“My problem is that I have been persecuted by an integer.” That’s how psychologist George Miller began his groundbreaking account of short term memory capacity in 1956 (read his original paper here). That integer was 7, the “magic number” that kept appearing in research on our ability to process incoming information.
Short term memory stores information collected from our senses. This may be transferred to our long term memory, or may be lost. From his own research and that of others, Miller concluded that the capacity of our short-term memory is limited to 7 +/- 2 items. The reason why we lose some information before it can be transferred to our long term memory is usually because it is displaced by new incoming information.
Cognitive psychologists Alan Baddeley and Graham Hitch then developed the model of a simple memory store into the concept of working memory, but the principle of a limited capacity remains. Teachers need to be aware of this in presenting students with new subject content. A feeling of being overwhelmed by new information isn’t because our brain is ‘full’ but rather because the capacity of our working memory to process new information is being exceeded. An understanding of the limits of working memory can help teachers plan accessible learning activities for all students and also recognise those who have poor working memory.
In general, we should think about how much information is presented at once and how many items, or instructions in a sequence, students have to recall without prompts in order to complete a task. Most of us would struggle beyond 7 for an unfamiliar task, and some students will not readily recall this many. Examples where teachers should consider this in the design of resources and tasks include:
- The layout of presentation slides and the number of items on each
- The number of options or menu items in electronic / online resources
- The layout of activity sheets – how much information is presented at once
- The number of steps or stages in a sequence of instructions. Should some steps be broken down further into sub-stages?
- The number of verbal instructions, repetition, and availability of non-verbal memory aids.
- What assumptions do instructions for practical activities make about students’ recollection of previous routines?
- How much do students have to remember in order to complete homework?
Much of this would be considered good advise for general planning. We have to give additional consideration for children who may have more limited working memory capacity.
Characteristics of children with poor working memory (Susan Gathercole)
- Children have good social skills but may be quiet or reserved in collaborative learning activities.
- May appear forgetful, inattentive or easily distracted in class
- May not follow through instructions or complete tasks
- Forget key content of messages, instructions or homework
If you’re like me, when reading that list you will recall children you teach who have these characteristics. It is well worth considering that the ‘inattentive’ or ‘distracted’ child may be experiencing difficulties with working memory. This can often result in poor academic progress over time. Research has focussed on reading and mathematics, but other areas of study are also likely to be affected.
On recognising these signs, there are a number of things that teachers can do to help students, including:
- Reducing the working memory load by decreasing the number of items that need to be remembered at one time, particularly by restructuring complex tasks
- increasing the meaningfulness of new material by placing it in context and the familiarity by making explicit links with prior learning and similar information of tasks that the student has encountered before
- Repeating key information frequently, using different formats
- Using memory aids as appropriate for the student, these could include key vocabulary, visual scripts, framing tools to break down tasks into stages, number lines or grids, literacy place mats, etc.
- Helping the child to develop specific strategies such as devising their own memory aids, confidence in asking for help, ‘3 before me’ resourcefulness strategies ( e.g. ‘Brain, book, buddy’), and improved organisational skills.
- Providing specific support for students in collaborative tasks, providing context and making roles and outcomes clear. I’ve written more on this in my post on ‘Making group work work’.
It is also worth recognising that our working memory capacity increases throughout childhood. For some children, the issue may be a developmental delay and with support they will catch up with their peers.
Can training improve working memory?
A considerable amount of research has been conducted into whether is is possible to train children (and adults) to improve working memory. The results are mixed, but overall this research indicates that training methods can improve short-term performance in specific tasks, but these improvements are not generalisable to other tasks or skills. This evidence suggests that our efforts as teachers may be better placed in helping students make the most effective use of the working memory they have, rather than attempting to increase their capacity.
Miller, George A. (1956) The Magical Number Seven, Plus or Minus Two: Some Limits on our Capacity for Processing Information. Originally published in Psychology Review 63: 81-97. A transcript of Miller’s lecture on short term memory capacity mentioned at the start of this post.
Gathercole, Susan & Alloway, Tracy (2007) Working memory and learning: a classroom guide. Harcourt Assessment, London. A very accessible short practical guide for teachers.
Melby-Lervåg, Monica & Hulme, Charles (2013) Is working memory training effective? A meta analysis of over twenty research studies. Developmental Psychology vol 49, 2:270-291. A meta analysis of the effectiveness of working memory training.