History of SuperMemo
This text is incomplete. It is being worked on incrementally. Please come back in a few days, or see other texts at SuperMemo Guru
Origins: memory research
- 1885 - Forgetting curve: German psychologist Hermann Ebbinghaus, the pioneer of experimental study of memory, published his Contribution to Experimental Psychology. He used himself as his sole experimental subject. Ebbinghaus' work was very influential (English translation 1913), yet for years it was not followed by similar research of major significance! A myth that can be tracked down to this History of SuperMemo page says that Ebbinghaus invented spaced repetition! Another myth says that Ebbinghaus was first to measure the exponential forgetting curve. The formulas attributed to Ebbinghaus came from SuperMemo (see: Forgetting curve)! Ebbinghaus suggested a negative power curve (such as curve is used for heterogeneous material in Algorithm SM-18)
- 1901 - Spaced review: American psychologist William James suggested that review of the learning material should be spaced in time. Similar conclusions were drawn by Ebbinghaus and Jost. This expanding rehearsal idea was the basis of SuperMemo in 1985
- 1914 - Spacing effect: W. H. Pyle confirmed the superiority of spaced review in typewriter training
- 1932 - Psychology of study: C. A. Mace (1894-1971) hinted on the efficient learning methods in his book "The psychology of study". He mentioned "active rehearsal" and "repetitive revisions" that should be spaced in gradually increasing intervals, roughly "intervals of one day, two days, four days, eight days, and so on". This proposition was later taken on by other authors (including Tony Buzan), but did not permeate into the practice of study. Only a computer implementation of the idea, SuperMemo 1.0, half a century later, opened a way for a wider public to benefit from spaced repetition
- 1969 - Strength Paradox: Robert Bjork (b. 1939) noticed a reverse relationship between the probability of recall and the memory effect of a review. This led to Bjork's theory of disuse (1992) that would distinguish between the storage strength and the retrieval strength (see explanation). The existence of those two memory variables was independently proven in 1988 by Piotr Wozniak on the basis of the properties of memory underlying the concept of SuperMemo (published in 1995), and the precise relationship between the two variables was computed with the help of data obtained from SuperMemo in 2005. As of Algorithm SM-17, the two components of memory for any pieces of knowledge can be inspected by users of SuperMemo
- 1972 - Expanding rehearsal: Sebastian Leitner published "So lernt man lernen". in which he described his Leitner cardbox. The Leitner cardfile technique can be considered a precursor of spaced repetition. Although the timing of repetition in Leitner box is only loosely related to retention levels and is highly affected by the intensity of learning, the technique points to the benefits of the expanding rehearsal in which successive repetitions occur in increasing intervals. The Leitner system appears ineffective in cases when it produces intervals substantially different from those that result in the desired level of knowledge retention. In the 1990s, it was very popular in dozens of flashcard programs for learning languages
1982-1985: Birth of spaced repetition
- 1982 - Active recall: Piotr Wozniak, a student of molecular biology at the Adam Mickiewicz University of Poznan, Poland, became frustrated with his learning progress. Wozniak embarked on a self-study course which would ultimately lead to the development of SuperMemo. He started with an obvious and timeless conclusion that active recall serves memory far better than passive review. As a result, Wozniak (the author of this blog) started writing down all his mission-critical knowledge on paper in a flashcard form (see: True history of spaced repetition)
- 1984 - Minimum information: Wozniak concluded that learning proceeded much faster if knowledge was split into a number of simple questions and answers reviewed independently. This conclusion was later formulated as the minimum information principle, which is now considered part of the definition of the SuperMemo method (better known as spaced repetition). This is similar to terms such as chunking, atomic learning or micro-learning. However, in SuperMemo, minimum information principle is taken to the extreme: "make it as atomic as possible"
- 1985 - Spaced repetition: Unaware of the previous work in the field, yet using experimental methods first applied by Ebbinghaus a century before, Wozniak designed two simple experiments on his own memory and found how review intervals influence recall. He formulated the first spaced repetition algorithm that would later named SuperMemo. His learning with the new method started on August 25, 1985. This day marks the birth of computational spaced repetition, i.e. the technique in which knowledge is reviewed in optimum intervals that are determined by a computer with the goal of reaching a desired level of knowledge retention. For a detailed description of the first algorithm see: Using SuperMemo without a computer. See: The birthday of spaced repetition: July 31, 1985
