Combatting the Forgetting Curve

by | Nov 30, 2020 | Instructional Design

You’ve probably heard the adage that we have memories like a goldfish. Of course, this has been debunked, but the myth persists.

I wonder if part of the persistence of the myth is grounded in the forgetting curve. In 1885 Hermann Ebbinghaus studied memory and found that it diminishes over time without spaced repetition. His graph was dubbed the forgetting curve.

Source: Chun, Bo Ae & hae ja, Heo.

The concept has been highly researched since his discovery. A more recent study1 found that within:

  • 1 hour the average person forgets 50% of new information.
  • 24 hours the average person forgets 70% of new information.
  • 1 week the average person forgets 90% of new information.

How can instructional design minimize the effects of the forgetting curve?

As instructional designers, we can design learning to reduce the effects of the forgetting curve and increase the opportunity for participants to transfer what they learn to their jobs.

Rehearsing – Revisit content after it’s been learned

Research2 has shown that ‘rehearsing’ has a direct impact on how well individuals can retrieve information from long-term memory. Quizzes with fill in the blank or multiple choice questions are an excellent way of rehearsing. They are better than re-reading because they require the individual to recall the information. Spaced rehearsal increases student performance by 14%.3

“Booster episodes do not need to re-teach the material. The information has been learned once, and the learner does not need to encode the information a second time. Instead, spaced recall is used merely to provide a retrieval opportunity that signals to the brain that the information is essential and should be retained.”

Fortino, Andres and Lowrance, Roy. Page 240.

Spacing the rehearsing

Distributed practice is also known as spaced repetition or spaced practice. It combines initial learning with ‘booster episodes.” The positive effects are well documented in the literature. However, studies have focused on lag times of seconds or minutes between learning and revisiting instead of days, weeks or months. These short lag times are less applicable to a corporate training context. A study by Cepeda, Coburn, Rohrer et al. (2009)4 examined the impact of gaps on learning recall. They conducted two experiments that examined gaps (period of time between learning content and rehearsals) and test scores (assessment of what students remembered).

  • Experiment 1 had gaps between 5 minutes to 14 days and a 10-day test delay.
  • Experiment 2 had gaps between 20 minutes to 168 days and a 6-month test delay.

The researchers found that varying the gap between learning and revisiting content had a large effect. Recall improved by 34% as the gap increased from zero to one day. After one day, there was a small but steady decline in test scores. See the chart below.

As learning and development professionals, we should space learning and revisiting content by one day to improve retention. I do this with a mutual fund company I work with. Participants learn a concept, and a day later, the Learning Management System (LMS) sends an automatic email with a reminder or question about the content.  

If having a day-long gap between learning and a booster episode supported learning, what about gaps that are even longer? And how long is too long? The researchers studied this too. The second experiment had startling results. It showed that a 28-day gap resulted in a 151% improvement over a 0-day gap.

But how long is too long? The second experiment showed that increasing the gap from 28 to 168 days produced a relatively modest decline in retention of only 23%. So 28 days seems to be the best, but extending the gap time is okay too.

The authors suggest the penalty for too short a gap is far greater than the penalty for too long a gap.

Instructional design tips

As we design training programs, we can include design elements to lessen the impact of the forgetting curve and help participants apply what they learn to their job.  

  • Include rehearsal opportunities so learners can revisit information they learned earlier and ‘build remembering muscles.’
  • Use quizzes instead of re-presenting content, so learners retrieve already-learned information.
  • Reduce quiz stress by emphasizing recall instead of assessment.
  • Create either fill in the blank or multiple-choice questions.
  • Space learning and “booster episodes” in days and months instead of hours or weeks.

Curious to learn more?

Here is some additional information about how I’ve helped clients with learning design.

When you’re ready, here are a few ways I can help you and the employees in your organization:

  • Redesign for Online: Process, templates and support
    Five-module program for L&D Professionals to redesign an existing program for online delivery. The design and delivery includes adult learning principles! If you need help redesigning your program, click here for more information.
  • Designing learning curriculum that incorporates different delivery channels – online, in-person as well as non-learning approaches such as coaching.
  • Designing training courses (in-person and online) that focus on changing performance and aligning with your business needs.

Check out the other services I provide to clients to help them improve employee performance.


Chun, Bo Ae & hae ja, Heo. (2018). The effect of flipped learning on academic performance as an innovative method for overcoming ebbinghaus’ forgetting curve. 56-60. 10.1145/3178158.3178206.

1 – Karpicke, J. D., 2012. Retrieval-based learning: Active retrieval promotes meaningful learning. Current Directions in Psychological Science, 21(3), 157-163.

2 – Fundus (1970) as cited in Fortino, Andres and Lowrance, Roy. “Practice makes perfect: Memory retrieval strategies to improve student academic performance.” Academy of Management Annual Meeting Proceedings. 2019. Vol. 2019 Issue 1, p239-244.

3 – Fortino, Andres and Lowrance, Roy. “Practice makes perfect: Memory retrieval strategies to improve student academic performance.” Academy of Management Annual Meeting Proceedings. 2019. Vol. 2019 Issue 1, p239-244. Page 240.

4 – Cepeda, Nicholas J., Coburn, Noriko, Rohrer, Doug, et al. “Optimizing Distributed Practice: Theoretical Analysis and Practical Implications.” Experimental Psychology, 56(4) 2009.