Spaced Retrieval, Retrieval Practice, and Knowledge Guru: What Research Tells Us

Knowledge Guru’s game engine is designed to tap into two powerful and empirically supported instructional strategies—Retrieval Practice and Spaced Retrieval.

Retrieval Practice requires learners to recall information rather than simply re-read or re-listen to it. A review of the pertinent scientific literature reveals that the benefits of retrieval practice have been known for at least 100 years and they have been demonstrated with many diverse groups [1]. Retrieval Practice alone can provide improved recall performance by as much as 10-20%. [2] When combined with Spaced Retrieval the effect is multiplied. In fact, “the act of retrieving information from memory actually alters the retrieved memory by elaborating on the existing memory trace and/or creating additional retrieval routes. One consequence of these changes is that the probability of successful retrieval in the future is increased, making testing a potent mechanism for enhancing long term retention.”[3]

Spaced Repetition

Spaced Retrieval involves providing students with quiz or course content spaced over time and it, too, is among the most robust findings in educational psychology research. [4] It turns out that the greater the amount of spacing between retrieval events, the greater the potential benefit to retention. Spaced Retrieval helps learners retain access to memorized information over long periods of time because the spacing promotes deeper processing of the learned material. Ideally, the time between the learning events is greater than 24 hours, but shorter times have also been found to be effective. As long as 8 years after an original training, learners whose practices were spaced showed better retention than those who practiced in a more concentrated time period. [5]

Spaced Retrieval avoids two inherent problems with mass practice (learning all the information at once); the problems of learner fatigue and the likelihood of interference with preceding and succeeding learning.

One study combining Spaced Retrieval and Retrieval Practice indicated retention benefits of between 35-60% for students in the subject matter of Anatomy and Physiology over the control group. [6]

Additionally, using the combination of a quizzing game and online lectures, student’s minds will focus more on the course and wander less, which is always an issue in online learning. Researchers have found that by interspersing online lectures with short tests, student mind-wandering decreased by half, note-taking tripled, and overall retention of the material improved. As the researchers indicated, “In our experiments, when we asked students if they were mind-wandering, they said yes roughly 40 percent of the time. It’s a significant problem.” But using online quizzing in a manner such as Knowledge Guru will reduce mind wandering and increase performance.

In the study by Harvard researchers, participants were asked to learn from a 21-minute video lecture on statistics. The participants were told that the lecture would be divided in four parts, separated by a break. The students were all told that they might be quizzed at any time (when, in fact, only one condition had quizzing the first three times and all conditions had the quiz the fourth time.) [7]

During the break the participants were asked to perform math problems for a minute, and then would be assigned to one of three groups:

  • Perform more math problems for two more minutes (“untested group”)
  • Answer quiz questions for two minutes on the material they had just learned (“tested group”)
  • Review by seeing questions with the answers provided (“restudy group.”)


The result was that the students who were tested took more notes during the lecture and reported that their minds wandered less (19% as compared to 40%.)  In addition, the students who were tested on all segments out performed both of the other groups (tested = 90%, restudy = 76%, nontested = 68). Another finding was that students who were tested after each segment indicated that they were less anxious about the fourth test than students from the other two groups.

The researchers believe that the results are because the testing at the end of each segment, act as an incentive for students to pay closer attention to the lecture because they know they’ll have to answer questions at the end of each segment.

The researchers concluded: The present results… highlight the specific cognitive mechanism by which testing can facilitate learning. In particular, testing can be used to help students sustain attention to lecture content in a manner that discourages task-irrelevant (mind wandering) and encourages task-relevant (note taking) activities, and hence improves learning. Importantly, the benefits of testing for learning were accompanied by reductions in test anxiety (possibly because students became accustomed to testing style or as a result of positive feedback from earlier tests) and subjective estimates of cognitive demand.

References cited

[1] Larsen DP, Butler AC, Roediger HL 3rd. Repeated testing improves long-term retention relative to repeated study: a randomized  controlled trial. Med Educ  43: 1174–1181, 2009.

[2] Dobson, J. L. (2013) Retrieval practice is an efficient method of enhancing the retention of anatomy and physiology information Advances in Physiology Education 37: 184–191, 2013; doi:10.1152/advan.00174.2012.

[3] Roediger, H. L., & Butler, A.C . (2013). Retrieval practice (testing) effect. In H. L. Pashler (Ed.),Encyclopedia of the mind. Los Angeles, CA: Sage Publishing Co.

[4] Carpenter SK, DeLosh EL. (2005) Application of the testing and spacing effects to name learning. Applied Cognitive Psychology 19: 619–636, 2005. And Cull W. (2000) Untangling the benefits of multiple study opportunities and repeated testing for cued recall. Applied Cognitive Psychology 14: 215–235, 2000. And Cull W, Shaughnessy JJ, Zechmeister EB.(1996) Expanding understanding of the expanding-pattern-of-retrieval mnemonic:toward confidence in applicability. Journal of Experimental Psychology Applied 2: 365–378.

[5] Kapp, K. M. (2012) The Gamification of Learning and Instruction: Game-based Methods and Strategies for Training and Education. New York: Pfeiffer.

[6] Dobson, J. L. (2013) Retrieval practice is an efficient method of enhancing the retention of anatomy and physiology information Advances in Physiology Education 37: 184–191, 2013; doi:10.1152/advan.00174.2012.