1987-1990: Birth of SuperMemo
1987
- Dec 1987 - Spaced repetition software: Piotr Wozniak, now a student of computer science at the University of Technology in Poznan, wrote his first computer program employing spaced repetition. In 16 evenings, he came up with a very simple SuperMemo 1.0 for MS DOS (written in Borland's Turbo Pascal 3). The first computer algorithm introduced the concept of E-factor (i.e. the number that makes it possible to differentiate between items of different difficulty). Wozniak begun repetitions with SuperMemo 1.0 using his human biology learning material on December 13, 1987. Wozniak's spaced repetition algorithm, opened to the public, was later used by dozens of popular learning applications such as Mnemosyne, Anki, and others. This is how SuperMemo 1.0 looked like:

Figure: SuperMemo 2.0 for DOS (1991). The original SuperMemo 1.0 from 1987 looked identical, but was developed on a black-and-white display. The text about Piotr Wozniak and SuperMemo World was added in 1991 when releasing SuperMemo 2.0 as shareware. The name SuperMemo was first used on Apr 27, 1988. Tomasz Kuehn proposed a different name for the program: CALOM
1988
- Tomasz Kuehn from University of Technology in Poznan wrote SuperMemo for Atari ST (Pascal)
- Przemyslaw Glowacki from University of Technology in Poznan wrote SuperMemo for Atari XL (Basic)
- The name SuperMemo was first used on Apr 27, 1988. Earlier in 1988, Tomasz Kuehn proposed a different name for the program: CALOM
- SuperMemo 2.0 was written during summer vacation (Turbo Pascal 4.0)
- SuperMemo 3.0 was completed in October 1988. It used an up-to-date DOS interface with pull-down menus
- SuperMemo gradually gained popularity at Adam Mickiewicz University of Poznan, and the University of Technology in Poznan, Poland
- In an article that would make part of his Master's Thesis, Wozniak demonstrated the existence of the two components of long-term memory. The terms retrievability and stability were proposed (analogous to retrieval strength and storage strength in Bjork's new theory of disuse). The two variables of memory would underlie future Algorithm SM-17 (2016)
1989
- Tomasz Kuehn made the first attempt to commercially sell SuperMemo. His advertisement in Polish computer journal Komputer (later PC World Komputer) sold 10 copies of SuperMemo 2.0
- SuperMemo 4.0 was completed in February with the learning algorithm based on computing the matrix of optimum intervals
- SuperMemo 5.0 in October made another step in improving the learning method. It used an algorithm based on computing the matrix of optimal factors
1990
- Under the supervision of Prof. Zbigniew Kierzkowski, the Head of the Computer Science Department, Piotr Wozniak wrote his Master's Thesis: Optimization of learning. A new approach and a computer application. This 200-pages dissertation was entirely devoted to theoretical aspects of SuperMemo, described the evolution of the learning algorithm, included the model of intermittent learning, and presented the author's optimistic vision of future applications
1991-1995: Origins of SuperMemo World
1991
- July 5, a commercial company, SuperMemo World was formed by Piotr Wozniak and his friend and fellow graduate Krzysztof Biedalak. The real capital: one 80286 personal computer. The goal was to commercialize SuperMemo
- SuperMemo 2 was released as freeware
- SuperMemo 6.0 was completed with the learning algorithm based on the approximation of forgetting curves
- September, Dr Janusz Murakowski joined SuperMemo World
- November, SuperMemo 6 became a finalist of Software for Europe 1992 Award Competition
1992
- January, Marczello Georgiew and Tomasz Kuehn joined SuperMemo World
- February, Andrzej Horodenski from Computer World initiated commercial sales of SuperMemo 6 by writing the first ever article about the SuperMemo method and software
- March, SuperMemo World displayed its products at CeBIT 1992
- September, SuperMemo 6 received the first-degree award at Softarg 1992, Katowice, Poland
- September, SuperMemo 6 received a special award of the Polish Computer Science Society
- December, SuperMemo World turned its first quarterly profit
- December, SuperMemo 6 was awarded in Product of the Year 1992 competition organized by PC Kurier, Poland
1993
- January, after long months of programming, SuperMemo 7.0 was released. It was one of few Windows software products in Poland at that time
- March, SuperMemo 5 was released as freeware
- March, German Chancellor Helmut Kohl came to the stand of SuperMemo World during CeBIT 1993
- May, SuperMemo 7.2 Audio Visual for Windows was released. This was the first SuperMemo able to play sounds and display pictures
- August, written by Krzysztof Wojcieszek, SuperMemo 1.0 for Amiga was released (see video)
- September, SuperMemo topped charts of best Polish software applications for Amiga (Amiga Magazine)
- September, SuperMemo 7 was awarded at Softarg 1993, Katowice, Poland
