly without regard what score I give it. It seems I will certainly forget an item I didn't know today if I won't seen it again until next month
Answer:
It takes time for SuperMemo to be highly accurate with ensuring the requested retention of knowledge. Your poor grades next month will help it improve its performance. The first interval of all new items is computed with the same forgetting curve. This means that both difficult and easy items will be scheduled at the same time. The first grade given after this uniform interval is the first tool SuperMemo uses to estimate item difficulty. It cannot use grades provided while memorizing because these can pertain to completely unknown material as well as to material that has just been introduced manually. If you scored excellent on those first 200 items, all following items will be first scheduled at a much longer interval (i.e. the optimum interval for new items whose difficulty is not known). In simple terms, SuperMemo has no way of knowing that you have already worked with the first 200 items and your grades are exceedingly good. Nor can it know that the follow-up items are far more difficult. The only hint of irregularity will come with grades received in repetitions. For that reason you will need to wait as long as the first interval (up to 20 days) and you will need to process comparably many difficult items (i.e. around 200) to proportionally shorten the first interval. The average first interval may reach 20 days, but rarely, due to interval dispersion you might see items scheduled in over four weeks (i.e. 20 days plus the dispersion interval which follows a normal distribution). 

You have two choices: 

1. wait until SuperMemo discovers the fact that your first 200 items were unusually easy 
2. use File : Tools : Reset parameters : Optimization matrices to begin building your memory model anew 

A good practice is to keep all your knowledge in one collection to avoid similar deviant behavior. All forms of intermittent learning (e.g. relearning the material, breaks in learning, etc.) make it difficult for SuperMemo to build a good memory model

The Silva method does not seem to be based on solid science (#9892)
(Staszek, Poland, Jun 14, 2002)
Question:
Do you recommend the Silva method?
Answer:
Although there have been many people genuinely happy with the Silva method, we do not believe this method has a solid scientific basis. As a result, we have no reasons to recommend it. Please consult other sources too. See also: Silva Method (Skeptic's Dictionary)

Limited Postpone will not damage your learning process (#219)
(Mariusz, Jun 17, 2002)
Question:
How much does my retention drop when I use Postpone?
Answer:
For an ideally exponential forgetting curve we can show that:

R_d=e^{(ln(1-FI/100)*dp)}

where:

• R_d - retention after the delay caused by Postpone
• FI - forgetting index (in percent)
• d - delay factor in Postpone (i.e. the number by which the length of the interval is multiplied)
• p - the number of postpones (d^p is here the cumulative postpone factor)

The table below shows that even a large number of postpones is insignificant as long as the delay factor d is low (you can choose this number in the postpone dialog box). However, the default delay factor of 1.1 will increase the forgetting index from 10% to 20% if postpone is executed successfully seven times in succession.

Table: Increase in the measured forgetting index as a result of using Postpone among items with the requested forgetting index equal to 10%. Grey column headers: delay factor. Yellow row headers: number of postpones. Table body: measured forgetting index. Blue area: measured forgetting index above 20%

It is harder to learn foreign languages after forty (#5828)
(Pawel W., Poland, Aug 07, 2001)
Question:
I have been learning English for several decades, but I still speak poorly. My IQ is well above average, I am not lazy, and otherwise I have a fluent command of the language. I learned Esperanto in a few weeks and speak good German. But speaking English is always a problem. Any suggestions?
Answer:
Over the years, you have certainly acquired phonetic, lexical and mnemonic representation patterns that deprive you of rudimentary building blocks that enable fast learning of languages other than your native one! If you play with the Polish word "start" in your memory, you use a very scanty synaptic representation that makes processing fast and retention easy. If you want to use the word "start" in English, suddenly you are faced with a burden of connotations that make learning quite frustrating. The mere pronunciation pattern may require weeks of effort devoted to a single vowel. You need specialized circuitry to process this single vowel, extract it in the flow of speech, pronounce it in different contexts, skip it when possible, and emphasize when necessary. Your language toolkit has already been molded to fit your native language. It is not true that you learn slower than young kids. Your main obstacle is to unlearn hundreds of neural dogmas about the language. Then you need to develop anew specialized circuits for processing building blocks of speech. The shortest path to resolving this problem is to find people to who you will be able to speak English and use the language as often as possible. Fill up the gaps in knowledge with SuperMemo. Each time you pause on a word or phrase while its Polish equivalent is ready to serve in your memory, store the appropriate association in SuperMemo (e.g. Polish word vs. English word, and later, English word definition vs. English word). Only with months of intense training will you be able to overcome mental obstacles that also grow in your mind with each frustrating year of limited progress. All in all, it may appear easier to develop a fluent command of spoken English that to learn to decode various dialects of English from all corners of the world. Again untold hours of training are needed to achieve proficiency. You may greatly simplify your task if you definitely decide not to struggle to get rid of your Polish accent. International communication needs to strive to never discriminate between individuals on the basis of their accent

SAFMEDS skills are useful in incremental reading
(TKMan, May 25, 2003)
Question:
I read about a special kind of flashcard training called SAFMEDS. Do you recommend it?
Answer:
Yes. SAFMEDS can shortly be characterized as the art of cloze deletion formulation combined with precision teaching. What you learn from SAFMEDS will directly translate onto a subset of skills employed in incremental reading. Note, however, that SuperMemo does not employ nor universally recommend fluency drills typical of precision teaching. 

The art of SAFMEDS emphasizes the core principles of efficient learning (and SuperMemo): active recall and minimum information. It also formulates the rules of cloze deletion formulation (here: SAFMEDS card construction criteria): uniform blanks, blanks at the end of the sentence, minimum wording, multiple cards for multiple keywords, etc.

Advanced repetitions and the spacing effect
(Malcolm Macgregor, Saturday, September 21, 2002 12:32 AM)
Question:
Could you explain how repetitions advanced in time relate to the spacing effect?
Answer:
Before an important exam, the student may decide to review a portion of material even though individual items may be scheduled for repetition months or years into the future. The spacing effect prevents memory consolidation when inter-repetition intervals are far shorter than the chosen optimum. For that reason, formulas used in earlier versions of SuperMemo cannot be used to compute a new interval after the forced premature repetition. Instead, a heuristic formula is used to shorten the interval accordingly. For example, if the optimum interval was 1000 days and the next optimum interval was to be, say, 1300 days, SuperMemo will use the interval range from 1000 days to 1300 days for premature repetitions. If the repetition takes place 10 days after the last review (instead of 1000 days), it will have nearly no effect on memory consolidation and SuperMemo will choose 1000 (or 1001) as the next interval. However, if the repetition takes place on 900th day, SuperMemo will assume it is nearly as effective as the optimally scheduled repetition and schedule the next repetition in, say, 1297 days. The formula for "interval attenuation" is not based on hard science but is good enough for practical applications where advanced review is an exception rather than a norm

Automaticity does not correlate with the probability of forgetting
(Terje A. Tonsberg , Tuesday, July 08, 2003 8:51 PM)
Question:
How highly correlated is low latency in answering a question (high automaticity) to the probability of forgetting?
Answer:
There is no correlation between automaticity and the probability of forgetting in the period that follows the measurement. In the terminology of the two variables of long-term memory, automaticity is correlated with retrievability, while probability of forgetting in a given period (assuming the same known retrievability) is correlated with memory stability (also confusingly called memory strength). In simple terms, if you remember something very well, you do not know how fast you are likely to forget it. It depends on the history of previous exposure. For example, in SuperMemo, the automaticity of recall is similar after the fifth and after the tenth repetition. However, memories built in ten repetitions are likely to last far longer. Perhaps even a lifetime. Mathematically speaking, retrievability R(t) corresponds with the probability of retrieval of a memory trace at the time t. Probability of forgetting in the time d will then be R(t)-R(t+d). However, R is the function of memory stability S: R=e^(-t/S). Hence we have the probability of forgetting as P(t,d)=e^(-t/S)-e^(-(t+d)/S). Predictably, the stronger the stability, the less forgetting you will see. The starting point retrievability is not included in the equation, because it is the steepness of the forgetting curve, not the starting point, that determines the speed of forgetting. 

