The interleaving effect is a psychological phenomenon which enables people to learn new material better when they mix together different topics as they study. Interleaving is therefore highly beneficial, and can facilitate learning in various domains, including in history, math, music, and sports.
In the following article, you will learn more about interleaving, see the various benefits that it offers, and understand why it works. Then, you will see examples of how interleaving can be used in various contexts, followed by some guidelines that will help you use interleaving as effectively as possible.
What is interleaving
Interleaving is a process where learners mix together multiple different topics as they study, in order to facilitate their learning. Interleaving, which is sometimes referred to as varied practice or mixed practice, is therefore contrasted with blocked practice (sometimes referred to as specific practice), which involves focusing on only a single topic at a time.
Examples of interleaving
There are many different ways you could use interleaving in your learning. For instance, the following are examples of how you could use interleaving when studying a certain topic on your own or in a classroom setting:
- If you’re learning vocabulary words in a new language, you could mix up the types of words that you learn during a study session. For example, instead of first learning the names of colors, and then the names of animals, and then the names of fruits, you could interleave words from each of these categories, and study them all at the same time.
- If you’re learning world history, you could mix up the history of the countries that you learn about. For example, instead of simply learning about the full history of each country at a time, you could interleave different parts of history from each country, based on a common theme, such as their actions during a specific time period.
- If you’re learning statistics, you could mix up the types of calculations that you need to perform each time you complete practice exercises. For example, instead of working on only one specific type of questions at a time, you could interleave different types of questions, in a way that means you have to actively figure out which method you should to solve the question each time.
Furthermore, interleaving can also facilitate learning outside the classroom. One example of this is the fact that interleaving can facilitate the acquisition of motor skills.
This means that, for example, that when it comes to sports, mixed practice can be used to help teach people how to throw a ball, by encouraging them to practice throws from different distances and from different directions in the same session, as opposed to throwing the ball from the same location each time. Accordingly, research has shown that interleaving can help people improve their skills in various sports, such as basketball and badminton.
Moreover, mixed practice can also be useful in other fields, such as music, where it can help people learn how to play new musical pieces.
Overall, interleaving can be implemented in nearly any type of learning. Though it’s most commonly associated with learning in a classroom setting, where its use by students is generally prompted by their teachers, interleaving can also be applied in a wide range of settings beyond this, including in self-driven learning, and in the learning of various non-academic skills.
The benefits of interleaving
Research shows that interleaving offers various benefits, such as improved retention of new information, faster acquisition of new skills, and improved mastery of existing abilities.
For example, one study showed that interleaving two tasks can help people improve their performance on both tasks more than practicing each of the tasks separately, even when they spend less time overall on each task.
Similarly, another study showed that when teaching medical students important technical skills, letting them practice by using mixed examples from different categories helps them improve their technical skills more than letter them practice using examples from the same category each time.
Interleaving also offers other benefits to people’s learning. For example, one study showed that interleaving can help students avoid the confusion that arises from learning several concepts that are highly similar at the same time.
This study focused on the fact that students often struggle to learn groups of new vocabulary words when those words have similar spelling (e.g. ‘allusion’ and ‘illusion’). Here, the study showed that mixing up such words with other, non-similar words, helps students learn the new vocabulary better, and enjoy the learning process more.
Overall, there are various benefits to implementing interleaving in the learning process. These benefits make interleaving a good study technique to use, especially since it’s a technique that is relatively simple to implement.
Why interleaving works
There are a number of cognitive mechanisms that are responsible for the benefits of interleaving, which reflects the fact that interleaving can be implemented in various forms and can benefit learners in various ways.
Contextual interference is one of the main mechanisms that is responsible for the benefits of interleaving. Essentially, this means that increased interference during the performance of a task, which occurs due to the mixing of the material, leads to the use of multiple processing strategies by learners, which in turn leads to better learning of the material.
An example of one strategy that interleaving encourages people to use is elaborative rehearsal, where learners focus on remembering the meaning of items that they are memorizing, instead of focusing on simply repeating those items verbatim.
The use of this learning strategy in conjunction with other relevant strategies not only facilitates learning by improving long-term retention of the material, but also increases people’s ability to transfer and apply concepts that they acquired in one context to other related contexts.
In addition, another reason why interleaving is beneficial is that mixed practice forces learners to figure out what strategies, techniques, and information they need to use in order to solve problems that they encounter.
For example, when it comes to learning math, giving students practice questions which only cover material from the last lesson means that students immediately know which technique or set of techniques they need to use in order to solve those questions, even before they read them.
Conversely, giving math students a mixed set of problems, which contains questions relating to various different lessons, ensures that the students have to actively figure out which techniques they need to use in order to solve those questions. This encourages them to analyze the questions in depth, and develop a better understanding of the techniques that they can use to solve them.
Furthermore, in some cases, interleaving can be beneficial because mixed practice helps learners notice the differences between items from different categories, a concept which is referred to as discriminative contrast.
Essentially, this means that when items from different groups are mixed with together, it’s easier to notice the differences between those groups. This can, for example, help teach people about the differences between different schools of philosophy or about the differences between different types of cells in the body.
Overall, there are a number of reasons why interleaving facilitates learning. Most notably, interleaving encourages in-depth processing of the material, by prompting people to use many different learning strategies due to the contextual interference that people experience when shifting between topics or tasks. Interleaving is also beneficial for other reasons, such as because it helps people notice the differences between items from different categories, when these items are mixed together.