- December, SuperMemo became the first ever Polish software reviewed in Byte International (update 2024: probably a wrong date, here is only a SuperMemo advert)
- December, SuperMemo 7 was awarded in Product of the Year 1993, PC Kurier, Poland

Figure: Krzysztof Biedalak explains the principles of SuperMemo to Chancellor Helmut Kohl of German; Hannover, CeBit 1993
1994
- January, SuperMemo was voted 4-th most popular Polish software by readers of Polish PC World (behind anti-virus and word-processing products)
- March, SuperMemo for Amiga was voted the Product of the Year 1993 among Polish software for Amiga by readers of Amiga Magazine
- March, SuperMemo World displayed SuperMemo 7.3 at CeBIT 1993
- March, SuperMemo was awarded for the best value/price ratio by the CENA/VYKON journal, Czech Republic
- May, SuperMemo 7 was awarded a prestigious Gold Medal at Infosystem Computer Fair in Poznan
- July, 10,000-th copy of SuperMemo was sold
- August, SuperMemo USA, Inc. publishes SuperMemo 7.4 on CD-ROM, including the audio version of Advanced English best-seller. This title became the first ever Polish Windows software title released on CD-ROM
- September, SuperMemo World was granted the special award of the fair's president, and received a free display at Softarg 1995
- September, SuperMemo World signed its first OEM bundling deal with JTT, the second largest computer-maker in Poland
- October, SuperMemo 7.2 topped the ranks of best-selling software sold on illegal software market, ahead of Microsoft Word 6.0 and Microsoft Works 3.0 (PC World Komputer, Vol. 11, 1994)
- December, SuperMemo for Windows received the Reader's Choice distinction from PC World Komputer (Vol. 12, 1994) by being voted second most popular Polish software in Poland and the most popular Polish Windows software in Poland
- December, Piotr Wozniak completed his Economics of learning. This doctoral dissertation was entirely devoted to the SuperMemo method and outlined the theoretical basis for future SuperMemo. The concept of Knowledge Machine was an inspiration for incremental reading
1995
- January, SuperMemo 6 for DOS was released as freeware
- February, SuperMemo received a positive review in the most prestigious European computer journal: German Chip
- March, SuperMemo 1.0 for Macintosh was released (this version was later discontinued due to low profitability)
- March, SuperMemo World displayed its Multilingual SuperMemo 7.5 CD-ROM at CeBIT 1995
- April, Polish Prime Minister Waldemar Pawlak bought a copy of SuperMemo for personal use (he refused a free gift)
- April, SuperMemo User Survey revealed that users of SuperMemo consider the program their single most important application!
- April, SuperMemo World signed a comprehensive OEM deal with Optimus, the greatest computer-maker in Poland
- May, 30,000-th copy of SuperMemo was sold
- May-Sep, for 100 days, on a creative vacation in the mountains, Piotr Wozniak worked over the outline of Algorithm SM-8 and the outline of future SuperMemo for Windows that would involve multimedia and originate incremental reading (see: First data-driven spaced repetition algorithm: Algorithm SM-8)
- September, 500 beta-testers received Pre-Release CD-ROM with the first hypermedia SuperMemo codenamed Genius: precursor of SuperMemo 8.0
- November, SuperMemo World became the first Polish company ever to display its products at Comdex in Las Vegas

Figure: Marczello Georgiew, SuperMemo World, at Comdex 1995 (Las Vegas)
1996-1999: Origins of incremental reading
1996
- January, SuperMemo was voted the best Polish application by readers of PC World, Komputer
- January, first SuperMemo hypermedia CD-ROM title was released: Video English (with Genius 1.0, early precursor of SuperMemo 8)
- June, SuperMemo Corporation was incorporated in the US with a goal of making it the first company of Polish origin on NASDAQ. The company came close to securing substantial venture capital but ultimately closed
- September, SuperMemo World released a hypermedia best-selling course of English on CD-ROM, Cross Country (with Genius 2.0, a precursor of SuperMemo 8)
- September, precursor of SuperMemo 8, Genius 2.0, received its first award as the hypermedia authoring tool at Softarg 1996, Poland
- October, 60,000 readers of Chip in Poland received a CD-ROM with the full version of the hypermedia authoring SuperMemo (Genius 2.0). Free!
- November, the first Polish multimedia encyclopedia on CD-ROM was released by PWN with SuperMemo as an integrated tool for learning selected encyclopedic material (see: version 2010 with SuperMemo UX)

Figure: A CD-ROM with "Cross Country" course of English with "hypermedia SuperMemo" codenamed Genius 2.0, a precursors of SuperMemo 8
1997
- January, SuperMemo World, Polish veteran of CeBIT and the first Polish company present at Comdex made a strategic turn towards the Internet away from major software fairs. SuperMemo Website at supermemo.com will become SuperMemo World's best marketing tool ever. This also marks the beginning of the accelerated expansion of the concept of spaced repetition around the world!