It is worth noting, that with biased statistical sampling, it might be possible to erroneously prove the false hypothesis of the negative correlation between automaticity and probability of forgetting. This comes from the fact that very low retrievability will always produce very low probability of forgetting nearly independent of memory stability (at the bottom of the forgetting curve). No wonder then, that in "traditional learning" (i.e. not based on spaced repetition), where both retention and stability are much lower, it is easy to falsely assume that if you know something well, you will remember it far longer than if you show recall problems

SuperMemo should not be viewed as a cramming tool
(Gundam Fool, Monday, February 18, 2002 1:00 AM)
Question:
What about applicability? For example, I memorize a math formula with SuperMemo, should I also add an item that makes me use this math formula so I also remember how to apply this math formula to a problem? Or is the associative thinking part separate from SuperMemo and I should only memorize facts and formulas?
Answer:
You can use SuperMemo to boost creative thinking as well. The optimum approach to formulas will depend on your particular needs. Simple formulas may be self-containing and applicable in many contexts without additional clues. The connection between others and relevant models may be less clear. Then, depending on your needs and the priority of the formula, you can add examples, anecdotes, loose associations, mutated formulas, formula derivation, instances to solve, etc. If you do not have much experience with SuperMemo, start with raw formulas and see how they work in practice. If a formula becomes "dry" and unassociative, you can support it with additional material. You can, for example, think over the formula and its known association and describe it in prose in your own words. Then you can dismantle that prose in incremental reading and gradually build a better understanding of the formula's applicability. Using prose and incremental reading will be equivalent to perpetuating your today's understanding of the formula and, as a bonus, deepening associations with individual components of the model

We believe SuperMemo is a must for anyone with serious plans to enter science
(Garry Gross, Saturday, August 25, 2001 12:24 AM)
Question:
I am presently studying to be a behaviorist. I am working from text books that I find difficult. Please let me know how SuperMemo would be useful in this adventure. How do I get the material from the text into the program?
Answer:
This article is probably the best summary of the role SuperMemo could play in your work: Devouring knowledge.  Please pay a special attention to the part devoted to incremental reading. We believe that incremental reading is a must for anyone with serious plans of working in science. The most painful limitation in your context is that incremental reading requires your texts to be available in electronic form (e.g. if you rely on paper books, you would need an OCR scanner or you would need to type in the most essential study points into the computer)

Minimum information principle v.s. the length of "20 rules" article
(NF Lynch (Isr), Israel, Wednesday, January 15, 2003 9:29 AM)
Question:
Your list of The 20 rules of formulating knowledge in learning flies in the face of your own learning principles. The list is too long and without any hierarchical basis or mnemonic hooks
Answer:
The minimum information principle refers only to active knowledge. Passive knowledge can be processed incrementally. In incremental reading, there is no upper limit on the length of texts that can be processed efficiently. Once the individual rules listed in the article are memorized using, for example, cloze deletions, they need to meticulously adhere to the minimum information principle. In other words, articles you read can be outrageously long. It is the answers to questions you want to remember that must be short

Spaced Application & Semantic Networks (#3831)
(Mark G. P., Thu, Jun 21, 2001 6:24)
Question:
I read a question in Medical Biology: 
Q: mem: What is the impact of blocking phospholipase A2 on inducing LTP? 
A: Suppression 
Uhhhhhhhh …… but if I don't have a clue what phospholipase A2 is then this item becomes meaningless. Sure, if I pound away at recalling fuzzy, shallow memories of meaningless items, eventually I may encounter the information I need and the lights will come on, but is this the most efficient way to learn?
Answer:
Rule #1 in selecting and formulating your learning materials is: Do not learn what you do not understand! (see: 20 rules...).
The correct action upon encountering such an item is one of the following: 

1. for low-priority material, Forget the item and place it at the selected location of the pending queue (Ctrl+R) 
2. for more important material, postpone the item until the time you believe you are likely to understand it (Ctrl+J)
3. for vital material, review your collection for the "missing link" (Search and Review) or import new articles discussing the subject 

Ideally, you should create your collections on your own; however, ready-made material may also be useful if it belongs to a well-defined and well-targeted subset, or if it is used as a complementary inspiration rather than a supplement for wider study. Medical Biology is sorted by difficulty but it is unlikely to be fully understood even by students of medicine. For that reason, complementary research and incremental reading will always make a vital addition to studying this material

Why is SuperMemo slow to show its strength?
(Nathan Crow, WedJun18,2003 4:14 pm)
Question:
Why do you say one cannot see any difference between SuperMemo and other flashcard systems until a week has passed? Odd, if true.
Answer:

SuperMemo uses spaced repetition. Inter-repetition intervals increase gradually in the learning process. The more you grow your intervals, the less time you spend on repetitions, and the more time you have to enjoy stable knowledge.

If you compare SuperMemo with reading a book, you will see little difference in retention in the first week (first intervals in SuperMemo are usually shorter than a week). If you compare results after a month, an average book reader will have already forgotten a large part of the learned material, while the user of SuperMemo will stabilize around the programmed level of retention.

The more time passes, the greater the difference between traditional learning and SuperMemo.

If you compare SuperMemo with other methods approximating spaced repetition (e.g. priority system, Leitner system, etc.), it may take even longer to demonstrate the difference in retention.

The statement "give it a week before you give up" is to alert a new user to the fact that return on investment in the first week is little. There is a point in time (say several days) before which using SuperMemo may take more time than learning in a traditional way.

Considering the complexity of SuperMemo, difficulty in efficiently formulating knowledge, and the skills needed to master techniques such as "incremental reading", it is important for new users to realize they will need lots of patience before collecting their first ripe fruits of wisdom

You can easily learn 10,000 items per year
(Robyn Harte-Bunting , Monday, October 06, 2003 4:39 PM)
Question:
In the website you state that it is difficult to maintain a schedule of more than 100 daily repetitions or 1 hour per day on SuperMemo for lengthy periods. Can you say more about this number?
Answer:
Those rather arbitrary numbers depend on many factors. Beginners should take far lesser loads. Advanced users may go well beyond that, esp. with incremental reading and related skills. Nothing will serve as a better guidance as your own experiments probing the difficulty of knowledge you plan to master, your skills in formulating knowledge and the degree to which your personality or the type of acquired knowledge will make the whole process enjoyable as opposed tiresome. Some anecdotal facts may help you in measuring your maximum load: 

• advanced users report that acquiring 10,000 new items per year seems rather effortless 
• some determined users are able to sustain 1000 repetitions per day for a week or so (that is a full-time job though)
• one user reported memorizing the whole Advanced English (40,000 items) in less than 6 months 
• very few users report reaching more than 400 repetitions per day for longer than a few months 
• incremental reading, where topics are mixed with items, is by far more enjoyable than pure repetitions, and can lead to far longer hours spent with SuperMemo 

As for incremental reading, advanced users report little or no fatigue even in 3-5 hour non-stop runs (assuming a fresh unstressed mind). This may partly come from the material variety (randomized presentation of topics has a "TV channel zapping" reward effect). Also, the passive nature of topic processing may contribute to resolving short-term memory overloads that quickly result in homeostatic fatigue in traditional SuperMemo. 

All in all, if you master all skills related to incremental reading and knowledge formulation, if you test your personal persistence and self-discipline, you may be able to commit yourself to 100 items per day plus 100-400 topics per day. However, as this may take 2-4 hours of learning, it is highly recommended you split those high loads into portions. If you give up on retention (say down to 85-90%), you can maximize the learning speed and reach 30,000-50,000 new elements per year. Of these, depending on the strategy, 30-60% will be items (still rather less than 15,000-20,000).

