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How many repetitions does it take to retain a piece of knowledge or a skill?

Early research on repetition and memory estimated that it could take as many as 17 exposures to a piece of information for an individual to retain that information. However, contemporary findings suggest that retention is more nuanced, and largely dependent on the complexity of the task or knowledge presented and the capacity of the individual receiving the information. Thus, learning and retention occur at dramatically different rates across individuals. There are no representative values that capture (in general) how quickly, how much, or for how long-lasting humans learn.

Rather than seeking the right number of repetitions for retention, the concept of “spaced reputation” has taken a prominent position in confronting the learning and forgetting phenomenon. Research shows that individuals forget what they have learned at a predictable rate, but that relearning the material at intentionally spaced intervals dramatically improves long-term recall.3 Thus, spaced repetition refers to the temporal spacing out of learning and practice for better retention of new knowledge and skill.

Research shows the benefits associated with spaced repetition include:

● Enhanced memory

● Elevated problem-solving abilities  

● Greater transfer of learning to new contexts

● Reliable and robust effects on long-term learning and retention

Spaced repetition also thwarts issues linked to overloading learners with information during intensive trainings, namely the rapid rate of forgetting (Figure 1.). Information is most likely to be forgotten the first time it is presented to an individual.6 The retention of information during first exposure is often contingent upon successive exposures at predetermined points in time. This method of distributed learning acts to refresh our memory of what was previously learned and codify the information so that the rate of exposure outperforms the rate of forgetting. The sharp decline of forgetting slowly levels out as information is recurrently reviewed and practiced.

Figure 1.

Ebbinghaus’ Forgetting Curve (Conceptual Model)

The notion of the forgetting curve was first introduced by German Psychologist, Hermann Ebbinghaus. Ebbinghaus’s research posited three major ideas:

● The greater the amount of material to be learned, the longer it will take to learn it.

● Learning is more effective when spaced out over time, rather than carried out in one session.

● The rate of forgetting is at its highest when something is first learned and slows down over time.


Ebbinghaus’s study was replicated and analyzed in 2015, with resulting evidence fully backing his original findings. With an appreciation for the value of spacing out learning and practice, to improve retention, this pedagogy appears to play a key role in the retention of skill and knowledge.

Accompanying the utility of spaced repetition in the learning process is the importance of experiential learning. A profound conceptual development regarding the importance of experiential learning was born out of the Center for Creative Leadership, with McCall, Lombardo, and Morrison’s 70:20:10 model.

This model maintains that hands-on experience (the 70%, of the 70:20:10 model) is the most beneficial to learners’ retention because it enables them to discover and refine job-related skills, make decisions, and address challenges.

Experienced-based training also allows learners to learn from their mistakes and receive immediate feedback on their performance. The 20% of this model refers to learning that comes from developmental relationships with other people. While, the 10% refers to learning that comes from formal training and coursework.

VR to Aid Retention

Research findings on spaced repetition demonstrate, that as a teaching method, it can effectively counter how quickly information from intensive (often expensive) training is forgotten. Additionally, adhering to the 70:20:10 model highlights the overwhelming benefits of experiential-learning on a learner’s retention.

Here, the opportunity for virtual reality (VR) simulation is evident to supplement initial information exposure and aid in long-term retention through experiential based, interval training.

Implementing VR simulation into training and development programming provides trainees greater access and frequency to practice. Yet, perhaps more critical to training success is that VR simulations generate interactive, life-like conditions not possible to replicate in most other training platforms.

VR and ROI

Moving from eLearning or live trainings to a VR platform carries significant financial implications. The equipment for VR training often consists of a VR headset and supporting technology (generally a $1,000 - $2,500 investment). With this equipment, visceral training exercises and scenarios can be seamlessly developed and implemented with immediacy. Leading research groups estimate that the cost of developing VR simulations is considerably less expensive than creating and carrying out most e-learning or live trainings.

Financial savings are found both in this initial investment and on the back end by reducing the use (and possible jeopardization) of expensive equipment, the number of trainers, and the need for training supplies. Further, VR allows trainees to be immersed in a psychologically realistic environment, without the possibility of physical harm. Eliminating threats to physical health.

Innovations in VR technology afford users a unique and advantageous opportunity to train and learn like never before. Organizations that choose to harness this technology are positioned to be pioneers, change agents, and top performers in modern business.


[1] Ausubel, D. P., & Youssef, M. (1965). The effect of spaced repetition on meaningful retention. Journal of

General Psychology, 73, 147–50.

[2] Thalheimer, W. (2010, April). How much do people forget? Retrieved from: http://www.work-


[3] Custers E.J., & Ten Cate, O.T. (2011). Very long-term retention of basic science knowledge in doctors after

graduation. Medical Education 45(4), 422-430. https://doi.org/10.1111/j.1365-2923.2010.03889.x.

[4] Kang, S. H. (2016). Spaced repetition promotes efficient and effective learning: Policy implications for

instruction. Policy Insights from the Behavioral and Brain Sciences, 3(1), 12-19. https://doi.org/10.1177/2372732215624708

[5] Cull, W. L. (2000). Untangling the benefits of multiple study opportunities and repeated testing for cued recall.

Applied Cognitive Psychology, 14, 215–235.

[6] Ebbinghaus, H. (1880). Original manuscript “On memory.” Passau: Passavia University Publishing.

[7] Murre, J.M.J., & Dros, J. (2015). Replication and analysis of Ebbinghaus’ forgetting curve. PLoS ONE 10(7):

e0120644. https://doi.org/10.1371/journal.pone.0120644

[8] McCall, M. W., Lombardo, M. M., & Morrison, A. M. (1988). Lessons of experience: How successful executives

develop on the job. Simon and Schuster.

[9] Wentworth, D. (2018, January 25). The impact and potential of virtual reality training in high-consequence

industries. Training: The source for professional development. Retrieved from: https://trainingmag.com/impact-and-potential-virtual-reality-training-high-consequence-industries/

Posted on
April 29, 2019
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