The impact of cognitive load on working memory

George Miller (1956) famously coined the magic number seven when it comes to how many items we are able to hold and manipulate in our working memory.  Though, his contemporaries say that it is more around four (Cowan, 2001), its importance to learning in the classroom appears  overlooked by teacher training and teachers.  This is in spite of growing evidence to suggest that working memory can significantly impact student learning. Surely the role of working memory in schooling should be considered, in particular  how limiting cognitive load can greatly enhance it.

What is working memory?

Working memory is commonly used interchangeably with short-term memory. However, Cowan (2008) suggests that a distinction exists, summarising that working memory measures have been found to correlate better with intellectual aptitudes than short-term memory measures. Thus, suggesting that working memory incorporates not only storage capacity but features processing capabilities. Therefore, many psychologists define working memory as the ability to hold and manipulate information (Gathercole and Alloway, 2007).

Imagine, for example, that I ask you to spell the word cat. First you would retrieve the word cat from your long term memory and then hold it in your short-term memory. You would then apply your language rules to spell out c-a-t. Most likely, you would not have been able to notice working memory in practice because the spelling of cat is now automated. You are more likely to notice the distinction if I then asked you to spell cat backwards t-a-c. This is because it’s not automatic, so you bring forward the word cat from your long term memory, hold it in your short term memory and then flip it around and think carefully how it is spelt backwards which is presumably slower than spelling in forward. Now imagine learning how to spell cat for the first time, the students working memory space would quickly fill up.

What is the impact of cognitive load on working memory?

If working memory is theoretically the ability to hold and manipulate information in four or five slots then cognitive load is when the slots become full. When working memory has reached its limit then new information can no longer be processed. For instance, learning to spell dog a student will have to apply letter recognition, decoding, phonics and many more literacy functions in order to spell dog correctly. This can be daunting for any young student, even more so if the student becomes dispondent which may impede on automation of key linguistic rules that may contribute to long term learning gaps.  However, teachers can play a role in limiting the impact cognitive load has working memory to aid learning.

Sweller (1988) hypothesises that cognitive load exists in three forms: intrinsic, extraneous and germane. As teachers we can control for extraneous cognitive load which consists of the information we provide and want to plan to encourage germane cognitive load that is devoted to automating schemas. As a result our planning needs to not only consider what is required to be taught but also how it is planned. Careful planning that automates knoweldge can limit cognitive load and allow students to engage in more complex learning. If learning the word cat and dog are automated then it is not necessary for working memory to break down each letter and sound, instead all the processes are chunked and act as one item.

Sweller suggests five planning strategies that limit cognitive load on working memory:

  1. Chunking
  2. Worked examples
  3. Split attention
  4. Backward Fading
  5. Expertise reversal

The evidence suggests that working memory plays an important and critical role in how we learn. It allows us to manipulate information by turning it 360 degrees to reorganise or construct new knowledge schemas which provide a powerful platform for learning. Students then can apply knowledge to more complex thinking and make links or draw inferences between different concepts or fields of knowledge. Therefore, lesson planning is critical not only for knowledge selection but also considering the impact cognitive load has on a student’s working memory to learn the intended knowledge.



Cowan, N. (2001). The magical number 4 in short-term memory: A reconsideration of mental storage capacity. Behavioural and Brain Sciences, 24: 87 – 114.

Cowan, N. (2008). What are the differences between long-term, short-term, and working memory? Progress in Brain Research, 169: 323–338.

Gathercole, S. and Alloway, T. (2007). Understanding Working Memory: A Classroom Guide, Harcourt Assessment: London

Miller, G. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. The psychological review, 63: 81-97.

Sweller, J. (1988). Cognitive Load During Problem Solving: Effects on Learning. Cognitive Science, 12: 257–285.


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