- January, Polish PWN Encyclopedia with SuperMemo was voted the best Polish software product by readers of PC Kurier
- February, SuperMemo 8 entered beta-testing. For the first time, beta-testing was run exclusively over the Internet with a dramatic impact on program's reliability
- May, over 100 international beta-testers submitted their final reports via the Internet. This SuperMemo 8 beta-testing program alone brought more valuable data than testing programs before
- May 12, SuperMemo World released Deine Chancen in Deutsch with SuperMemo 8 (first commercial CD-ROM with hypermedia SuperMemo)
- June 12, for the first time ever SuperMemo was made available for download from the web
- October 22, 80,000 readers of Chip in Poland received a CD-ROM with SuperMemo 8.0 (Free!) and a demo of Advanced English 97
- November 10, Advanced English 97 with SuperMemo 8 was released
1998
- January 14, SuperMemo 8 was chosen the Product of the Year 1997 by journalists of a respected Polish journal PC Kurier (ahead of MS Internet Explorer 4.0PL)
- March 20, SuperMemo Library hosted by Michal Hejwosz and Piotr Maksimczyk was inaugurated
- May 25, SuperMemo World signed a licensing and distribution contract with Vulcan Media. By September 1998, the two companies will develop the largest network of sales representatives in Poland covering virtually all software resellers in the country
- August 1, SuperMemo World as the first company in Eastern Europe opened an e-commerce store at Yahoo Stores (later SuperMemo Store)
- September 28 - SuperMemo 9 was released
- November 27 - SuperMemo 9 was featured among the most successful Delphi applications
- December 1 - for the first time SuperMemo appeared on a DVD. It was part of the best-selling Polish Multimedia Encyclopedia (PWN, 1999 Edition). This title sold 45,000 copies in the next two years
1999
- April 26, 300,000 copies of Easy English CD-ROM were released in Poland. This was the largest run of SuperMemo up to that time
- May 10, SuperMemo MegaMix 99 was released with 319 SuperMemo collections written by users of SuperMemo
- July 5, on the 8th anniversary of SuperMemo World, 1,000,000th CD-ROM with SuperMemo has been produced
- September, SuperMemo for Windows CE was released
- October 4, SuperMemo 99 introduced a new concept: the reading list. Reading lists extend the application of SuperMemo to the area of knowledge acquisition, selection, prioritization, and formulation. The reading lists later evolved into incremental reading
- November 23, in its greatest success ever, SuperMemo was nominated as the Product of the Decade by PC Kurier, Poland (among four contenders)
2000-2010 Maturation of incremental reading
2000
- January, SuperMemo for Windows CE received Real Mobility Award
- March, SuperMemo for Palm Pilot was released (the best-selling standalone SuperMemo ever)
- July, SuperMemo World and the Internet Investment Fund, signed an agreement on the development of a system for Mobile learning, which later evolved into supermemo.net and ultimately into supermemo.com
- November, SuperMemo 10 introduced the concept of incremental reading that makes it possible to read thousands pf articles in parallel. This is probably the single most important development in the history of SuperMemo since the invention of spaced repetition (1985)
- December, Polish Orthography SuperMemo CD-ROM was listed among the recommended educational tools by the Polish Ministry of Education
2001
- supermemo.net became the first web-based SuperMemo (later to become supermemo.com)
2002
- SuperMemo 11 adopted HTML as the default format in incremental reading (previously RTF)
- Heuristics used to estimate the magnitude of the spacing effect (e.g. in mid-interval repetition), in Algorithm SM-11, were the last major improvement to historyless spaced repetition algorithms
2003
- SuperMemo CE is positively reviewed in Pocket PC magazine, which results in a spike in sales
2004
- May, SuperMemo for Pocket PC became the first SuperMemo to adopt the new XML data exchange format
- September, SuperMemo 12 adopted the XML data exchange format (see: Revolution in the pocket)
2005
- Jan, The battle between the concepts of free running sleep and polyphasic sleep begun (see: Science of polyphasic sleep). Years later, polyphasic sleep will fade into oblivion
- March, First SuperMemo DVD: Extreme English combined the most popular learning material, Advanced English, and the most widely distributed SuperMemo: Multimedia SuperMemo
- May, SuperMemo 9 for Windows was released as freeware
- Sep, Inconspicuous and simple invention: priority queue would transform incremental reading into a strategy with no limits on the volume of the learned material. Users of older versions of SuperMemo will generate their priority queues using a heuristic based on A-Factors and the forgetting index
2007