Remember, that you will need to use your best creative hours to sustain this process in the long run. Assuming you sleep in accordance with you natural circadian rhythm, those hours would be early in the morning (after breakfast) and perhaps in the evening peak (if you experience one). If you happen to learn at sub-optimum time (e.g. after work), you may find it hard to do a quarter of the suggested load

Learning to do calculations in memory
(Dragan Vidovic, Netherlands, Wednesday, March 10, 2004 9:25 AM)
Question:
I am trying to learn to calculate quickly in mind. I am a mathematician, and this is a hard problem form me, because I use a calculator since I was ten. The main problem with calculating in mind is memory
Answer:
You are right. The amazing feats of Rudiger Gamm are based on memory and the right techniques. You should begin with learning mnemonic techniques relevant to mathemetical calculations (e.g. peg system). Then you could try to learn a couple of rudimentary SuperMemo collections (e.g. Multiplication 20x20, Division 20:20, Division 1/20, etc.). While working with basic collections you will hone your own mnemonic techniques useful in basic calculations. Then you can gradually expand the difficulty of the material used in your practise. Ultimately, if you aim high, untold hours of practice are sine qua non of success (Gamm used to spend whole days practising).

Mega Memory and SuperMemo are complementary
(Dave 42914882, Wednesday, June 26, 2002 7:45 AM)
Question:
I bought a product called Mega Memory. How does it compare to your system?
Answer:
Mega Memory will enhance your mnemonic skills. SuperMemo will help you remember for ever. Mega Memory improves your short-term memory skills. SuperMemo builds long-term memory. If you use SuperMemo, you eliminate the problem of forgetting. If you combine it with Mega Memory, you will accelerate the speed of learning by being able to formulate your material in an easy-to-recall way. See also: Mega Memory at SuperMemopedia

See Skeptic's Dictionary for a skeptical analysis of NLP
(konrad, Jul 03, 2002)
Question:
What do you think of NLP?
Answer:
Skeptic's Dictionary provides a highly skeptical review of neurolinguistic programming

Axon software
(Nick Sadler, the Netherlands, Aug 05, 2002)
Question:
What do you think of Axon Idea Professor? Would you recommend it?
Answer:
We have not tried Axon. The software seems highly innovative. Some SuperMemo customers expressed positive opinions

There is a physical limitation on how much we can learn per day
(Robyn Harte-Bunting , Friday, February 20, 2004 5:15 PM)
Question:
Alan Baddeley's 1976 book "The Psychology of Memory" (Chapter 2 "Input Limitations") cited an experiment in which postmen were taught to type on a variety of schedules. The results strongly indicated that there is a definite limitation, probably physical concerning the consolidation of the memory trace, to how much can be learned in a day and that too much effort led to negative returns. Are you aware of any research quantifying this limitation, which is distinct from the more pragmatic SuperMemo limit on the amount of review necessary for too large an input. How many items, inputted for the first time, outstrips the brains capacity to consolidate them as memories?

The postmen experiment was described in "The Psychology of Memory" and again in his more recent "Your Memory, a User's Guide". Baddeley's experiment showed that of 4 groups of postmen who learned to type over 60 hours, the one hour a day group attained a far higher skill level than those who practised 4 hours per day, 2 hours per day in one session and those who did 2 one hour sessions. In fact, the data shows that the 4 hour group must have experienced negative returns at some point. He describes a
similar result in a wartime experiment in groups learning Morse code. This is odd, in that in "Genius Explained" by Rowe a
common finding in individuals of very high ability is that they have put in typically 10,000 practise hours before virtuoso performance is achieved. They do not work "little and often" as the experiments would suggest.

Baddeley hypothesizes a limit to the daily learning rate and suggests it is based on time need to physically consolidate memory traces. In practical terms, it is very important to be able to quantify this limit in order to have efficient learning and practise.

Answer:
There is indeed a limit on how much we can learn per day. However, with good strategy, there does not seem to be a limit beyond which we should stop learning.

First we need to draw a distinction between procedural learning and declarative learning. Procedural learning is used to acquiring a skill such as riding a bike or typing the keyboard. In procedural learning, we do not tell the brain exactly how it should perform. The brain provides "the answer" on its own by trial and error, while we only "approve or disapprove" of its performance. In declarative learning, as in memorizing a textbook, we tell the brain exactly what to learn, and expect it to encode information in memory. Procedural learning, by definition, is highly repetitive (you repeat the same moves again and again, only with a slightly improved precision). With declarative learning, we want to minimize the repetition. For those reasons we need to discuss the two types of learning separately.

Procedural learning

In procedural learning, as in the typing postmen experiment, the following factors may result in the need to stop the practise at some point:

• the law of the diminishing returns: after a longer practise, there is less and less improvement in unit time. This makes learning inefficient. It is far more practical to switch to another training procedure to capitalize on higher returns
• fatigue: procedural learning often involves a strain on the motor system (e.g. carpal tunnel syndrome may be a result of excessive use of the keyboard). This calls for strict limits on the amount of practise, esp. in novices
• degrading attention: if mental fatigue will result in loss to attention, the "command system" will not efficiently "supervise" the learning procedure. This may result in un-learning!

If you see virtuosos practicing all day long and getting excellent returns, it all comes from the mastery of the learning procedure itself. A top-class violinist will counter-act all factors that put the limit on the recommended amount of procedural learning. She will switch the routine to avoid diminishing returns. She will keep her entire upper limb motor system in excellent shape to effectively avoid overuse injury. Most of all, she will master the art of attention and capitalize on her passion for the violin to avoid the effects of un-learning. Consequently, there will always be a natural limit on her daily progress, but there may be no limit on the amount of training other than the need to take breaks (e.g. for lunch) and the need to sleep (to consolidate the results of learning). 

Declarative learning

As in procedural learning, there are factors that will limit the efficiency with the progress of learning on a given day:

• the law of diminishing returns: with spacing effect, repeated review of the same material quickly results in a complete absence of progress. Even worse: excessive review may prevent effective consolidation of long-term memories. If you get a new credit card and a new PIN code, you are likely to remember your PIN as long as you use it often. However, a short break in use may result in a sudden inability to retrieve the PIN code from memory. The memory lapse is far less likely if breaks in use increase gradually allowing of long-term consolidation that is not possible or difficult with frequent use of the memory in question.
• fatigue and degrading attention: the amount of new information we can acquire in a single day is huge. Scientists hypothesize that we are able to take in so much due to evolving a two-component memory system: short-term fast-coding sparse low-volume memory and long-term slow-coding dense high-volume memory. The two systems have evolved to resolve one of the greatest problems of memory: interference (i.e. confusing similar pieces of memory). The short-term system encodes memories fast but uses lots of space to avoid interference. The long-term system slowly encodes memories in the optimum way that minimizes interference. The practical effect of the two-system memory is that with passing hours, we are less and less effective in acquiring new information. We tend to confuse things and get irritable. Our defense is fatigue. Our solution is sleep. Sleep is a great memory optimizer!
• ill health effects of over-learning: it has been hypothesized that excessive learning may lead to ill effects on the memory system. See: Can too much learning cause Alzheimer's?

In declarative learning, unlike in procedural learning, we can accomplish maximum speed of learning if we minimize the review of the material with a view to a selected level of knowledge retention. For each selected retention level, there is an optimum review schedule that can easily be computed (as in SuperMemo). Maximum speed of learning is reached if we allow 20-25% of the material to be forgotten by the time of review. For higher retention levels, knowledge acquisition rate is slowed by the rapidly increasing frequency of review. For lower retention levels, knowledge acquisition is slowed by forgetting. In practise, for excellent long-term results we elect to remember anywhere between 80 to 98% of the learned material. For most important material, we choose higher retention at the cost of lower knowledge acquisition rate (i.e. learning speed).

The existence of the optimum schedule of review and the optimum knowledge representation makes it possible to determine the natural limit on the amount of information acquired in unit time over lifetime. This limit has been variously estimated in the range of millions of individual pieces of information (e.g. flashcards, questions&answers, items in SuperMemo, etc.).

