Spaced Repetition

Theory and Tips

See spaced repetition and the spacing effect on Wikipedia.

Spaced repetition is a popular technique based on research by the German psychologist Hermann Ebbinghaus in the late 19th century. Ebbinghaus discovered the “forgetting curve” and the “spacing effect”.
(See Weibell, C. J.: Memory and Forgetting (Hermann Ebbinghaus - 1885 Principles of Learning, no date.)

Ebbinghaus' findings would later lead to the development of techniques to improve learning. A well-known example is the Leitner system that Sebastian Leitner developed in the 1970s. After computers became mainstream, others came up with electronic versions of this type of flash card system, for example SuperMemo. Spaced repetition programs or spaced repetition systems (SRS) schedule when a flash card needs to be presented again and thereby take some of the hard work required by paper-based systems off your hands.

Many people use flash cards only for vocabulary, although they can be used for any subject that can be broken down into simple question-and-answer format. This includes grammar (e.g. using cloze tests), geography, history, etcetera. Some people mistakenly think that spaced repetition is a language learning method; it is actually a technique that should never be more than a part of the learning process, and most of the learning time should be spent on other activities.

Spaced Repetition Software


Anki is a popular free and open source spaced repetition program by Damien Elmes that is available for Microsoft Windows, Mac OS X, GNU/Linux, BSD, Android and iPhone. The program is based on an older version of the SuperMemo algorithm called SM2. A detailed user manual is available on the website.
The program allows you to created flash card decks and share them with other Anki users on Even though you can use decks created by other people, it is highly recommended that you create your own.
When revising decks, you can customise the settings, for example, how many flash cards should be presented per day, how many new ones should be shown, etcetera.

Other useful links:


Mnemosyne is a free and open source flash card program that works on Microsoft Windows, GNU Linux, Mac OS X and Android. After registering for a free account on the website, you can also share your card sets with other learners. In addition, you can also download scripts and plugins.


SuperMemo is a commercial spaced repetition software for Microsoft Windows. (There are also other versions for Pocket PC and Palm OS, and an online version.) A manual is available on the SuperMemo wiki. The SuperMemo website also contains many useful articles about memory and learning in general. SuperMemo also has a YouTube channel; most of the videos there are in Polish.

Other relevant links:


Gradint is a program written by Silas S. Brown that can be used to make your own self-study audio tapes for learning foreign-language vocabulary. It uses a variant of Paul Pimsleur's graduated-interval recall (which gave the program its name). See Paul Pimsleur's article A Memory Schedule, published in the Modern Language Journal in 1967.
The program is available for Windows, Mac OS X, Linux, Windows Mobile (version 6.0 or earlier), Android, and Risc OS.

Other Flashcard Programs

Articles and Blog Posts about Spaced Repetition

Spaced Repetition in Other Areas

Spaced repetition has also been used for subjects that have nothing to do with language, for example chess.

Ebbinghaus and Other Early Memory Research

This section is temporary and will probably move to a different part of the site.