The forgetting curve explains why language vocabulary does not stick - and why reminders are the solution. Hermann Ebbinghaus discovered in 1885 that memory decays exponentially without review: roughly 50% of new information is forgotten within 24 hours, 70% within a week, and up to 90% within a month. For anyone trying to learn a language, the forgetting curve is the mechanism behind vocabulary that never consolidates.

What the Forgetting Curve Is

Ebbinghaus tested his own memory by learning lists of nonsense syllables, then measuring how much he remembered at intervals. He found consistent exponential decay: the sharpest memory loss occurs in the first few hours after learning; decay continues more slowly after that; without review, most new memories are effectively gone within a month.

The curve applies to language vocabulary. A Spanish word learned today, never reviewed, will likely be forgotten by next week. This is why cramming for a vocabulary test works for the test but not for real retention - the review never happens at the right intervals.

Why Reminders Are Critical for Language Learning

The forgetting curve is predictable - which means it is beatable. A word reviewed once within 24 hours of learning decays much more slowly than an unreviewed word. A word reviewed again a few days later is more durable still. Each review at the right interval pushes the next forgetting threshold further out. After 5-6 well-spaced reviews, a word is in long-term memory.

Language learning reminders - specifically push notification vocabulary reviews - deliver those reviews at the right times. You do not have to remember to study; the app reminds you when a specific word needs review.

How Spaced Repetition Algorithms Work

Apps like Anki, TransLearn, and Lingvist implement spaced repetition: an algorithm that schedules each vocabulary item's reviews based on how well you know it. Words you recalled easily get longer review intervals; words you struggled with come back sooner. The algorithm tracks hundreds of words across your vocabulary list and presents them at near-optimal times.

Without a spaced repetition system, learners either over-review words they already know well (wasting time) or under-review words they are forgetting (losing them entirely).

Best Reminder Intervals for Language Vocabulary

Research-backed review intervals for new vocabulary:

  • First review: within 24 hours of learning
  • Second review: 2-3 days after the first
  • Third review: 1 week after the second
  • Fourth review: 2-3 weeks after the third
  • Subsequent reviews: increasing intervals (1 month, 3 months, 6 months)

This schedule is automated by spaced repetition apps. If you use push notification vocabulary review, the app handles scheduling for you.

Tools That Fight the Forgetting Curve

Anki: most customizable spaced repetition system. Free on desktop; one-time purchase on iOS. Full algorithm control.

TransLearn: push notification vocabulary delivery from your personal reading-based word list. Reviews arrive throughout the day without opening the app.

Lingvist: models the forgetting curve per-learner and schedules reviews accordingly. Example sentences with each word.

Duolingo: some spaced repetition in the curriculum, though less precise than Anki or Lingvist.

The forgetting curve is not your enemy - it is a predictable process. Language learners who use reminders and spaced repetition are directly countering memory decay. Start with free tools like Anki or TransLearn to build your first reminder schedule and stop losing vocabulary to the curve.