- March, SuperMemo 13 has been released. Two decades after disk space limits prevented SuperMemo from collecting full repetition histories, at the urging of Dr Janusz Murakowski, full record of repetition timing returned to SuperMemo. This will lay the foundation for the optimization of learning with SleepChart, as well as the Algorithm SM-17
2008
- April, Gary Wolf of Wired Magazine published a 7-page article on the history of SuperMemo: "Want to Remember Everything You'll Ever Learn? Surrender to This Algorithm" (see: audio by Palace)
- December, a contract with the Polish Ministry of Education brought SuperMemo to 144,000 computers in Polish schools
2009
- March, SuperMemo 14 incorporated SleepChart and become the first application to align sleep and learning data. This allowed for optimizing the timing of sleep and enhancing learning in reference to the circadian phase. SuperMemo thus entered a long road towards the future in which sleep can be optimized for the sake of learning, while learning can be optimized with the view to the timing of sleep. The bridge between the two worlds initiates a process in which truckloads of data are being generated for investigating the relationship between sleep and memory. See: Poor sleep = Poor learning
- September, SuperMemo 14 introduced the concept of incremental video, which is an extension of incremental reading into the world of video. This opened a way to handle thousands of YouTube videos without getting lost and without missing a beat
- December, releasing SuperMemo for iPhone
2010
- May, sleep data collected with SuperMemo SleepChart was instrumental in building the strongest case against the polyphasic sleep to date
Later years: Veteran company
2011
- Apr 24, 2011: SuperMemo 12 becomes first freeware to support incremental reading
- July 5, SuperMemo World celebrated its 20th birthday. Major festivities took place, with many distinguished guests, on Oct 4, 2011
- Aug, Algorithm SM-15 in newly released SuperMemo 15 is the last historyless spaced repetition algorithm before Algorithm SM-17

Figure: 20th anniversary of SuperMemo World, 2011
2012
- September, with T-Mobile, SuperMemo World launched the greatest advertising campaign in its history
- December, SuperMemo World opened SuperMemo Language Center in Poznan, Poland. The school provided a unique guarantee: "if fail your target exam, you can claim your money back!"
2013
- Nov 20, SuperMemo 16 released. The vision of Knowledge Machine described two decades earlier became reality
2014
- Jan, supermemo.com takes over as a central on-line product (succeeding supermemo.net)
- March, SuperMemo World opened a new field in education: EduAction. The interactive movie Olive Green combines entertainment, with a course of English and the SuperMemo method. Over the next 2 years, the movie will have collected dozens of awards from journals and movie festival reviewers
- November, multimedia version of Advanced English turned 20 years old. It keeps evolving. This best-selling learning material has always been the fastest path towards acquiring native English vocabulary. Its 2014 release reflected dynamic changes in English and improved item formulations with the view to maximizing their mnemonic power

Figure: Chartlotte Beckett and Krzysztof Biedalak on the set of Olive Green
2015
- April, the model of two components of long-term memory has spawned a new approach to spaced repetition with a new spaced repetition algorithm: Algorithm SM-17. Despite prior claims, the new algorithm has a major impact on the speed of learning, esp. in intermittent learning where review may frequently be advanced or delayed. By mid 2016, the algorithm met all metrics in flying colors
2016
- May, SuperMemo 15 becomes freeware
- May, SuperMemo 17 uses Algorithm SM-17 (in parallel with Algorithm SM-15 to collect comparison metric data)
- May, SuperMemo 17 pioneers the concept of Neural creativity. This new cognitive strategy helps you simulate the process in which a creative brain comes up with solutions to problems. Like a working human brain in slow motion, SuperMemo can bring up related pieces of knowledge, and produce an artificial "train of thought". See how neural creativity came to be
2017
- SuperMemo Guru wiki was setup for the sake of writing an e-book: Problem of Schooling (it later became a central blog of SuperMemo Research)
2019
- May 1, SuperMemo 18 added minor improvements to the Algorithm SM-18 algorithm and the looks
2020
- 100 bad habits learned at school is an effect of collecting honest testimonies from (recovering) students who lost their joy of learning at school
2021
- Exactly 20 years after the decision to bank on Internet Explorer in incremental reading, SuperMemo made a new bet on Edge and Chrome
2023
- SuperMemo 19 was finally freed from the dependence on Internet Explorer. It supports imports from Edge and Chrome.
2024
Further reading
- History of spaced repetition
- SuperMemo for Windows year by year
- SuperMemo News 1997-2001
- SuperMemo News 2002-2017
- History of SuperMemo (source materials for this file)