Working Memory
Jonathan Firth's Memory & Metacognition Updates #70
Considering that this is my 70th update, it’s surprising that I haven’t previously done a deep dive into working memory. I’ve mentioned it often enough, but today I thought it was time to explore this system a little more.
I mentioned last time that the familiar ‘modal model’ of memory is limited in showing working memory as a single process, and not fully accounting for the different types of information we can process.
The modal model also views the role of attention as getting things into WM, but doesn’t consider its function after that.
Baddeley’s Model
Baddeley and Hitch (1974) provided a much more detailed exploration of working memory as an active system, and one which is still being developed to this day.
They started by setting out three key WM processes – visual, verbal, plus a control process they called the central executive. By calling it their ‘working memory model’, it was clear from the start that the emphasis was on how people performed tasks, rather than just briefly storing information.
The central executive was at the heart of everything, and was based on attention – which is, of course, limited.
Baddeley and Hitch didn’t include long-term memory in the model at all! This is obviously a limitation, but it was another indication that WM was not being viewed merely as a stepping stone in the process of taking in new knowledge.
Later Versions
Since then, Alan Baddeley has worked with various researchers to refine the model further, and to explore that link with LTM. Key changes include:
After a series of experiments, it became clear that verbal WM needed to be divided into two parts: a phonological store which responds to sound, and a rehearsal loop (active when you say a few numbers repeatedly in your head, for example).
In 2000, they added a further system: the episodic buffer. This is responsible for combining different sensory information into meaningful experiences that can be retained as episodic memories.
Later writings also explore the link with LTM, though the details of how new information is encoded is, arguably, still a limitation of the model.
Uses of the Model
So, is the model useful? In my view, it is one of the best summaries of how working memory operates, and has practical implications for educators.
It also describes the limitations of working memory more specifically than other models do. It views a span for words/digits as being based on time (around two seconds to mentally rehearse items) rather than number of items. The episodic buffer is considered to be limited to around four meaningful chunks.
The model is helpful in understanding multi-tasking. We know that this is demanding for learners, but Baddeley’s model shows two key reasons why. One is the limited attention span that guides all of the other systems in WM. The other is that while each sub-system has its own unique limits, multi-tasking of relatively automatic tasks within different systems (e.g. one verbal and one visual task) is possible.
Marc Smith and I made the model the focus of Chapter 2 of Psychology in the Classroom, and you can download and read the chapter for free here.
The paper below by Baddeley himself is a great summary of the model that delves into more detail regarding things like how it was developed, the neuroscience evidence, and how it differs from Atkinson & Shiffrin’s modal model.
Baddeley, A. (2010). Working memory. Current Biology, 20(4), R136–R140.
That’s all for now – hope you have a great week!
Jonathan
Last week: Simplistic Assumptions About Memory
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