What is spaced repetition?

Spaced repetition is a technique where individuals review lessons at increasing intervals to memorize information. Spaced repetition is based on the premise that the brain learns more effectively when the individual “spaces out” the learning process. Thus, it can be used as a mnemonic technique to transform short-term memory into long-term memory.

Aspect	Explanation
Definition	Spaced Repetition is a cognitive learning technique that leverages the psychological spacing effect to enhance long-term memory retention. It involves reviewing and revisiting learned information at increasing intervals over time, with each review designed to occur just before you are likely to forget the material. This approach optimizes the consolidation of knowledge in your memory by strengthening neural connections through repeated exposure. The key principle behind spaced repetition is that regular, well-timed reviews of material lead to more efficient and lasting retention compared to cramming or massed practice. It is widely used in education, language learning, and various forms of skill acquisition to improve the effectiveness of learning and memory retention.
Key Concepts	– Spacing Effect: The spacing effect refers to the phenomenon where information is better remembered and retained when it is reviewed at intervals over time rather than in a single, intensive study session. – Optimal Timing: Spaced repetition algorithms determine the ideal timing for reviewing material based on the learner’s previous performance and memory decay rates. – Active Recall: The technique often involves actively recalling information from memory, which enhances retention. – Incremental Intervals: Spacing intervals are incrementally increased with successful recall, reinforcing memory over time. – Adaptive Learning: Spaced repetition systems (SRS) adapt to individual learning progress, focusing on material that needs review.
Characteristics	– Regular Review: Spaced repetition requires consistent and scheduled review sessions. – Adaptive Algorithms: Spaced repetition systems adapt the timing of reviews based on individual performance. – Active Engagement: Learners are actively engaged in recalling information during review sessions. – Incremental Learning: Review intervals increase progressively as learners demonstrate retention. – Efficient Retention: The technique optimizes memory retention by minimizing forgetting.
Implications	– Long-Term Retention: Spaced repetition enhances the long-term retention of learned material. – Efficient Learning: It promotes efficient learning by focusing on material that is more likely to be forgotten. – Minimized Forgetting: Regular review sessions minimize the impact of the forgetting curve. – Optimized Study Time: Learners can maximize the effectiveness of their study time by using spaced repetition. – Adaptive Learning: Spaced repetition adapts to individual learning pace and memory strengths and weaknesses.
Advantages	– Effective Retention: Spaced repetition is highly effective in retaining knowledge over extended periods. – Time Efficiency: It makes the most efficient use of study time by targeting areas of weakness. – Active Learning: Active recall during reviews reinforces memory and learning. – Adaptive and Personalized: Spaced repetition systems tailor review schedules to individual learning needs. – Enhanced Learning: The technique promotes deep and lasting understanding of material.
Drawbacks	– Complexity: Some learners may find the implementation of spaced repetition systems challenging. – Initial Setup: Setting up spaced repetition schedules can be time-consuming. – Overlearning: Overemphasizing spaced repetition can lead to excessive review, potentially wasting time. – Subjective Experience: Not all learners may enjoy or benefit from the structured nature of spaced repetition. – Incompatible with All Content: Some types of learning may not align well with spaced repetition techniques.
Applications	– Language Learning: Spaced repetition is widely used in language learning apps and courses to help learners memorize vocabulary and grammar rules. – Medical Education: Medical students and professionals use spaced repetition to retain vast amounts of medical knowledge. – Academic Learning: Students apply spaced repetition to improve retention in subjects like science, history, and mathematics. – Professional Development: Professionals use spaced repetition for certification exams and skill development. – Self-Study: Self-learners and autodidacts utilize spaced repetition to master various topics and skills.
Use Cases	– Anki: Anki is a popular spaced repetition software that allows users to create and review digital flashcards. – Duolingo: The language learning app Duolingo incorporates spaced repetition to help users memorize vocabulary and sentence structures. – Medical Boards: Medical students preparing for board exams often rely on spaced repetition to memorize complex medical concepts. – Academic Success: Students use spaced repetition to excel in subjects that require memorization, such as history or biology. – Self-Paced Learning: Self-learners employ spaced repetition to independently acquire knowledge and skills.