As it was the case with procedural learning, a skilled student will also be able to spend long-hours on declarative learning without suffering negative effects. He will use spaced repetition to optimize the learning schedule and avoid spacing effect (SuperMemo). He will formulate knowledge for learning in the way that will minimize interference, minimize fatigue, and maximize consolidation (see: 20 rules of formulating knowledge). Finally, he will take the break from learning with increasing fatigue and never neglect sufficiently long and sound sleep that is the best warranty that the day-long learning is optimally consolidation for long-term objectives.

Conclusion: the key to overcoming the limits on the learning rate and the daily amount of learning is the learning skills. Those vital skills include: understanding optimum knowledge representation (how to formulate questions, what training procedure to choose, etc.), understanding optimum repetition spacing (when to make the review), understanding fatigue and sleep, passion (love of learning), overall fitness, time-management, stress-management, etc. All these skills are discussed in detail at supermemo.com

Herbert Simon guess on the expert memory power reflects his genius
(Dawid C. Poland, Aug 14, 2003)
Question:
Nobel Prize winner Herbert Simon claims that it takes 100,000 to 2 million "memory patterns" to make an expert. How does it square with your estimations based on SuperMemo?
Answer:
Simon's estimate is surprisingly accurate considering the fact that he did not use any mathematical formulas for estimating the forgetting rate. He started off with a very rough estimation of time needed to establish a single memory pattern and used his "10 years of hard work" prescription for an expert. However, the number 100,000 is probably closer to the real memory power of an expert. Anything beyond that will hit the wall of knowledge management that can only be overcome with tools like SuperMemo

Ages old techniques are still valid
(J.Tomlison, Mar 04, 2002)
Question:
Do you recommend techniques such as positive attitude, visualization, concentration, etc.
Answer:
Yes. Positive attitude works in all walks of life. Visualization makes things easier to remember. Concentration is vital for encoding memories (the sharper the laser light, the better the etch). Those things are all listed in SuperMemo Decalog

SuperMemo does not use microspacing of repetitions
(mgpatterson, Thursday, August 23, 2001 5:16 AM)
Question:
While I have complete confidence in SuperMemo scheduling algorithms, I needed to modify the operation of the final drill. From my research I've concluded that it is critical during initial encoding (when a student is first learning an item) that they are required to recall it at least 3 times during a 30-minute window--even though they may fully "know" the item each time. This repeated micro-spaced active recall (overlearning) leads to a neurochemical cascade that shifts the association into Intermediate-Term memory (lasting up to 3 days)
Answer:
Unfortunately, we cannot agree that microspacing is an effective way of using student's time. We are not aware of neurochemical variables needed to consolidate long-term memory other than those described in the SuperMemo model. In this light, final drill is only needed as a tool for coping with negligent/imperfect repetitions. Ideally, a single repetition and activation of short-term memory is all that is needed to begin the long-term consolidation phase. We are open to discussing your research in detail though

The effectiveness of passive review may be dismal
(Janusz Jezierski, Jul 18, 2002)
Question:
If active recall is so important, what is the purpose of topics in SuperMemo? How efficient would learning be if I never used items?
Answer:
The main purpose of topics is to collect learning material that will be processed to formulate questions and answers. With topics you do your reading. With items you do your learning. Learning based on topics would be dismal in quality. Experiments show that you may review a sentence passively 20 times, and after the interval of just forty days you may be unable to recall you have ever read or seen the sentence! The more material your process in learning, the more likely you are to see this scary weakness of human memory. The power of SuperMemo is in simplicity of questions, active recall of items, and reviewing the material regularly as demanded by SuperMemo

There is no harm in "memorizing" things you already know
(Comcast Mail , Saturday, December 20, 2003 7:11 AM)
Question:
How do I add to SuperMemo knowledge that I previously acquired (i.e., facts that I already know or that I only recently forgot but initially learned without the aid of SuperMemo)? I want to add this knowledge to avoid forgetting it again
Answer:
You can add this knowledge in the same way as facts that you do not know. There is little harm to the overall learning process as this material will quickly be classified as "easy". To save time on needless repetition, you could additionally set the first interval on individual items (or topics) to an appropriately longer value (Ctrl+J). For example, if you believe you are not likely to forget an item for 3 months, you could set the first interval to 99 days or so.

Repetition category is used to update optimization matrices
(Steven Trezise, USA, Apr 20, 1999)
Question:
In my collection, I have items for which I have done between 1 and 8 repetitions. However, when I look at the Cases matrix, there are no entries beyond repetition 3
Answer:
The algorithm used by SuperMemo updates all optimization matrices using repetition categories, not the actual repetition number (you can view the optimization matrices with Tools : Statistics : Analysis : Matrices). A repetition category is an expected number of repetitions needed to reach the currently used interval. Once the matrices change, the estimation of repetition category may change too. If, for example, you score well in repetitions and your intervals become longer, it will take fewer repetitions to get to a given interval. In such a case, you might be at 8-th repetition while your repetition category will be 3. All matrices such as OF matrix, RF matrix, etc. will be updated in the third row (not in the 8-th row)

First Grade vs. A-Factor graph data is kept as a collection of trailing averages
(WangDong, China, Dec 08, 2003)
Question:
You say that "At each repetition, the current element's old A-Factor estimation is removed from the G-AF graph and the new estimation is added". But I found a different result. I have used a collection which has only one item. After many repetitions, I saw the G-AF graph. I found many changes (not a single point change). Only one point in the G-AF graph should change, because there was only one item in the collection. I guess your algorithm is: "In the G-AF graph, for every A-Factor value(1.2-6.9), calculate the average first grade of the items which have this certain A-Factor. When the A-Factor of an item is changed, calculate the average first grade of the corresponding A-Factor again. Is it right?
Answer:
Your reasoning is absolutely correct! However, to minimize the size of data kept by the algorithm, SuperMemo does not use averages to compute the first grade for each A-Factor category. Instead, it uses trailing averages. This way, instead of storing a large sum and the number of cases recorded, SuperMemo stores a single short number expressing the average first grade. This approach saves space, but does not make it possible to correct averages once A-Factor changes. SuperMemo simply computes the new trailing average for the new A-Factor. This is why a single item can introduce a lot of noise in the graph. Please note that the weight for averaging is highest for Repetition=2 where A-Factor is the same as O-Factor. For that single repetition, you should see the greatest change in the graph

Putting things in the same place is a good idea
(mnemonique, Jul 07, 2002)
Question:
Some memory tip websites recommend that we always put things in the same place. This way we never forget where they are. I thought that we should do just the opposite. Should we not train our memory as opposed to making things easy?
Answer:
Life is a process of perpetual learning. If you put things always in the same place, you will economize more time for learning more useful things. You will never run out of the material for training your memory. It seems far more useful to memorize with SuperMemo the geography of South-East Asia than to spend time on a key hunt

Higher grades can produce shorter intervals
(Mohamad Syafri, Aug 05, 2004, 16:36:09)
Question:
I think that lower grades, e.g. Pass (3), should produce shorter intervals in comparison to higher grades, e.g. Bright (5). It is not always so in the SuperMemo method. Why can I not see the correlation between intervals and the grades given in learning?
Answer:
This is not an error in the algorithm. In SuperMemo, lower grades may produce longer intervals because of a number of reasons:

1. Random dispersion: All intervals are always slightly dispersed around the optimum value. This results in more accurate plotting of the forgetting curves. In addition, interval dispersion prevents large variations in the number of repetitions executed on a single day. If you cancel the grade a few times, you will see that at each try, SuperMemo will provide a slightly different interval. Those intervals are normally distributed around the optimum. This means that most of the times, the deviation is little, but occasionally SuperMemo will schedule the element at an interval that is quite different from the optimum interval. Even if all the remaining reasons listed below do not apply, it may happen that lower grade will result in a longer interval by mere chance (esp. for lower forgetting index values that may approach bordering conditions on interval change) 
2. Incomplete information: Early in the learning process, SuperMemo is gradually modifying the function of optimum intervals. The speed at which the change occurs, depends on the number of repetitions falling into a given category. By definition of SuperMemo, good grades are prevalent and optimization for the corresponding A-Factors proceeds faster. It may happen that for a few weeks, for a range of A-Factors, lower grades will produce longer interval
3. Spacing effect: Grade Pass (3) may result in the enhancement of the so-called spacing effect, which may be less visible for Bright (5). The spacing effect says that longer intervals, and consequently greater recall efforts, produce more stable memory engrams. SuperMemo does not arbitrarily set the function of optimal intervals. It computes intervals which are most likely to result in the requested forgetting index
4. First grade: At memorizing pending items, SuperMemo ignores grades as it has no way of knowing how a given items found its way into the collection. For example, a good grade might result from the fact that the item has just been introduced to the collection

