What is the spacing effect?
The spacing effect is the finding that the same amount of study produces longer-lasting memory when it is spread out over time (distributed practice) than when it is crammed together (massed practice). Ebbinghaus noticed it in the 1880s, and hundreds of studies have confirmed it since.
- Also called
- Distributed practice, spaced practice
- Opposite
- Massed practice, cramming
- Evidence
- Hundreds of studies, including Cepeda et al. (2006)
- Effect
- Especially large for long-term retention
Spacing vs. cramming
| Aspect | Cramming (massed) | Spaced practice |
|---|---|---|
| Schedule | 4 hours the night before | 1 hour a day for 4 days |
| Test right away | Similar, may even seem better | Similar |
| Test a week later | Much forgotten | Far more retained |
| How it feels | Smooth and easy | A bit more effortful |
Cramming seems to work because the test is the very next day. When Cepeda and colleagues (2006) synthesized more than 300 experiments, spaced study consistently produced better performance on delayed tests than the same amount of massed study.
Why does spacing work?
- Retrieving something you’ve partly forgotten strengthens it more. Spacing slots reviews into the forgetting curve.
- Different study contexts link the memory to more cues.
- Cramming creates a false sense of fluency; spacing reduces that illusion of knowing.
What is the optimal gap?
Cepeda and colleagues (2008) tested more than 1,350 people and found that the longer you need to remember something, the longer the gap between reviews should be. But the ratio shrinks as the interval grows: the best gap was about 15% of a one-week retention interval but only about 5% of a one-year interval.
| Time until test | Suggested first review gap (approx.) |
|---|---|
| 1 week | About 1 day |
| About 5 weeks | About 11 days |
| About 10 weeks | About 3 weeks |
| About 1 year | About 3 weeks |
Building a spaced study plan
- Start three weeks before midterms. Rotate subjects with gaps of two to three days.
- Mix subjects in a day. Interleaving beats blocking one subject.
- Make reviews active. Spacing is strongest combined with retrieval practice.
- Use spaced-repetition apps. Flashcard apps show missed cards often and known cards rarely.
In Dunlosky and colleagues’ (2013) review of ten study techniques, distributed practice and practice testing were the only two rated high utility.
Frequently asked questions
- What is the spacing effect?
- The finding that spreading study over time leads to longer-lasting memory than cramming the same amount into one session.
- Does cramming work at all?
- It can help for a test the next day, but within days you forget far more than with spaced study.
- How far apart should I space reviews?
- The longer you need to remember, the longer the gaps; in experiments, about a day worked best for a test a week away and about 11 days for one five weeks away.
References
- 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.
- Cepeda, N. J., Vul, E., Rohrer, D., Wixted, J. T., & Pashler, H. (2008). Spacing effects in learning: A temporal ridgeline of optimal retention. Psychological Science, 19(11), 1095–1102.
- Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J., & Willingham, D. T. (2013). Improving students’ learning with effective learning techniques. Psychological Science in the Public Interest, 14(1), 4–58.