[7] Szpunar, K. K., Khan, N. &, & Schacter, D. L. (2013). Interpolated memory tests reduce mind wandering and improve learning of online lectures. Proceedings of the National Academy of Sciences, published online April 1, 2013 doi:10.1073/pnas.122176411


The Corporate Learning Guide to Spaced Repetition and Feedback Loops (Free Download)

There are many causes for ineffective training, but one of L&D’s greatest enemies is forgetting. If learners fail to embed new knowledge into their long-term memory, they will be unable to apply it on the job. When training is treated as a one-time event, tangible results will be limited.

You know there’s a problem. But what can you do about it?

We’ve put together a free guide highlighting the research-based approaches of spaced repetition and immediate feedback. Research has repeatedly shown that using these techniques can increase retention of new knowledge and skills. By basing your own learning designs off of these principles or using a solution that already has the learning principles built in, you can greatly increase what your learners will remember.

What’s in a name?

Spaced repetition goes by several names in the L&D world. You might have heard this technique referred to as spaced learning and repetition, interval reinforcement, distributed practice, the spacing effect, or something else entirely. We have chosen to use the term “spaced repetition” for the purpose of this guide.

Who’s this guide for?

Any business professional looking for one of the following outcomes through a corporate learning program:

  • Less accidents
  • More sales
  • Better customer service
  • Faster new hire on-boarding
  • Fewer mistakes

What’s in the guide:

  • The five corporate learning content areas (accounting for 55% of total training) that benefit the most from spaced repetition approaches.
  • Five common learning solutions that fail to help learners retain knowledge.
  • The real story behind the forgetting curve, and what the latest research has to say about Herman Ebbinghaus’ theory.
  • An introduction to spaced repetition, including “micro spacings” and “macro spacings.”
  • The difference between feedback that helps learners remember and feedback that doesn’t.
  • A case study of an organization that used a spaced repetition solution and achieved tangible business results.


The Learning Design Behind Knowledge Guru Games

Interested in spaced learning and distributed practice? Then download our free Primer on Spaced Repetition and Feedback Loops. This guide will teach you everything you need to know about these concepts so you can incorporate them in your own training.

Many of our customers are first drawn to Knowledge Guru because they are looking for a serious game. They want their training to be more game-like and fun for learners. But as much as we are believers in the power of games to improve learning outcomes, the fact that Knowledge Guru is a game is not as important to the learning value as the learning principles we built into the game’s design.

Any game becomes useless for learning unless learning is carefully built into the game mechanics and game elements. In the case of Knowledge Guru, we use three research-based learning principles within the game to help players acquire knowledge. These principles are at work in every Knowledge Guru game, no matter what content you put into the tool (as long as you write your question sets correctly!).

Here’s a brief overview:



It’s intuitive, really. We need to repeatedly study material in order to remember it. In Knowledge Guru, game questions are grouped into question sets, which are groups of three questions. Each question set is linked to a learning objective in the game. Each question set teaches one piece of information, but the three questions each approach it in a different way. Question A might be fact recall, Question B a true or false question, and Question C a scenario question where learners apply the information in context. More about creating question sets here.

Another way to think of repetition is practice testing. A 2013 report by the Association for Psychological Science rated Practice Testing as a “highly effective learning tactic.” Giving learners more evaluations aids in further learning… and each path in the Knowledge Guru game is another mini “evaluation” or challenge learners must complete. Because the information is brought to mind multiple times, it is easier to remember. This is similar to the learning benefit found from using flash cards.

Spaced learning


Sometimes referred to as distributed practice, spaced learning happens when we space our learning out into small chunks over time. The same Association for Psychological Science report referenced above found that intentionally breaking learning into smaller bits and spacing the practice out builds long-term memory better than other study methods.

We use spaced learning in a “macro” and “micro” way within Knowledge Guru. The most obvious is the Guru Grab Bag mode, which contains all of the questions from the normal game mode, but is only unlocked when learners complete the regular game. By returning to the game days or weeks after completing it, the learning is reinforced.

Spaced learning can even be beneficial if the repetitions are spaced only a few minutes apart. Since the three questions in a set are placed on paths A, B, and C, learners are exposed to the same information after short breaks (if they complete the topic in one sitting).

Immediate Feedback


When learners get a question right in Knowledge Guru, three things happen:

  1. They move on to the next question.
  2. Points are awarded.
  3. Depending on where they are in the game, achievements are earned.

In this way, the game is providing feedback to players for the performance. It’s saying “Good job! You’re getting it!” When players get a question wrong, they receive immediate feedback explaining their misstep, and the following things happen:

  1. Points are deducted.
  2. The game provides an explanation of the mistake.
  3. The learner returns to the same question and must try again.

Instead of merely letting players get the answer wrong, the game immediately corrects them and helps them learn why they answered incorrectly. This is how Knowledge Guru helps people learn content, rather than simply evaluating them on how much they already know.

It’s More Than Just a Game

While gaming is central to Knowledge Guru, we see the learning principles behind the game as the most valuable element of the product. We’ve aligned our efforts so each enhancement and iteration uses the principles of spaced learning, repetition, and immediate feedback to help people acquire knowledge faster.