Your impression of no correlation between grades and intervals is quite common among those who begin their work with SuperMemo. If you are not sure if the reasons listed above are legitimate, you can monitor your retention with Tools : Statistics : Analysis : Use : FI. This way you can be sure that SuperMemo will keep its promise of reaching your desired knowledge retention (assuming appropriate formulation of the learning material)

SuperMemo discourages mindless memorization
(Stephen R. Diamond, Jul 21, 2004, 17:55:23)
Question:
Does SuperMemo encourage excessive reliance on memory, on using memory where reasoning would be more productive? Since there is no real way to determine how much memorization is beneficial, there is the risk that SuperMemo will dictate what is learned. There might be little material that most people must memorize, with learning the vocabulary of a new language the most obvious exception. The student enamored of memorization technology will be spending his time learning details, not acquiring the ability to determine which details are worth attending to.
Answer:

There is much to remember: There may be little material that people must memorize, but there is a world of material were memorizing things brings benefits that outweigh the cost of memorizing. If the cost of indefinitely retaining a piece of knowledge in memory is 1-4 minutes, the number of pieces of information that could return this investment is greater than lifetime of memorization. Those pieces may range from a useful mathematical formula, through a location of a country on the map, through the name of a carcinogenic dish, to seeming trivia such as … facts about your mother-in-law (Outlook Calendar entry won't let you sneak a compliment at the family table)

Deductive reasoning feeds on knowledge: We have not yet developed a theory of everything or a super-brain that could use it to derive all truths via deduction. Reasoning requires knowledge. Einstein also needed facts and rules developed by his predecessors to arrive at his theories. Even a genius mathematician working in the attic in detachment from reality, will need a few things in his memory to start with (such as a problem to solve in the first place, or a few formulas or theories that will shorten his path to the goal). A physician at the scene of an accident must instantly retrieve seemingly mindless facts from his or her memory such as the name of the drug and the dosage. Relying on deductive reasoning and smarts will not do

SuperMemo provides usability feedback: The central power of SuperMemo is in providing you with full control over what you decide to remember. In addition, incremental reading can serve as a storage of things you care about but not necessarily remember. These storages of things remembered and things that are important provide for immediate associative memory for problem solving on one hand, and a tool for "brainstorming with yourself" and extending knowledge via incremental reading on the other. SuperMemo provides you with a feedback on how knowledge impacts your life. With time, it helps you understand what is worth memorizing and what facts are time wasters. Ignorance may initially tempt you to abuse SuperMemo, but SuperMemo will soon demonstrate which efforts are futile and which bring a palpable benefit. This self-correcting feedback mechanism is a priceless added benefit of getting enamored with SuperMemo.

Not only geniuses use SuperMemo: SuperMemo is used by a special lot of people. Primarily they are a strong-willed and self-disciplined group. Weaker souls drop out very soon. Some may show obsessive and compulsive attitudes and these will backfire. Some may persist for months in a strong belief SuperMemo is the right way to go and still make little progress in areas other than word-pair learning. Like in any group, there are stronger and weaker students. There are crammers and high-fliers. In other words, the uncritical trust in SuperMemo can have negative side effects, but the feedback mechanism mentioned earlier acts as a countermeasure. All in all, with its tangibility and measurability, SuperMemo helps bad students understand their errors. With time, users of SuperMemo show remarkable progress in understanding how their memory works and what the role of knowledge in life is. Bad students will either improve or drop out.

All good things can be used in a bad way: Apart from the side effects of misconstrued memorization, SuperMemo might also be used by a bad lot for their purposes. Hopefully, Osama is too contemptuous of "western" technology to make his Pocket PC repetitions in the cave to extend his knowledge of the best ways of harming his hate targets. But even here we might hope that a dose of extra learning would bring him closer to seeing that what we share is more important than what divides us. 
All innovations and inventions can be put to bad use. Cars kill and pollute. Airplanes can be flown into buildings. TV is numbing our knowledge selection skills. Web was branded "a garbage bin of human knowledge". Even books encourage passive review as opposed to active processing. SuperMemo does encourage memorization and even the most proficient user will memorize some ballast of junk knowledge. What matters is the balance of costs and benefits. The value of knowledge is hard to measure. The lifetime impact of SuperMemo is hard to measure. To ultimately answer the above question we would need an equivalent of the longitudinal Terman Study. Will those kids who contracted the bug of SuperMemo in the early 1990s get bogged down with lifetime of time-wasting repetitions? Or will they become presidents, Noble winners, and great inventors? Time will tell

Is repetition the best way to remember?
(BruceTrek, Sunday, March 10, 2002 7:20 AM)
Question:
Can you send me some links to independent research that shows repetition is the best way to remember?
Answer:
There isn't much research being done currently to show that repetition is the best way to remember. This fact is just taken as true. Similarly there isn't much research done to prove that the brain is the organ where thoughts are born. In the latter case, nearly all neuroscience lives by the brain-mind connection. This does not prevent others (beyond science) to look for mystical explanations to the thought process, emotion, consciousness, soul, etc. As for the repetition, no reputable textbook on the learning methods will deny that "repetitio mater studiorum est". Some researchers in the field looked to confirm the concept of permastore (i.e. lifelong memories), but that effort has not been successful. Some "accelerated learning" companies will try to sell you learning materials and insist that "it is all in mnemonic representation", i.e. you can learn it once (the "right way") and remember it for ever. The best way to disprove that claim is to learn mnemonic techniques, buy those "optimally formulated" materials and learn it with SuperMemo. SuperMemo will measure and prove that well formulated material is indeed remembered much better. But it is still subject to the same old negatively exponential forgetting process that affects all acquired memories (as opposed to innate memories wired into the brain at birth). Today, supermemo.com is probably the only website so heavily focused on the concept of repetition. You will find links to many sites throughout but there isn't one that would particularly attempt to prove that repetition is the key to lasting memories. For every user of SuperMemo, the question on the importance of repetition becomes irrelevant after a few weeks with the program. SuperMemo measures the forgetting rates and graphically illustrates what happens with memories once they are not taken care of

SuperMemo and low self-esteem
(B.B., Friday, October 18, 2002 3:57 AM)
Question:
Memory problems? Oh yes! I am sufficiently working at a very low self esteem not only in English, but also in mathematics. Please tell me in some uncertain way what your software does and how it is going to help me in these two fields of study
Answer:
SuperMemo makes sure you remember what you decide to remember. As long as you show patience and persistence, it guarantees the results. As such, it worked great for people's self-esteem in many cases. However, there are many obstacles on the way. For one, you may dislike the fact that the program seems complex. You may fail to do your daily quota of repetitions. You may fail to formulate your material in a prescribed simple way. As far as English is concerned, you will find it very easy to memorize vocabulary or proverbs or idioms. It will be far harder to learn more elusive things. For example, to make good speeches. Or to recite long poems. Or to debate. Those skill require more understanding of the learning process. As for mathematics, things are even more complex. Without a good manual matching your skills, SuperMemo may appear to be entirely useless. In learning mathematics, the memory is not your main limitation. It is the selection of the material and the way you learn it that will determine your success. In other words, SuperMemo is a sure remedy for memory problems, but it is not a learning panacea. You will find many articles at supermemo.com discussing learning skills such as knowledge formulation, mnemonics, selection of the learning material, etc. See also: Introduction to SuperMemo

