Cognitive Load Theory CLT

Cognitive Load Theory

Cognitive Load Theory (or CLT) is a theory which aims to understand how the cognitive load produced by learning tasks can impede students’ ability to process new information and to create long-term memories.

Cognitive load is typically increased when unnecessary demands are imposed on a learner, making the task of processing information overly complex. Such demands include the unnecessary distractions of a classroom and inadequate methods used by teachers to educate students about a subject. When cognitive load is managed well, students are able to learn new skills easier than when high cognitive load interferes with the creation of new memories.

By understanding the principles behind cognitive load theory, teachers can optimize the way they present novel ideas to students to make them easier for their audience to understand.

Cognitive load theory was first outlined in 1988 by John Sweller, an educational psychologist at the University of New South Wales, Australia. Sweller built on the working memory model of memory which proposed that long-term memories develop when auditory and visual information is processed (or rehearsed) to a greater degree than other everyday observations (Baddeley and Hitch, 1974). Sweller believed that factors which make learning unnecessarily complex, or distract us from information we are trying to pay attention to, increase a person’s cognitive load as they are processing it. As a result of higher cognitive load, a stimulus is more difficult to pay attention to, rehearse and remember, making learning less effective (Sweller, 1988).

John Sweller and other researchers have identified ways in which cognitive load can be reduced in a learning environment using more effective teaching methods, thus encouraging the formation of new memories.

Types of Cognitive Load

Cognitive load takes one of three forms: it may be intrinsic, extraneous or germane.

  • Intrinsic Cognitive Load
    This type of cognitive load refers the demand made of a learner by the intrinsic quality of information being learnt. The load exerted on a learner depends on the complexity of the task set or concept being presented, and a learner’s ability to understand the new information.

    The intrinsic nature of such a cognitive load makes it difficult to eliminate: you will always find a difficult, new activity (e.g. solving a complex equation) more challenging than a simple task (e.g. adding two small numbers together).

    However, the cognitive load resulting from a complex task can be reduced by breaking it down into smaller, simpler steps for a learner to complete individually.

    You are probably familiar with task of assembling flat-pack furniture, for instance. Rather than assembly instructions containing just one large diagram showing how each piece fits together, the manufacturers simplify the process, splitting it into short step-by-step tasks. In doing so, they ensure that a customer needs only grasp these easy-to-understand tasks (e.g. screwing a screw) as opposed to visualizing the entire process of assembling a desk, in order to set it up. They are also able to focus only on the 2-3 parts that they need to use in any one step, rather than a whole box of wooden parts, nails, and other fixings.

  • Extraneous Cognitive Load
    Extraneous cognitive load is produced by the demands imposed on learners by the teacher, or the instructions that they are asked to follow. This type of cognitive load is extraneous to the learning task, and is increased by ineffective teaching methods, which unintentionally misdirect students with distracting information or make a task more complex than it needs to be.

    Effective presentation methods can help reduce the extraneous cognitive load imposed on a learner, instead freeing them to rehearse and remember a lesson.

    For example, some types of information are better understand when illustrated in a diagram, as opposed to being written. The rotation of the moon as it orbits the earth, for instance, is easier to comprehend when demonstrated visually, using a model of the solar system or a video, rather than in a written form without diagrams. The visual presentation of concepts such as the solar system mean that a learner does not have to keep hold of ideas explained early on in a paragraph of text in order to understand the final sentence. Instead, they can be referenced simply by looking at an illustration.

  • Germane Cognitive Load
    This third type of cognitive load is produced by the construction of schemas and is considered to be desirable, as it assists in learning new skills and other information.

    A memory schema is a conceptualisation of a particular idea or object which tells us what to expect when we encounter it in the future.

    We hold schemas for people, household objects and ‘script’ schemas for routines and events such as our morning routine, as well schemas for particular ‘roles’ that we find people enacting, which tell us what kind of behavior to expect of them.

    The first time we experience something new (e.g. attending a first wedding) can be daunting, as we do not have a schema that tells us what to expect, and so a germane cognitive load is produced as we observe and learn about the experience to help us to anticipate and understand it in the future.


Cognitive load theory can be applied to any instructional learning context: by minimising the extraneous cognitive load imposed on students and avoiding a means-end analysis of a task, which can lead learners to be overwhelmed by the complexity of an idea, teachers can ensure that the presentation of information does not impede learning.

Furthermore, by developing activities which encourage a germane cognitive load, you can better facilitate long-term knowledge and skill acquisition.

The potential applications for cognitive load theory reach far beyond traditional learning situations such as classrooms, lecture rooms and conferences. Whilst teachers can use CLT to help students to learn, you can also apply the theory when giving a speech or presentation. By simplifying the ideas you want to convey, providing individual, easy-to-understand explanations of each issue and removing superfluous details, you can reduce extraneous cognitive load to make your presentation more memorable to listeners.

