Principle 01 · The problem
The forgetting curve: why people forget what they learned in training
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Short answer
The forgetting curve describes how much of something we learned we forget as time goes by. Ebbinghaus measured it in the 19th century, and a 2015 replication with a single participant, as in the original, found similar results. More recent research shows that the rate of forgetting changes over time, and that a group's average curve is not any one person's curve. Reviewing at intervals, tuned to each person, is how to counter it.
What it is
The forgetting curve shows the relationship between the time since something was learned and how much of it can still be recalled. Without review, memory of new content fades, and the loss is steepest at the start.
For anyone who trains teams, the consequence is familiar: a well-run training session does not guarantee that, a few weeks later, people remember what was said.
What the research says
Forgetting does not follow a single curve
A review of the literature concluded that forgetting is not well described by a single continuous function: the rate changes from one period to the next. The authors propose phases: working memory in the first minute, early long-term memory over the next 12 hours, a transitional phase lasting about a week, and long-lasting memory after that.
Radvansky, Doolen, Pettijohn and Ritchey (2022), Journal of Experimental Psychology: Learning, Memory, and Cognition.
The average curve is not each person's curve
A mathematical analysis showed that averaging individual forgetting curves changes their shape: the average of exponential curves tends to produce a power function. A group’s curve can therefore have a different shape from each person’s curve.
Murre (2023), Journal of Mathematical Psychology.
Where the idea comes from. Hermann Ebbinghaus measured in 1880 and in 1885 how much is forgotten as a function of time. In 2015, Murre and Dros repeated the experiment with a single participant, as in the original, and intervals from 20 minutes to 31 days. They found similar results, most probably with a slight upward jump from 24 hours on.
A one-off session is not enough. Knowledge sticks when people return to it at the right moment.
How to beat the curve
- Space it out instead of cramming. Studying on two separate occasions beats studying once (Cepeda and colleagues, 2006), and a 2021 meta-analysis found a strong benefit from spacing out quiz sessions (Latimier, Peyre and Ramus). That is the principle behind spaced repetition.
- Review by answering, not rereading. Taking tests after studying leads to better performance than studying again. See retrieval practice.
- Review a little at a time. Short doses fit into the working day and can be repeated often. That is the logic of microlearning.
How the game applies it
A customer wants the Atlas Pro delivered tomorrow. What do you check first?
21- Every participant has a memory model for every question, which estimates when they are likely to forget it. There is no team average curve, because its shape may not match each person’s.
- Questions that are slipping come back first, mixed with new content.
- Each round has six questions and takes one to two minutes, so it fits into a break. See the full cycle in how it works.
References
- Murre, J. M. J. (2023). How averaging individual curves transforms their shape: mathematical analyses with application to learning and forgetting curves. Journal of Mathematical Psychology, 117, 102816. doi:10.1016/j.jmp.2023.102816
- Radvansky, G. A., Doolen, A. C., Pettijohn, K. A. & Ritchey, M. (2022). A new look at memory retention and forgetting. Journal of Experimental Psychology: Learning, Memory, and Cognition, 48(11), 1698-1723. doi:10.1037/xlm0001110
- Latimier, A., Peyre, H. & Ramus, F. (2021). A meta-analytic review of the benefit of spacing out retrieval practice episodes on retention. Educational Psychology Review, 33(3), 959-987. doi:10.1007/s10648-020-09572-8
- Murre, J. M. J. & Dros, J. (2015). Replication and analysis of Ebbinghaus' forgetting curve. PLoS ONE, 10(7), e0120644. doi:10.1371/journal.pone.0120644
- Cepeda, N. J., Pashler, H., Vul, E., Wixted, J. T. & Rohrer, D. (2006). Distributed practice in verbal recall tasks: a review and quantitative synthesis. Psychological Bulletin, 132(3), 354-380. doi:10.1037/0033-2909.132.3.354
- Ebbinghaus, H. (1885). Über das Gedächtnis: Untersuchungen zur experimentellen Psychologie. Duncker & Humblot.