Why Anki?

People forget things. It's natural, as our memory capacity is not infinite. Every day our brain is bombarded with thousands of pieces of information, and our brain is forced to discard a lot of the information we receive. Most people can't remember what they had for breakfast last Tuesday. This is usually a good thing, as last week's breakfast is not something which is useful to remember.

The problem is that the brain is not so good at deciding what information is important and what is not. Big events tend to be more memorable - a traumatic experience, turning 18, one's wedding day. But smaller pieces of information tend to get discarded just as rapidly as last week's breakfast.

Studies have shown that 48 hours after a study session, we have generally forgotten 75% of the material. When undertaking something that requires a lot of memorization, such as studying a new language, forgetting 75% of the material you learn can be very demotivating.

Spaced repetition

Our brain may not be so good at picking what new pieces of information will be important, but it does eventually catch on. Being placed in a situation where you are forced to recall a recently learnt piece of information, the brain realises that perhaps this information is important, and strengthens the memory. A memory which lasts two days becomes stronger and may last for a week or two next time. If we study it again before we forget, then the memory gets longer again.

This is the key point of spaced repetition: each time we review a piece of information, our memory becomes stronger and we remember it for longer. The first couple of reviews may be a few days or a few weeks, but the more we review, the longer the interval (or space) between revisions becomes. It's not unusual to reach repetition times of 5 years within 10 repetitions - this means that you only have to practice a word once every 5 years in order to continue remembering it!

Forgetting

Of course, even with optimally spaced repetition times, it's natural that some pieces of information will be forgotten. They may be harder to remember because they are exceptions to the rule, or they are pretty different to things you have learnt before. Difficult pieces of information require more regular repetitions at shorter times in order to learn them well.

Review was traditionally difficult

Even armed with the knowledge that reviews at increasing periods of time are the best way to remember, it can be difficult to implement in practice. In the days before computers, people were limited to pen, paper and paper cards called flashcards. The traditional method was to write some facts on a bunch of cards, look at each card in turn, think of the answer, then turn the card over.

There are a number of problems with this approach. One is that easy facts end up being repeated just as often as difficult facts, which means either you're not reviewing the difficult facts enough, or you're reviewing the easy facts too often. Either your time or memory suffers.

Another problem is that deciding when to next review the cards is very difficult. Should you practice the next day? Every day for a week? Once a week for 4 weeks? It wasn't clear how best to approach it.

Along came a guy called Sebastian Leitner, a German scientist who wrote a book on learning and memory. He popularized a new method of studying flashcards. A box is divided up into a bunch of compartments, usually 5. Each compartment represents a different ease level. When you remember a card correctly you move it to the next compartment. If you forget, you move it back to the start.

The Leitner flashcard system was a considerable improvement over reviewing flashcard decks from start to finish, but it was also a bit cumbersome. This coupled with the fact that making flashcards by cutting up pieces of paper is time-consuming has ensured that flashcards remain relatively unused in study today.

Along come computers

With the advent of computers, suddenly the arduous task of making pieces of paper and deciding when to study next went away. These days many thousands of different flashcard programs can be found on the internet. The vast majority of them implement either the most basic flashcard model (drill deck from start to finish), or implement the Leitner system, as it is easy to program and moderately effective.

Yet even though there are thousands of flashcard programs out there today, they are rarely used, and when used they are usually used in the short term to learn some new facts, and aren't used to actually retain information.

Memory misconceptions

Most people don't know how to study, or how memory works. It's not their fault - we spend our early childhood absorbing information without ever worrying about forgetting things, we cram for tests in our upper school years, forgetting everything a few days later. By the time we've finished high school or a university degree, we don't know much more about long term memory than we did when we came into the world.

This results in a lot of frustration for those doing their best to learn. Many students of foreign languages complain that their memory is bad, due to getting old, genetics or other factors. Age does play a part, but the reason they forget so much is not because they are old, but because they never give their brain a chance. Likewise many younger people walk away from learning a new language for the same reasons - the lack of progress and forgetting as much as is being learnt takes its toll.

Why Anki?

I was first introduced to the idea of spaced repetition about 6 months ago. At that point I had been studying Japanese for 2 1/2 years, with short bouts of motivation between longer periods of little to no study. Every time I picked up my textbooks again I found myself getting stuck on the same words that I'd invested effort into learning during the previous study session. The prospect of learning a foreign language was exciting, but the seemingly insurmountable amount of work required and lack of progress soon had me taking another break.

A friend had written a pretty functional spaced-repetition implementation and recommended it to me. After a few days of using it, it rapidly became apparent that this approach to learning and remembering was orders of magnitude more effective than anything I'd tried before. My studying motivation picked up again and I started to look into making the flashcard program available to the students I teach English to, and the people around me who study Japanese.

In the past 6 months, Anki has evolved from a few interface additions to the original flashcard program, to a suite of tools including a desktop program, website and cell-phone access. My goal is to make spaced repetition review (and all the benefits that it entails) available to as many people as possible, so that their studies may benefit as mine have. Please, give it a try!

Thousands of hours of work have gone into developing and supporting Anki. Please consider supporting the author so that Anki can continue to improve.