By Andy Tharby
This post is a quick and simple introduction to John Sweller’s Cognitive Load Theory for teachers. It will seek to answer the following three questions:
1. What are working memory and long-term memory and what roles do they have in learning?
2. What is Cognitive Load Theory?
3. How can teachers better design lessons and resources so that cognitive load is reduced?
A simple model of human cognition consists of two related types of memory:
Long-term memory. This is a huge storehouse of vocabulary, concepts and procedures that can be likened to a filing cabinet or hard drive. Here memories are stored and organised in ‘schemas’.
Working memory. This is the limited space in which we think and process information, analogous to a page on a notepad or the processor on a PC. Most researchers agree that the (magic number) four is the maximum number of new pieces of information that can be thought about at any one time. For challenging tasks and content, this capacity is likely to be lower.
One of the aims of education is to transfer information from the working memory to the long term memory. Yet there is a problem, known as the ‘bottleneck’. If working memory becomes overloaded then new information is less likely to enter the long-term memory.
The aim, therefore, is to ensure that cognitive load – the quantity of information a student is holding in their working-memory at any one time – is maintained at a commodious level.
There are three aspects of cognitive load which are usually considered to work in tandem.
Intrinsic load is related to the inherent difficulty of the subject matter being learnt. It is influenced by how complex the material is and how much a student already knows about the topic. For example, 2 + 2 + 4 has less intrinsic load than 93 x 543, whereas understanding the workings of the human respiratory system has more intrinsic load than knowing where the lungs are situated in a human body.
Extraneous load is any extra and unnecessary thinking that students have to do that does not contribute to learning. Unlike intrinsic load, extraneous load is related to how the subject material is presented rather than its inherent difficulty. As teachers, we can either heighten or reduce its effect.
The third type of cognitive load, germane load, is desirable. It is the load placed on working memory that contributes directly to genuine learning – the nourishing and productive thinking that causes our students to form and consolidate long-term memories.
It is important to note that there are no reliable studies (yet!) that have reported ways of creating genuine and durable changes to a child’s working memory capacity. Rather like height or eye colour, it seems that we are stuck with that we have been born with. Some students have significantly less capacity than others; however, it remains true that all of us have a limit to the amount we can think about at once.
To combat working memory deficiencies we can …
1. Outsource working memory by providing scaffolding that fades away incrementally.
2. Provide the conditions that help students to practise key skills and concepts to automaticity.
3. Centralise the development of long-term memory through careful curriculum planning.
Day-to-day planning, resourcing and teaching may be enhanced if we try some of the following approaches:
1. Teach in short bursts followed by practice. If a process consists of many parts, then these should be grouped together and taught in separate chunks. We should isolate the parts, teach them and then provide opportunities for practice before we bring them together as a whole.
2. Avoid split attention. Strain is placed on working memory when a child has to mentally integrate information from different places. Resources should include colour-coding, integrated labels and arrows. Related pieces of information should be placed in close physical proximity.
3. Reduce redundant information. Remove superfluous images and text from PowerPoints and other resources. Try to ensure that students are not expected to be listening to a teacher and reading text at the same time, and avoid speaking over the top of students whilst they are thinking about something else. Give lean and focussed feedback.
4. Limit distraction. Cognitively challenging tasks should usually be completed in silence. Avoid too much sensory stimulation during tasks like extended writing or solving complex, multifaceted problems.
5. Use worked examples. These are completed or partially completed problems or tasks that students study before and during the initial teaching of a new skill or process. These should be gradually faded away so that students gain independence.
6. Dual coding. Dual coding theory holds that if material is present in visual and verbal forms simultaneously then it is likely to improve learning, but will not cause cognitive overload.
To finish, it is important to reassert that the implementation of these strategies should not lower expectations or reduce the inherent challenge and vision of the curriculum. The scaffolding and support should always be gradually reduced – and re-instigated only if learning is incomplete or misconceptions remain. The philosophy should persist that all students can learn anything, so long as lesson material is presented in a concise, logical and sequential fashion with lots of opportunities for practice. And, of course, so long as students remain motivated to learn.
The mantra ‘less is more’ should guide our thinking about cognitive load.