Let’s take a look at some specific ways in which you can apply cognitive load theory:

Worked Examples

John Sweller (2006) emphasised the use of worked examples to show learners how to carry out new tasks. A worked example is essentially a step-by-step demonstration where a process is reduced to single actions, reducing the intrinsic cognitive load resulting from a complex task.

For example, maths teachers use worked examples to show students how to use long division, which from the outset may appear difficult, but when split into simpler steps, can be understood by most people. Online instructional videos for DIY projects, where a task is broken down into smaller assignments and demonstrated by an expert, are another instance of worked examples.


According to the working memory model, auditory data is processed separately to visual information. A ‘phonological loop’ handles speech and other sounds, whilst a distinct ‘visuo-spatial sketchpad’ processes text and other visual stimuli (Baddeley and Hitch, 1974). When a learner is presented with two simultaneous instances of the same type of stimulus, extraneous cognitive load is increased and as the two compete for attention.

For example, when you hear two people trying to explain something to you at the same time, the increased cognitive load prevents you from focussing on both explanations and you might only pick up on fragments of what each person is saying.

Similarly, when a diagram printed in a book is labeled with different numbers, and each number is explained in paragraphs printed on the opposite page, the need to cross-reference each number across two different visual stimuli increases the cognitive load experienced by a learner and hinders their effort to understand the information.

Split-Attention Effect

Cognitive load theory suggests that educators remove competing stimuli in order to avoid the split-attention effect, and should allow students to focus on a single visual source of information at any given time. Similarly, when listening to a lecture or watching an instructional video, the experience should not be interrupted with competing explanations of an idea.

Paul Chandler and John Sweller demonstrated this in a study which concluded that the learning experience could be improved when competing stimuli were merged into one source of information.

By embedding a written explanation of a diagram within the illustration itself, the researchers found that learners could understand the information presented to them better than if the diagram and explanation were provided separately (Chandler and Sweller, 1992).

Similarly, in a presentation to show students the locations of different countries on a world map, a teacher might employ these findings by writing the names of the respective countries on the map rather than asking students to refer to a separate key listing the countries by number.

However, as Baddeley and Hitch’s theory infers that audio and visual stimuli are processed separately, they can be combined in order to provide an enhance learning experience.

A visual demonstration of a task presented in a video can therefore be improved with an audio narration that explains each step, without overloading viewers with competing stimuli.


The split-attention effect can also affect an audience when distractions are present in the learning environment.

Just as the light from an audience member’s phone can lead your attention away from the screen at a cinema, we are all prone to losing focus in a learning environment when distractions are present.

By identifying and removing stimuli which may distract an audience, educators can reduce the additional extraneous cognitive load imposed them. When giving a presentation, a lecturer might ensure that they do not stand next to distracting signs or posters. A co-operative, quiet audience can also reduce cognitive load and help to avoid the irrelevant speech effect, whereby distracting background sounds have been found to impede the formation of new memories (Jones and Macken, 1993).


New report on Cognitive Load Theory aimed at teachers (CLT).

By Greg Ashman:

I have been researching Cognitive Load Theory (CLT) for a couple of years now. During that time, I’ve blogged about CLT and I’ve often been asked if there is a teacher-friendly summary of the theory available.

Today, such a summary has been released by the New South Wales Centre for Education and Statistics (CESE with handle @nswcese on Twitter). It’s a pretty good take on CLT. John Sweller has read it and thinks they’ve managed to capture the essence of the theory pretty well.

The CESE paper looks at the principles of CLT and the main findings as they apply to teaching, including a brief description of the different ‘effects’ that have been noted. It also has a helpful section on criticisms and limitations (CLT is the subject of ongoing research). I strongly recommend the CESE paper to any teachers who are starting to dip their toes in the water.

It’s pleasing to see the number of popular descriptions of CLT increase in recent times. There are my own blog posts, of course, as well as a piece I wrote for The Conversation. In addition, we now have an interesting paper by Sweller that covers similar ground to the CESE paper while placing it in a chronology of how CLT developed. And thanks to the researchED movement, we also have a video of Sweller explaining the key ideas.

However, the best resource for those who want a complete picture of CLT is still a rather expensive book. Hopefully, in time, we will also have a popular version of this.

Cognitive Load Theory – every teacher should know this!

Cognitive Load Theory

It was around 18 months ago that I first came across Cognitive Load Theory (CLT). Recently CLT has gained a lot of traction on social media; helped by the fact that Dylan Wiliam cited it as the most important thing for teachers to know earlier this year:


Oliver Caviglioli also recently created one of his fantastic illustrative summaries on Sweller’s book and this reignited the CLT flame for me. A few weeks ago I posted about CLT on the Society for Education and Training’s Blog, in an attempt to further promote what I and many others consider to be an essential learning theory. I thought I’d share it on my blog in an attempt to reach a few more practitioners, so here it is:


What is the one learning theory that I feel all teachers should be made aware of?