Interleaving and spacing
It’s important to note that the effects of interleaving are distinct from those of spacing, which is the practice of increasing the gap in time between the learning of different aspects of the material. Specifically, even though spacing can facilitate learning, and even though spacing often occurs indirectly as a result of interleaving, the effects of spacing alone do not explain why interleaving is such a beneficial technique.
Furthermore, the effects of interleaving and spacing can sometimes be additive, meaning that you can improve the learning process by implementing both interleaving and spacing techniques at the same time.
However, this isn’t always the case, and there are situations where temporal spacing can interfere with the effects of interleaving. For example, in situations where interleaving helps learners by providing contrast between elements from different categories, spacing can end up interrupting the interleaving process, by making it more difficult for learners to compare the elements from the different groups.
How to use interleaving in your learning
So far, we saw what interleaving is, what are its benefits, and how it works. In the sections below, you will see several important considerations that you should take into account when implementing interleaving in your learning, so that you can implement it as effectively as possible.
Decide what criteria to use when interleaving
Since interleaving involves the mixed practice of various concepts, if you decide to use interleaving in your learning then your first consideration is what criteria to use when deciding how to mix things up.
There isn’t a single right way to do this, and which criteria you should use depends on various factors, such as the type of material that you are trying to study, your familiarity with material, and your personal preferences.
In general, however, there are three main guidelines that you should keep in mind:
- Mix things up in a way that makes sense. The criteria that you use when deciding how to mix the material should allow you to benefit from interleaving as much as possible. For example, if your goal in interleaving is to avoid seeing vocabulary words that are too similar to each other at the same time, then pick a criterion such as spelling, which allows you to avoid this issue.
- Avoid interleaving topics that are too different. If the two topics that you want to interleave are so widely different from one another, the mixed practice might end up hindering your learning, instead of facilitating it. For example, while interleaving different types of math questions might be beneficial, interleaving math questions with history lessons could end up being more confusing than helpful.
- Avoid interleaving topics that are too similar. If the two topics that you want to interleave are too similar to one another, it might feel more like blocked practice, at which point you won’t benefit from interleaving. For example, if your goal is to interleave different types of basketball throws, then simply switching between two forms of the same throw that are barely different from one another will likely not allow you to take advantage of the benefits of interleaving.
Of course, it’s difficult to conclusively determine what constitutes “too different” or “too similar” when it comes to interleaving. As such, you should generally try different options out, until you can figure out what works for you.
Decide how much you want to mix things up
Another important factor that you should take into consideration when implementing interleaving is how much you want to mix things up.
For example, let’s say that there are three topics you need to study for your exam. These topics are represented by the letter A, B, and C. Studying in the following manner constitutes blocked practice, where you focus on only one topic at a time:
Now, when it comes to deciding how to interleave these topics, there are various approaches that you could use. You can, for example, interleave them in the following manner:
However, you might also feel that this option is confusing, because there is too much variation in your practice. In that case, you might prefer to use the following pattern of mixed practice instead:
Overall, there are many different ways to interleave topics. The optimal level of interleaving is difficult to determine, since it varies in different scenarios and for different people. Sticking with the same subject too much means that you won’t benefit from interleaving, but switching topics too often could end up being more confusing than helpful.
As such, when interleaving, you should try to figure out what degree of variation works for you. Experiment and try out different solutions, until you find the one that works best given the situation that you’re in.
Remember that interleaving is hard
Using mixed practice generally makes it harder to plan your study sessions (compared to blocked practice), and makes the study process itself more taxing from a cognitive perspective, which is why the majority of people default to using blocked practice, despite the fact that it’s less effective.
This means that your performance during a practice session might be a bit worse if you use mixed practice instead of blocked practice, though you will generally remember the material better after the study session ends. This further explains why people often tend to naturally rely on blocked practice, even though interleaving is generally more beneficial in the long run.
As such, it’s important to remember is that interleaving can often be hard and frustrating, especially in the beginning, since it can take some getting used to. However, if you apply interleaving techniques properly, and stick with interleaving in the long run, it will generally improve your learning ability to a significant degree.
Remember that interleaving isn’t always the best option
For example, one study showed that when it comes to learning how to pronounce foreign vocabulary words, blocked practice benefited learners more than interleaving did. Specifically, learners benefited more from practicing the pronunciation of French words when those words were grouped together based on similarities in pronunciation, compared to when they were not.
This doesn’t mean that interleaving isn’t beneficial. Rather, it simply means that interleaving isn’t always the best option for you, and that there are scenarios where blocked practice might be preferable.
Overall, the main thing to remember is that while interleaving is often a good learning strategy to use, it might not always work. As such, when you use interleaving, try to assess how it impacts your learning, and then, based on this assessment, decide whether or not to keep using interleaving in this context in the long term.
Summary and conclusions
- Interleaving is a process where learners mix together different topics as they study, in order to facilitate their learning.
- Interleaving helps people retain new information, acquire new skills, and improve existing abilities in a wide range of domains, including in history, math, music, and sports.
- Interleaving is beneficial for several reasons, and most notably because it encourages in-depth processing of the material, by prompting people to use various learning strategies, due to the contextual interference that people experience when shifting between topics.
- When implementing interleaving in your learning, you should make sure to interleave topics at a reasonable rate, and to avoid interleaving topics that are too different or too similar to one another.
- Because different forms of interleaving will work better in different scenarios, there is no single method of interleaving that will work best for everyone, so you should experiment with different types of interleaving in order to figure out what works best for you.