Different intervals used in different SuperMemos
(Stracner, Jason, United States, Jul 13, 2004, 06:39:47)
Question:
Why are there different intervals used in paper SuperMemo, SuperMemo for Palm Pilot, SuperMemo for Pocket PC and SuperMemo for Windows?
Answer:
Only SuperMemo for Windows computes accurate intervals that ensure achieving the desired forgetting index (assuming no overload and assuming the learning material is correctly formulated). For technical reasons, other SuperMemos use simplified algorithms (usually based on E-Factors, which lead to minimum computing). In addition, authors of individual SuperMemos often introduce their own modifications to the algorithm (e.g. limits on E-factor change, arbitrary first interval, interpretation of memory lapses, etc.). Paper SuperMemo is the least accurate. It uses fixed intervals for conglomerate pages of items. In such circumstances, it is not possible to differentiate between difficult and easy material. Nor is it easy (or worthwhile) to modify the function of optimum intervals on paper based on the feedback from the learning process

The optimum number of repetitions will depend on numerous factors
(BruceTrek, Sunday, March 10, 2002 7:20 AM)
Question:
Is there any research or general knowledge about the ideal number of repetitions to use when you learn something new?
Answer:
There is no ideal number of repetitions. Depending on the student and the complexity of knowledge, the optimum number of repetitions may vary from a few to dozens in lifetime. For ill-structured knowledge, achieving retention of 90% may be practically impossible. The best research tool here is SuperMemo. Its algorithm will attempt to predict how a single piece of knowledge in your collection will fare. You can peek at Future repetitions field to see how many repetitions are statistically expected within the next 30 years for the selected level of knowledge retention for that particular piece of knowledge

Mid-interval repetitions do not bias your measured forgetting index
(Robert Drózd, Poland, Friday, November 04, 2005 6:16 PM)
Question:
The measured forgetting index is not updated when I mid-review items from the future. For instance when I repeat those items collected with the Filter option. A retention value in the Workload window is updated correctly
Answer:
To prevent improving the measured forgetting index with early repetitions, it is not updated if the repetition occurs before its scheduled date. This selective measurement is not applied to "today's" measured forgetting index nor to the retention data in displayed in the Workload window. Consequently, the latter two may show better readings if you use mid-interval review a lot

Intervals are measured in circadian cycles (#1143)
(Michael M., United Kingdom, Friday, March 04, 2005 10:47 AM)
Question:
It would be a nice option to have intervals calculated in minutes, so that if one first learns an item at say 08:30, it might be re-presented at say 12:15, then 19:45, then the next day at 10:45 etc.
Answer:
Due to the spacing effect, measuring intervals in minutes might be counterproductive. Not only would extra necessary repetitions be needed, but also the spacing effect might be evoked with the resultant decrease in memory stability. The main reason for rounding intervals to days is the memory consolidation cycle measured by waking-sleep rhythms. Although it is recommended to make repetitions at times of peak mental performance, there is little long-term difference between making repetitions in the morning and making them in the evening. In particular, this difference is negligible if you choose one of the two mental peaks of the day: early morning and early evening (the terms "morning" and "evening" are relative and an owl's peak may come at 2 am). If you believe that your items require repetitions that are more frequent than 24 hours, be sure they comply with the rules of formulating knowledge

Could SuperMemo become an unhealthy addiction?
(smmanic, Thursday, July 07, 2005 12:58 AM)
Question:

It seems my entire life is centered on SuperMemo. In making any decision about my life--my choice of job, my choice of transportation means, my choice of social activities--almost invariably I begin with the question, "How will this affect my ability to do repetitions and to add new items?" Clearly I have an obsession with learning and with SuperMemo. My concern, and the subject of my post, is over whether or not this obsession is a healthy one.

In the first six months of using SuperMemo, my focus was strictly on the goal of inputting my total present knowledge (at risk of being forgotten). From a certain perspective, particularly after completing four successful years of college, I am saddened to think I reached that once "monstrous" goal in the space of only six months. Now, after only a year and a half, my collection contains 15,000 memorized items, and my level of knowledge has increased 300%! (That means I feel like I have gone to college three times!) It is a remarkable feeling knowing precisely how much you know.

SuperMemo's instruction manual refers to my database of knowledge as my "collection"; I call it my "brain." My collection is so thorough, it's at least a close replica. With the invention of the thumbdrive, it is humoring to consider that I sometimes wear my brain around my neck!

To be clear, it is difficult to determine whether my present lifestyle is the result of SuperMemo or whether SuperMemo simply fits into a lifestyle I would have chosen for myself anyway. My uncertainty stems partly from the fact that I am a relatively young adult, and like many my age, have never really even begun to settle down into a steady lifestyle and with which I could compare my present "deteriorated" one. (I place that word in quotes because that is how an outsider would likely view it.) Without giving a complete biography of myself, suffice it to say I come from a family whose members all like to move frequently, who tend not to cling too tightly to friends, and whose interests are constantly in flux.

Clearly, SuperMemo is an addiction I cannot shake. The question, again, is whether that addiction is unhealthy and whether I must learn to temper it more. The clichés we throw about would suggest not: knowledge is power and learning what life is all about, right? If the clichés are correct, then anything that helps further my learning is healthy. Perhaps the measure of my obsession's unhealthiness is the extent to which it jeopardizes personal relationships. No, I am not married, but to be fair I have always been somewhat averse to the idea of marriage. I have friends, though my friends have always numbered few. And those relationships I do retain are enhanced, I think, by the increase in confidence and self-esteem attributable to SuperMemo. Despite whatever balance I have managed to maintain, however, I think I would give much of it up if only by doing so could I continue to use SuperMemo. To be sure, knowing now that the program exists, I think if ever I were to lose access to SuperMemo and my collection, I would become suicidal. That is no joke. God, family, and SuperMemo: that is the order of my priorities.

Am I headed for disaster?

Answer:

You might be heading for disaster, but you might also be heading for greatness. It all depends how well you rationalize your attitude and learn to employ new knowledge in accomplishing your goals.

First you might want to figure out if you are indeed dealing with an addiction. Some researchers argue: "No harm, no addiction". However, there might be a neurophysiologic process that may lead to harm in the future. If you were to, as per your own words, become suicidal at withdrawal, you would indeed meet a key criterion of addiction, but your description seems to indicate that you are rather dealing with a variant of a compulsive behavior. You do not mention tolerance (diminishing satisfaction), lack of control, or desire to reduce the addictive behavior (i.e. conflicting rewarding and punishing stimuli). Interestingly, you are definitely not prone to hide your addiction from the world or lie about it. The fact that you posed the question on a public forum might even indicate that, to a degree, you are proud of your attitude (e.g. while mentioning "doing college in 6 months").

Few people realize how powerful a role genes play in behavior. Thus you might be surprised with a claim that your compulsion is quite likely to have a genetic background. You will certainly notice that none of your friends is prone to acquire a similar habit, and that you will find it hard to locate the roots of the habit in your childhood or upbringing (except where personality traits are amplified, e.g. by inspirational tutoring). Compulsive behaviors do run in families. In this context it would be interesting to study your predisposition to other addictions (as these often correlate). However, this should not be a reason to worry per se. Just the opposite. The history of invention and scientific discovery proves that those traits might be responsible for quite a portion of mankind's progress. In the end, your compulsion may be injurious to your own life, and, at the same time, bring immense benefits to others. This has often been the outcome in the life of great inventors or scientists who changed the world while living in utter misery. Unlike animals, humans seem to have strong anti-entropy mechanisms imprinted in their brains. In other words, they tend to marvel over art, music, patterns, structures, models, abstract concepts, beauty of science, etc. Compulsive behaviors may be a strong expression of these mechanisms. You love the fact of being in control over what you learn and that must be rooted in the beauty of building a neat structure of knowledge. The "rage to learn" is one of primary characteristics of gifted children. If you now employ this compulsion to accomplishing lofty goals, greatness is likely to outrun disaster as the likely outcome. In other words, you must resolutely plan against learning for art stake. Instead, your learning, targeted at specific goals, should make up a rational proportion of your time with the rest filled out largely by creative activities targeted at specific productive goals. In Stephen Covey's terminology, you should balance your production to production capacity ratio (P/PC). If you accept well-selected knowledge as valuable you should be able to avoid conflicting stimuli and an internal battle of conscience.

