Regarding "Spaced Repetition"

It is widely recognized that repetition improves learning speed and long-term retention. If you are looking for ways to memorize more effectively, you may be wondering how you can use repetition strategically to maximize these benefits. Consider the following suggestions:

• Your repetition method should focus on optimizing the order in which flashcards are presented for review, rather than try to decide the particular points in time at which cards are presented.


• The method should not be enforced through an automatic card scheduling algorithm, but should be implemented by you yourself through making active decisions about card order during the course of your study.

Optimize Card Order, not Review Schedule

Suppose you are studying 3 cards: "Dog", "Cat" and "Mouse". There are two ways in which you could try to optimize the way in which these cards are presented for review:

1. Optimize the order of the cards in your queue, for example by deciding that the ideal order of your next five interactions with the cards should be:

   Dog > Cat > Mouse > Dog > Mouse

2. Optimize the particular points in time for which reviews are scheduled, for example by deciding that the ideal schedule for your next five interactions with the cards should be:

   Dog: Monday 10:31am > Cat: Monday 11:57am > Mouse: Wednesday 3:40am > Dog: Thursday 10:51pm > Mouse: Saturday 4:36pm.

Optimizing the order in which flashcards are reviewed is without question indispensable for efficient memorization. Using the Leitner system to prioritize difficult cards over easy ones is arguably the single most effective technique you can use to successfully memorize large amounts of information.

An entirely different question is whether it is also beneficial to try to optimize the particular points in time at which a given flashcard is reviewed.

Some theories of memory suggest that there is a benefit in optimizing the timing of review. For example, you may have heard of the "Ebbinghaus forgetting curve", which describes the decay of memory of an item over time. Based on this, you could hypothesize that the time at which a flashcard should ideally be presented for active recall is the time at which the memory trace of the relevant item would otherwise, according to the curve, decline below a certain level. This is one possible conception of the optimal time for reviewing a card.

However, whatever the conception of optimal timing, there are certain practical disadvantages that should be considered in trying to schedule flashcard reviews for particular points in time:

• To be able to review flashcards at particular times that have been set in advance, you must commit to a rigid study schedule. This may be impracticable in light of your other daily activities. For example, if your theory of repetition tells you to review cards on Monday and Wednesday but, due to your job, you do not have time for flashcard study until Sunday, you will simply not be able to adhere - not even approximately - to the prescribed schedule and thus not reap the ostensible benefit of optimal scheduling.


• Trying to adhere to an inflexible review schedule can be burdensome and may negatively impact your motivation and commitment to your study over the long term. Forcing yourself to study on a schedule that does not easily fit with your daily routine may lead you to study at times when you are distracted or tired, and to not take advantage of natural opportunities to study when you have downtime (e.g. while riding the bus or waiting in line at the supermarket). An overly rigid schedule may also lead to a sense of failure if you are unable to adhere to the study regimen you had set for yourself, which could ultimately increase the likelihood of your giving up on your study altogether.


• The theory of memorization used to devise your review schedule may be incorrect, or may not apply to your particular circumstances or cognitive makeup. There is no general scientific consensus on the specifics of an optimal review schedule, and a flawed schedule may impair your performance and slow down your progress. For example, suppose you are studying 300 cards and your theory of optimal timing tells you that, in order to achieve proficiency, you should perform 40 reviews per day over a 30-day period. Suppose, however, that the theory is incorrect and that it would have been possible for you to achieve greater proficiency by performing 150 reviews per day over a 7-day period. Adhering to the flawed review schedule would unnecessarily delay proficiency by 23 days and result in a lower degree of proficiency than you could otherwise have attained.

For these reasons, students are well-advised to not uncritically rely on study methods that seek to schedule card reviews for purportedly "optimal" points in time, and instead focus on the more tractable goal of optimizing the order in which cards are queued for review.

There may ultimately be room for incorporating some time-based methods into your study, such as performing refresher reviews of already-known cards at increasing time intervals to take advantage of any potential "spacing effect", but only if it is clear such methods do not distract or otherwise negatively interfere with your study.

Against Automatic Scheduling

There are two ways in which you can try to ensure that the order in which flashcards are presented for review maximizes the benefit that can be obtained from repetition.

Your first option is to rely on an automatic card scheduling algorithm of the kind commonly used in spaced repetition system ("SRS") flashcard software. The second option is for you to actively decide yourself the order in which you want cards to be presented.

Apart from convenience, the main reason for using an automatic scheduling algorithm would be that you believe that the algorithm is superior to your own judgment in deciding the optimal order in which cards should be presented. However, there are reasons to think that such a passive "algorithm-knows-best" approach will in practice be less than ideal, and that determining card order based on your own judgment will lead to better study outcomes.

This is because the amount of relevant information that is available to you as the actual student greatly exceeds what is available as input to a card scheduling algorithm. Typically, the data that such an algorithm can take as input will be limited to your review history, i.e. data about the points in time at which you previously reviewed your cards and the outcomes of these reviews. In reality, there are many other factors that should be taken into consideration in determining the optimal order of review, including:

• The inherent difficulty of the information on each of the cards. For example, it is arguably easier to remember the Japanese word for "introverted" than the Japanese word for "homeostasis", and you may find it more efficient to prioritize the easier word in the order of review.


• The degree of inter-relatedness of the information on the cards. It may, for example, make sense to schedule cards from the same subject matter area (e.g. "car", "train" and "airplane") in proximity to one another to exploit synergies that arise from studying related material.


• Your subjective level of interest in the information on a card and its relevance to your daily life. You may, for example, want to prioritize vocabulary words that you feel particularly excited to learn or that relate to your profession, because you find that doing so increases your motivation.


• The frequency with which you are exposed to the information on a card outside of your study. If you constantly encounter a word you are studying in your everyday environment, you may want to de-prioritize this word and focus on other words that you are less likely to absorb organically from everyday exposure.


• Factors that affect your capacity for studying at a given time, such as amount of sleep, level of stress, ability to concentrate and external distractions. For example, at times when you are sleepy or your surroundings are noisy, you may decide against taking on cards that are new and difficult, and instead do refresher reviews of less demanding cards that you already know well and that require lesser focus.

These points illustrate that there are many non-quantifiable factors specific to a student's circumstances which are relevant to determining the ideal order in which cards should be reviewed. An automatic algorithm that considers only the times and outcomes of previous engagements with the cards at the expense of other factors can easily result in a flawed review schedule, which can lead you to use your study time inefficiently and slow down your progress.

Software Tools

If you are currently relying on SRS software that uses an automatic card scheduling algorithm, you should consider whether this algorithm really succeeds in presenting your cards in an optimal order, or if it forces you to spend too much time on cards you already know or that have low priority for you, and too little time on cards you really need to focus on.

If you find that you are relying on a flawed algorithm that gets in the way of your performance, you should consider switching to a software tool that does not force an automated review schedule on you but instead provides a framework within which you yourself can decide how you want to queue your cards. Such a framework should provide detailed, easily interpretable information about the history and current state of your flashcard deck, as well as an easy mechanism to utilize this information in selecting cards for your next review session.

Mindframes Flashcards is designed to provide such a framework. The matrix-style card selection screen ensures that you always have information about your prior study history, test outcomes and the current distribution of your cards across the 5 proficiency levels at your fingertips. The color-coding to indicate "card urgency" based on various selectable metrics and the ability to divide your deck into sets of any size, combined with the ability to select cards by set and proficiency level in any combination you choose, provides you with fine-grained control over which cards to include in your next review session.