The forgetting curve describes how memory for newly learned information declines over time when it is not reviewed. Forgetting is typically steep at first and then levels off, so most loss happens soon after learning.
How it works
When you first learn something, the memory is fragile. Without review, your ability to recall it drops quickly over the following hours and days, then more slowly. How quickly depends on how well you learned it in the first place, how meaningful it is, how it connects to what you already know, and whether you sleep and review.
The important part for students is what happens with review. Each time you successfully recall the information, the memory becomes more stable and fades more slowly, so the next review can come later. This is the principle behind spaced repetition. It also explains why cramming can get you through a test the next morning but leaves little a few weeks later.
How to use the forgetting curve (steps)
- Review soon after learning. Test yourself on a lecture the same day or the next day, while most of it is still retrievable.
- Use recall, not rereading. Active recall strengthens memory more than reading it again.
- Expand the gaps. Review again after a few days, then a week, then a few weeks.
- Shorten gaps for hard material. If you forget something, bring it back sooner.
- Let software schedule it. A spaced repetition app or the Leitner system handles timing for you.
- Start early. The more spaced reviews you can fit before an exam, the flatter the curve by exam day.
Evidence
Hermann Ebbinghaus published Über das Gedächtnis (Memory) in 1885. Using himself as the only subject, he memorised lists of nonsense syllables and measured how much effort it took to relearn them after different delays, producing the first forgetting curve. He also found that spreading out repetitions improved retention. Murre and Dros (2015) replicated his experiment in PLOS ONE and found a very similar curve. Later research on the spacing effect, including Cepeda and colleagues’ 2006 meta-analysis, and on the testing effect, including Roediger and Karpicke (2006), showed how spaced, effortful review slows forgetting.
Beating the forgetting curve with Duetoday
Duetoday turns each lecture, PDF or YouTube video into flashcards right after you upload it, so you can start reviewing while the material is fresh. Built-in spaced repetition schedules each card for review before you are likely to forget it, and practice tests let you check whole topics before an exam.