This is an interesting material for more than just an FAQ. It would be nice if you stayed in touch to develop this into a case study.

Bahrick's research on Spanish vocabulary retention does not undermine SuperMemo (#442)
(Desmond Connor, Jan 28, 2005, 9:38:48)
Question:
Isn't the whole concept of SuperMemo a bit shaky in the light of Bahrick's research on Spanish vocabulary (spanning 50 years!). For example: "The analysis yields memory curves which decline exponentially for the first 3-6 years of the retention interval. After that retention remains unchanged for periods of up to 30 years before showing a final decline"
Answer:
Bahrick's research is invaluable as it is quite unique in the field otherwise dominated by research with short-term goals. His results are consistent with the two-component model of memory underlying SuperMemo. What may be confusing at first is that the purely exponential nature of forgetting comes from a model of unitary traces of memory. In real life, memories are always composed of more complex engrams. Moreover, bodies of knowledge are composed of memories that are heterogeneous in that individual engrams differ in their difficulty, stability, and retrievability. Finally, Bahrick's methodology, for obvious difficulty with long-term research (incl. the size of the sample), inevitably carries a substantial margin of error. What may appear as a kinked forgetting curve can well be approximated with a continuous power function that is a result of the superposition of exponential forgetting curves in full agreement with the two-component model of memory.

The forgetting of a language can best be illustrated with the observation that after a course, we usually quickly forget a large body of knowledge. Usually the most difficult and the least rehearsed knowledge goes first. Once this body is eliminated, the cumulative forgetting curve flattens. Now those easier pieces of knowledge and those that have been best rehearsed decline at slower rate. Their individual forgetting curves are much flatter. Overall forgetting is slower. Finally, many years later, only the most stable memories survive. Those may be entirely resistant to forgetting. This does not mean that these are permanent memories. Most often, these are memories that can be refreshed by association: a face of a friend from school, thoughts of youth, an old movie, or a daily ritual. After all, it is quite hard to forget Hasta la vista baby

SuperMemo will not help you bring things to mind without a trigger
(D.M., Jan 26, 2006, 06:54:40)
Question:
How can I use SuperMemo to remember to remember something?
Answer:
SuperMemo will not help you much in bringing things to your mind without a behavioral trigger. It only helps you remember the association between the stimulus and the desired response. It will not help you generate a response without a stimulus. You cannot use it to remember to turn off the gas, unless you associate the turning off the gas with a specific trigger. For example:

Q: What should I always remember about at the time of leaving home?
A: Check if the gas is off

With some training, checking the gas will become a habit. SuperMemo will only ensure that you do not forget about forming the habit

Forgetting is a decay process that can wipe out memories for good
(G.W., Feb 16, 2007, 11:19:34)
Question:
Some psychologists believe that forgetting is not a decay process. Although it may seem a memory cannot be recalled, it is still there. For example, you can recognize an item in a group. Or your re-learning time is shorter. With disuse memories become inaccessible but not gone. Does SuperMemo account for this fact?
Answer:
We need to differentiate between memory stability and memory retrievability to show that memories do fade entirely. Retrievability case is simpler and obvious. Exponential decay is a universal phenomenon in biology and physics. This is how memory retrievability declines. This can be seen in SuperMemo in forgetting curve graphs. Decline in retrievability is responsible for making memories inaccessible at some point. The harder question is what happens with memory stability. The problem is that with decline in retrievability, stability can no longer be measured. Once we lose access to memories, we have no way to test for stability leftovers at the synaptic level. Those leftovers are definitely there. We can see that in spaced repetition. Stability of memories keeps increasing with each review. Even and especially then when the memory is on the verge of being irretrievable. However, the evolutionary purpose of forgetting is to free the storage for new memory traces. Forgetting and spacing effect work together in optimizing the memory storage. If synapses sustained their stability after "forgetting" (i.e. when memories become irretrievable), the brain would gradually lose its original optimization capacity. New memories might become very easy to establish if participating synapses had already been stabilized. That would make the brain a progressively more conservative learning machine. If this "becoming conservative" actually happens in reality, it is more because of previously established memories (i.e. states that involve both retrievability and stability). Not because of the previously established synaptic stabilities alone. 

If there was no decline in stability, you should be able to observe the fact in SuperMemo using the first interval graph (this graphs shows both newly memorized items as well as items that have been re-learned). In a well executed learning process, the length of the first interval keeps decreasing for items with each successive memory lapse. Forgotten items are in no way favored in the process of re-learning. In a vast majority of cases, in a massive learning process, forgetting a simple item will require re-learning as if from scratch. For more complex items, this is less visible, as these are often "partly forgotten" making facilitated re-learning possible. 

Passive recognition is easily explained at the network level. While memories decay, individual synapses may no longer provide access routes to a specific network. In other words, a desired configuration of activity cannot be evoked in active recall. However, passive recognition can still be possible as it may require a tiny subset of original activity to trigger recognition. After all, the recognition stimulus itself provides activations that are able to plug the gaps in memory. Similarly, re-learning of partially forgotten material is explainable by the same mechanism. As long as the portion of the potentiated network is retained, the original configuration of activity can be restored and produce re-learning that capitalizes on previously produced stability of memory traces in individual synapses taking part in the network. However, once the decay process proceeds far enough, neither recognition nor facilitated re-learning will be possible. Memories will be gone for good. 

How does SuperMemo deal with re-learning? It modifies the estimated difficulty of the forgotten item and enters it into the learning process anew. As if never learned before. Measurements show it very clearly, for a simple well-formulated item, forgetting nearly wipes out the benefits of previous learning. If you look at the forgetting curves for re-learned items, they are as steep as for newly learned items. Those items cannot capitalize on previously earned stability. Each time they are re-learned, they form a new pattern of activation. The process of building stability must then begin from scratch.

SuperMemo can lead to learning garbage
(anonymous, Jan 20, 2007, 04:59:15)
Question:
If you learn garbage with SuperMemo, you will waste time on reviewing garbage, and possibly retain garbage in your memory for many years
Answer:
It is true that persistence of memories formed by SuperMemo carries a risk. It is then your sole responsibility to make sure you keep meticulous notes on sources and their reliability wherever your mission-critical information is concerned.

Learning garbage may seem like an anti-thesis of good learning. However, rarely do we face neat textbook information that can serve as model knowledge requiring no verification. In real life, we often face chaos of contradictory information coming from different sources. For example, when working in a fast-growing field of research, you will constantly meet new findings that do not fit old models. Reconciling the chaos of new information may then become your primary preoccupation. Cognitive research shows that our predictive capabilities quickly become saturated with the inflow of additional information. For example, a handicapper may need good information on horses and jockeys to set the odds. However, his accuracy does not improve much once his cognitive capacity becomes saturated. The same extends to other fields where human judgment is involved.

SuperMemo can help you shift the saturation point by making it easier to resolve contradiction. In conditions of low retention, an individual facing contradictory propositions A and B will often oscillate between A and B points. Such an oscillation is a function of exposure over time. However, if you memorize the proposition A, encounter with the proposition B is unlikely to produce such an oscillation. Instead, a red flag will be raised signaling the contradiction. You can then rephrase the question on proposition A to include proposition B with sources and other considerations predicating on validity of A and B. 

By resolving contradictions, SuperMemo helps you built coherent models of reality. These in turn improve your judgment and your problem solving powers.

Still, you need to remain vigilant. When trying to understand the world, you are bound to face information garbage. Paradoxically, learning garbage can lead to the emergence of improved models of reality. On the way towards the ultimate model though you may need to face false information that is often more costly than ignorance. You cannot let your guard down.

