Thursday, 16 April 2015

How Does Lexicum Reviewing Mechanism Work?

In order to remember any new word you encounter when you learn foreign language you must refresh it periodically. Let’s say that you hear the following word in French: “aneth” (dill). If you don’t use this word in any way you are very likely to forget it soon. If, however, you encounter and use this word over and over, for example because you might enjoy cooking or you happen to like this particular spice a lot, then obviously you will retain this word in your brain for much longer.

The more often you encounter a certain word the less often you will need to refresh it to make it part of your active vocabulary. However, even the most familiar words can be forgotten if they are not refreshed or encountered for a long period of time. For instance, it is not uncommon that people who move to live or work in another country for a long period of time start speaking their first language less well. The same applies even more when it comes to learning new words – once you stop using them they start to quickly fade away until their meaning is completely forgotten.

Spaced Repetition & Leitner System

We didn’t hesitate at all when we chose spaced repetition to implement as a review mechanism for Lexicum’s flashcard-like quiz. Spaced repetition is a learning technique that incorporates increasing intervals of time between subsequent reviews of previously learned material in order to exploit the psychological spacing effect.

There are many spaced repetition systems but we chose to use the Leitner system. It is widely used method of efficiently using flashcard, created by the German science journalist Sebastian Leitner in 1973. Based on what we know about spaced repetition and Leitner System we created Lexicum’s reviewing mechanism in the simple form of quiz.

How Does Our Reviewing Mechanism Work?

Lexicum’s algorithm works as follows – all the new words you add have 7 stages of learning. Every time you start a quiz you have to mark the words that appear, according the level of difficulty – “easy”, “fair”, “hard” or “didn’t know”. In the beginning every word is in stage 1, or in the first group. If you don’t have any trouble recalling the word’s meaning you click on “easy” button and the word goes 2 stages forward. If you hit “fair” the word moves 1 stage forward. Other two options take the word back.

The word is considered learned, when it ‘s being moved at least at stage 6. The specific thing in this method is that when you move a word forward, it appears less often in the following quizzes. In other words, you review the words you don’t know at all more frequently, than words you know better. The intervals of repetition are as follows:

  • Stage 1: The word appears in a quiz immediately
  • Stage 2: The word appears in a quiz after 1 day
  • Stage 3: The word appears in a quiz after 3 days
  • Stage 4: The word appears in a quiz after 1 week
  • Stage 5: The word appears in a quiz after 2 weeks
  • Stage 6: The word appears in a quiz after 1 month
  • Stage 7: The word appears in a quiz after 3 months


So, the shortest possible learning period for a word is 1 month and 8 days – considering you will mark it as “easy” every time you make the quiz. This is possible for simple words you use and encounter every day. It is normal to mark more difficult words “fair”, or even “hard” a few times, before you memorize them. The process seems a bit slow to a lot of learners, but the spaced repetition guarantees that you will not only learn a certain word for day or two, but retain it permanently in your memory.