Cognitive Load Theory (CLT) – Coined in 1988 by John Sweller, this theory posits that our working memory is only able to hold a small amount of information at any one time and that instructional methods should avoid overloading it in order to maximise learning (Sweller, 1988).


Why have I chosen this theory?

We’ve all been in learning sessions where the teacher has whizzed through the content, leaving us with little to remember. We’ve also been in those sessions where the content is so complex that we leave more confused than when we entered. CLT goes some way to explaining why this happens and what we, as teachers, can do to maximise the learning of individuals within our classrooms.
Building on the work of Baddeley and Hitch (1974), CLT views human cognitive architecture as the working memory and long term memory. Put simply, the working memory has a limited capacity and consists of multiple components that are responsible for directing attention and coordinating cognitive processes. Long term memory on the other hand, has an endless capacity for storage and works with working memory to retrieve information (Baddeley, 2003).

What can teachers do to reduce cognitive load?

  • Activate prior knowledge before sharing new information with students – Our long term memory is said to have a number of organised patterns of knowledge (known as schema). Each schema acts as a single item in working memory, so can be handled easier than having lots of new, isolated information. Through retrieving information from the long term memory via quizzes, visual aids and discussions, students can bring crucial information to working memory (see image 1) and assimilate new information to build upon what they already know (Baddeley, 2003). Activating prior knowledge is also supported in the work of Marzano, Gaddy and Dean (2000), who found a substantial improvement in achievement (0.59ES). Furthermore, retrieval practice has shown to strengthen our retention of the information (Wenger, Thompson and Bartling, 1980) – a win win!

  • Use visual and verbal information to present information to students – This has nothing to do with the infamous ‘learning styles’, rather empirical research suggests that our working memory has two points of entry (Chandler and Sweller, 1992). One accepts auditory information, whilst the other visual. If the auditory and visual information correspond to one another, then the burden on working memory is far less than using one pathway alone. Image 1 shows the effect of using one pathway to working memory, whereas image 2 shows the use of both. However, please note that if the text and visual information are not clearly integrated, then it could have adverse effects on learning (Chandler and Sweller, 1992).

  • Use worked examples and models to support learning – There are a wealth of studies that have shown the positive impact of using worked examples to enhance learning (Chandler and Sweller, 1991). According to Clark, Nguyen and Sweller (2006, p.190), ‘a worked example is a step-by-step demonstration of how to perform a task or how to solve a problem’. These steps provide learners with direction and support to create mental models of how to tackle a problem/task, or what ‘good’ looks like. Discovery or problem-based learning on the other hand can be burdensome to working memory due to learners having insufficient prior knowledge to draw upon to support their learning. Moreover, the vast amount of information they have to consider in completing work independently can result in a struggle to direct their attention. As learners develop a greater understanding of the topic, elements of the worked or modelled examples can be ‘faded’ (removed) to foster greater independence.

Worked Example


In summary, regardless of one’s philosophical predisposition, I argue that all teachers need to have an awareness of the potential benefits and limitations of the ways in which they present learning opportunities for learners. CLT and the associated empirical research provides us with an understanding of how we process, organise and store information most effectively and for this reason, all teachers should acquire a basic understanding of the premise.

Blog by @FurtherEdagogy

Baddeley, A.D. (2003). Working memory: looking back and looking forward. Nature Reviews Neuroscience, 4, p.829-839.

Baddeley, A.D. and Hitch, G. (1974). Working Memory. Psychology of Learning and Motivation, 8, p.47-89.

Chandler, P. and Sweller, J. (1991). Cognitive Load Theory and the Format of Instruction. Cognition and Instruction, 8 (4), p. 293-332.

Chandler, P. and Sweller, J. (1992). The split-attention effect as a factor in the design of instruction. British Journal of Educational Psychology, 62 (2), p.233–246.

Clark, R.C., Nguyen, F. and Sweller, J. (2006). Efficiency in learning: evidence-based guidelines to manage cognitive load. San Francisco: Pfeiffer.

Marzano, R.J., Gaddy, B.B. and Dean, C. (2000). What works in classroom instruction. Aurora, CO: Mid-continent Research for Education and Learning.

Sweller, J. (1988). Cognitive Load during Problem Solving: Effects on Learning. Cognitive Science, 12, p.257-285.

Wenger, S.K., Thompson, P. and Bartling, C.A. (1980). Recall facilitates subsequent recognition. Journal of Experimental Psychology: Human Learning and Memory, 6 (2), p.135-144.