Table of Contents

Understanding spaced repetition

To understand the idea of spaced repetition, first imagine that you’re a fitness fanatic who wants stronger arms.

To achieve this, you would not walk into the gym and start with 100-pound dumbbells.

You may instead start with the 10-pound dumbbells and allow your body to rest and adjust before moving to something heavier.

In other words, you would repeat the process and move up to 20, 30, 40, and finally 100-pound dumbbells.

Spaced repetition works in much the same way, except this time, replace stronger arms with increased knowledge and dumbbells with lesson-based information.

This method of learning trains the brain to store information in long-term memory for a longer period of time.

Spaced repetition is based on the premise that the brain learns more effectively when the individual “spaces out” the learning process.

Note that the lessons themselves do not need to be identical. What’s important is that a sufficient amount of time passes between each.

When this condition is respected, spaced repetition is far more effective at improving long-term memory than other methods such as rote learning or last-minute cramming.

It also increases the likelihood that the individual not only acquires information but can use it in other contexts.

What is the optimal time between lessons?

The subject of optimal spacing in spaced repetition is somewhat contentious.

In 2014, Polish researcher Dr. Piotr Wozniak developed SuperMemo, the first software-based learning system using algorithms to determine optimal intervals:

First repetition (lesson) – 1 day.
Second repetition – 7 days.
Third repetition – 16 days.
Fourth repetition – 35 days.

While there are now many other spaced repetition apps that use increasingly sophisticated algorithms, the intervals they suggest are guides at best.

This is because brain and memory science are rather nuanced and it can be difficult to make specific recommendations that will suit everyone.

Having said that, the interval can be increased or decreased depending on how easily pieces of information are recalled or learned.

Spaced repetition and Ebbinghaus’s forgetting curve

The Ebbinghaus forgetting curve is a graphical representation of how information is forgotten with time.

The curve is exponential such that it starts with near-perfect recall on Day 0 before a precipitous drop in retention over the next few days.

After a week or two, the individual will remember very little of the information.

Spaced repetition can be used to recall information at certain times over this period and ensure the forgetting curve never approaches zero.

In other words, spaced repetition forces the learner to review the information stored in their brain before everything is lost.

As we touched on earlier, our memory becomes stronger when we revisit information after some of it is forgotten.

This idea is explained by the theory of disuse, which posits that well-learned information may be difficult to retrieve from our memory if there is interference from other information or contexts.

To increase our ability to retrieve the right information and make it more accessible, we must be able to recall that piece of information repeatedly.