Use Simulation to figure out the expected speed of learning (#28256)
(Robyn, Sep 23, 2004, 12:47:42)
Question:
If an individual can commit to exactly 100 repetitions per day, how large will his collection eventually become?
Answer:
You can use Tools : Statistics : Simulation to answer similar questions. For 100 repetitions per day, you will on average arrive at 75,000 items in 15 years. However, this number will vary greatly depending on the difficulty of your material, your mnemonic skills, forgetting index, the use of postpones, etc. If you do not have SuperMemo, you can roughly estimate the number of items by assuming that you can learn 1 new item per 7-10 items repeated per day. Using this method you will expect 55,000-78,000 items memorized in 15 years. Remember, however, that the learning speed is not exactly linear and you will get better results for shorter periods and slightly worse results for longer periods. For more see: Theory

What is better: SuperMemo or VTrain
(Achab, Sep 25, 2004, 16:50:17)
Question:
I found a website that has reviewed many applications similar to SuperMemo and issued a list of the best ones: www.quingle.com/softarea/flash-wi.htm. SuperMemo is placed second along with other programs. Actually, reading the reviews you can see that it somehow rises a bit above the other runners-up. Anyway, the software which is placed first is one called VTrain. According to the criteria of the reviews, the reason why VTrain outsmarts SuperMemo is that you can’t group items by difficulty or priority with SuperMemo, while you can do that with VTrain (using some Leitner Study File system). Do you regard as accurate information the fact that using VTrain you can group items by priority or difficulty while with SuperMemo you can’t do that, or you can do that in a less fine way? If so, do you think you will add this Leitner thing to improve your software?
Answer:
SuperMemo is very strong at prioritizing. Moreover, we are certain that its repetition spacing algorithm is superior as compared with other applications. Moreover, we believe that no better repetition spacing theory currently exists. The Leitner system is a rudimentary spacing algorithm that preceded SuperMemo. It is not targeted at any particular level of knowledge retention, and as such cannot be a viable substitute for SuperMemo. Nevertheless, do not take our word as final. You could best write to SuperMemo Forum at Yahoo eGroups. There you will find many users of SuperMemo who tried VTrain. Many of these will agree with the verdict favoring VTrain. SuperMemo loses ground for its being overly complex and poorly optimized to satisfy a novice user. Many people give up SuperMemo early for the mere dislike of its "repelling" interface. 

See also: http://www.antimoon.com rich in discussions about the best software for learning vocabulary, incl. VTrain (note that Antimoon promotes SuperMemo).

The algorithm used in SuperMemo is not "fixed"
(DaVinci, Oct 04, 2004, 13:20:30)
Question:
SuperMemo is always increasing the intervals at the same rate (given the same series of grades), while FullRecall is smarter and adapts to the learner
Answer:
This is not true. The rate of interval increase is determined by the matrix of optimum intervals and is by no means constant. Moreover, the matrix of optimum interval changes in time depending on user's performance. You may have an impression of a fixed or rigid algorithm only after months or years of use (the speed of change is inversely proportional to the available learning data). This convergence reflects the invariability of the human memory system. It does not matter if you use algebraic or neural approach to the optimization problem. In the end, you will arrive at the spaced repetition function that reflects the true properties of your memory. In that light, the speed of convergence should be held as a benchmark of algorithm's quality. In other words, the faster the interval function becomes "fixed", the better

SuperMemo contributes to rat race! (#1357)
(Beata, Nov 11, 2006, 16:59:16)
Question:
Your article about Tools : Plan is scary! Don't we get enough of rat race and speed. Your tasklists and incremental reading are not any better. I can see there "more, more, more". And where is the place for our humanity? Did you hear of the Slow movement?
Answer:
Paradoxically, Tools : Plan can help you slow down. It is up to you how much you pack into the schedule. The main problem with "living slow" is that you may neglect vital matters that will, in time, cause you more stress and hurry than necessary. If you produce a "slow" schedule with a few minutes for handling vital issues on a regular basis, you are less likely to suffer manic "catch up" due to being "slow". Tools : Plan can be abused, but it can also help you reduce stress levels, slow down and yet ... move on at a steady speed. 

The same refers to incremental reading. Although it may encourage you to import more and more material, it will painlessly remove the excess import from your view. You can proceed at your favorite healthy speed without ever worrying that you missed anything important. You can import everything, and then optimally read and learn only as much as you got time or patience. The entire process is painless. 

Finally, tasklists might belong to the greatest de-stressors of all. Instead of rushing through your to-do list that always grows longer, you can safely focus on top-priority tasks and live with the conviction: "I did not do everything, but at least I did my best". 

All in all, tools offered by SuperMemo can be abused and multiply your stress level; however, when used as designed they are supposed to achieve the exact opposite: maximum efficiency at your chosen speed at minimum stress

Why isn't first repetition followed by interval=1? (#14511)
(Rick Natt, South Africa, Jun 30, 2007, 13:02:38)
Question:
I use SuperMemo mainly for memorizing foreign languages and my mathematics notes. When I learn a new word, how come the first repetition is about 8 days from now? Surely the first repetition should be the next day and only after that should the interval get longer
Answer:
Having intervals of one day would have the following negative consequences: 

1. you would increase your workload 
2. memory imprint produced would be weaker due to the spacing effect 
3. successive intervals would also need to get shorter multiplying the negative effects 

SuperMemo produces intervals that are as long as possible within the limits of your desired level of recall. For example, if you plan to recall 95% of foreign vocabulary, the first interval is more likely to be around 8 than to be around 1.

Your own personalized peg-list would work best (#28726)
(kayla partridge, Thursday, October 07, 2004 5:28 PM)
Question:
I was trying to search for a pre-done peg words set for memorizing numbers. I could not find it in SuperMemo Library
Answer:
If you want to memorize numbers, e.g. phone numbers, a peg-list from 0 to 100 is priceless. However, nothing works better than your own peg-list. For example, if you were born in 1976, you could associate 76 with yourself. That's far easier than associating the peg with Jimmy Carter who was elected in 1976. Choose your own unique pictorials for all pegs and then learn how to build funny scenes of two-digit combinations

Why do synapses get weaker during sleep? (#3224)
(J., Jan 30, 2008, 18:13:11)
Question:
NYT has reported on a research (http://www.nytimes.com/2008/01/29/science/29obslee.html)  that sleep weakens the synaptic strength. At the same time, synaptic strength increases during waking. This seems to go against your own findings that you published on your website that indicate that during the day one's ability to recall facts seems to be waning (http://www.supermemo.com/articles/sleep-research-2007.htm)
Answer:
There is no contradiction between the fact that synapses get strengthened during waking and the ability to recall things drops at the same time. First we need to differentiate between (1) short term increase in synaptic conductivity that is a result of learning, and (2) the ability to recall long-term memories (as they are tested during learning with SuperMemo, which was used to produce the data). 
Secondly, we need to look at the most likely explanation for the weakening recall during waking. The most coherent, attractive and best-supported hypothesis says that the overload of short-term low-interference networks is responsible for a declining capacity of memory during a waking day. This decline cripples the working memory, and in consequence, it affects the entire spectrum of human cognitive capabilities. The main function of sleep would then be to redistribute, reconsolidate and optimize those short-term memories that slow down further learning. To put it metaphorically, the brain is like a computer that keeps loading chunks of data to its memory during the day. As the memory fills up, the computer slows down, and all applications crawl into a halt. However, if you test individual memory cells, you will notice that they strongly cling to their new data. In the night, the computer will gradually organize the chunks of data, remove discrepancies and duplicates, write down memories to the hard disk, and run a defragmentation process for easy and fast access. Both the increase in synaptic conductivity in wakefulness, and the decline of learning capacity during the day are well documented. 
As for the decline in synaptic strengths during sleep, it also fits well with the present models of sleep and learning. One of the main functions of sleep should be to optimize the memory storage. This entails representing memories in most efficient way, i.e. so that they are most abstract, consume least space, generate minimum interference, and so on. That process should indeed result in reducing the overall cost of memories, and result in weakening of redundant synaptic connections.