Case Studies

Sales Training and Product Knowledge:
- Industry: Retail, Consumer Goods
- Description: Companies can utilize spaced repetition techniques to enhance sales training programs and improve product knowledge among sales representatives. Instead of conducting one-time training sessions, organizations can implement spaced repetition systems to reinforce key product features, benefits, and selling points over time. By delivering bite-sized product updates, quizzes, and scenario-based simulations at regular intervals, sales teams can maintain a deep understanding of the product portfolio and effectively communicate value propositions to customers.
- Example: A multinational electronics manufacturer implements a spaced repetition training program for its sales force to ensure consistent product knowledge across different regions. Sales representatives receive weekly email newsletters containing product updates, success stories, and quiz questions. Additionally, the company provides access to an online learning platform where sales reps can review interactive modules and participate in virtual role-playing exercises to practice product demonstrations and objection handling.
Compliance Training and Regulatory Updates:
- Industry: Banking, Finance, Healthcare
- Description: Organizations subject to regulatory compliance requirements can leverage spaced repetition techniques to reinforce compliance training and stay abreast of regulatory updates. Instead of conducting annual compliance refreshers, companies can implement spaced repetition systems to deliver targeted compliance modules and assessments at regular intervals. By providing employees with timely reminders and quizzes on key regulatory policies and procedures, organizations ensure ongoing adherence to compliance standards and mitigate regulatory risks.
- Example: A global financial institution adopts a spaced repetition approach to compliance training for its employees operating in highly regulated markets. The company utilizes a learning management system (LMS) with built-in spaced repetition algorithms to deliver compliance modules and track employee progress. Compliance topics such as anti-money laundering (AML) regulations and data protection laws are reinforced through monthly quizzes and microlearning activities, ensuring that employees retain essential knowledge and comply with regulatory requirements.
Customer Service Excellence and Soft Skills Development:
- Industry: Hospitality, Service Industries
- Description: Businesses focused on delivering exceptional customer service can employ spaced repetition techniques to reinforce soft skills development and enhance service excellence among frontline employees. Instead of conducting one-off training workshops, companies can implement spaced repetition systems to deliver ongoing coaching, feedback, and skill reinforcement activities. By providing employees with regular opportunities to practice communication techniques, problem-solving strategies, and conflict resolution skills, organizations can improve customer satisfaction and loyalty.
- Example: A luxury hotel chain integrates spaced repetition into its customer service training program for front desk staff, concierge teams, and guest relations personnel. The hotel conducts monthly workshops focused on key service principles such as empathy, active listening, and personalized guest experiences. In addition to face-to-face training sessions, employees receive weekly email prompts with scenario-based challenges and reflective exercises to reinforce learning and encourage continuous improvement in customer interactions.
Language Learning and Cross-Cultural Training:
- Industry: International Business, Education
- Description: Companies operating in global markets can leverage spaced repetition techniques to facilitate language learning and cross-cultural training for employees. Instead of relying solely on traditional language courses or cultural sensitivity workshops, organizations can implement spaced repetition systems to support ongoing language acquisition and cultural competence development. By providing employees with access to language learning apps, virtual language tutors, and interactive cultural immersion experiences, businesses can equip their workforce with the linguistic and intercultural skills needed to succeed in diverse environments.
- Example: A multinational corporation with offices worldwide implements a spaced repetition language learning program to enhance employees’ proficiency in foreign languages and foster cross-cultural collaboration. The company partners with a language learning platform that offers personalized language courses tailored to employees’ proficiency levels and learning goals. Through regular practice sessions, vocabulary drills, and cultural awareness modules, employees improve their language skills and gain insights into cultural nuances, facilitating effective communication and teamwork across borders.

Key takeaways:

Spaced repetition is a technique where individuals review lessons at increasing intervals to memorize information.
Spaced repetition is based on the premise that the brain learns more effectively when the individual “spaces out” the learning process. Whilst there is some debate around how much time should pass between lessons, a software-based learning system found that learning on the 1^st, 7^th, 16^th, and 35^th days was optimal.
Spaced repetition can be used in conjunction with Ebbinghaus’s forgetting curve to recall information and ensure the learning curve never approaches the bottom of the graph.

Key Highlights

Spaced Repetition Technique: Spaced repetition is a learning technique where individuals review lessons or information at increasing intervals to effectively memorize it. This technique capitalizes on the brain’s tendency to retain information better when learning is spaced out over time.
Long-Term Memory: The goal of spaced repetition is to transform short-term memory into long-term memory. By spacing out review sessions, the brain is trained to retain information for a more extended period.
Analogous to Fitness Training: The concept of spaced repetition can be compared to fitness training. Just as one would start with lighter weights and gradually increase the load, learning starts with basic information and is reinforced over time with increasing intervals.
Effectiveness over Rote Learning: Spaced repetition is shown to be more effective for improving long-term memory compared to methods like rote learning or last-minute cramming. It enhances the likelihood of not only acquiring information but also applying it in various contexts.
Optimal Timing: While the exact timing between review sessions can vary, an example from SuperMemo suggests intervals of 1 day, 7 days, 16 days, and 35 days for successive repetitions. These intervals optimize memory retention. However, the specific intervals might need adjustments based on individual recall ability.
Ebbinghaus’s Forgetting Curve: The Ebbinghaus forgetting curve illustrates how information is forgotten over time, with a steep drop shortly after learning. Spaced repetition can counteract this curve by revisiting information at specific intervals, preventing memory decay and loss.
Theory of Disuse: Spaced repetition aligns with the theory of disuse, which explains that well-learned information can become difficult to retrieve from memory if not revisited. Regular recall reinforces memory accessibility and retrieval.