Working Memory
Working memory is merely another name for short term memory, however it is given this name because it's function is far more complicated than a simple store as was suggested in the multi-store model.
Below we have a diagram which represents how this memory system is believed to work.
Central Executive
Relatively little is known about this part of the working memory, but it is thought to be the 'boss' of the working memory: selectively attending to some stimuli whilst ignoring others and retriving information for use by the working memory.
Phonological Loop
As you can see in the diagram, this system is made up of two components:
The phonological store, this holds (stores) information that is either speech or sound related, however memory here lasts for a very short amount of time, only about two seconds. This component is also known as the inner ear.
The articulatory loop (also articulatory control system) is a process for rehearsing the information and therefore keeping it in the loop. This part is know also as the inner voice. This is how a tune can get stuck in your head: it is continuously rehearsed by the 'inner voice', thus preventing it from leaving the working memory.
Evidence for the existence of these two separate components is in a 1993 study by Paulesu et al:
| Aim | To investigate the nature of the phonological loop and working memory. |
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| Method | Participants either stored a series of letters or mentally rehearsed the sounds of letters. Whilst doing this, the blood flow in their brains was recorded using positron emission tomography (PET). |
| Results | They found that blood flow was quite different depending on the two types of task. |
| Conclusion | The results support the theory that the phonological loop has two different components: one for storage and one for rehearsal. |
Visuo Spatial Sketchpad
This component manipulates visual information, for example: imagine your bedroom and where the window is.
It can also be called the 'inner eye' because it enables you to mentally see things without looking at them. Some research into it was done by one of the men who originally proposed the working memory: Alan Baddeley.
| Aim | To try and find evidence for a visuo-spatial sketchpad with a limited storage system. |
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| Method | Participants tracked a moving spot of light. At the same time they classified the angles in the letter 'F' virtually (i.e. a task that uses the visuo-spatial sketchpad as well. |
| Results | The participants found it very difficult to track the light and classify angles at the same time. However it was far easier to track the light when given a verbal rather than visualisation task. |
| Conclusions | The tracking and imagining tasks were both competing for the limited resources of the visuo-spatial sketchpad so performance was impaired. However with the verbal task, the resources of the phonlogical loop were used. |
Evaluation
Firstly there is a final study I need to mention: Baddeley and Hitch (1976), they got participants to undertake reasoning tasks, thought to involve the central executive whilst at the same time doing another task, or nothing. They found that performance was impaired when making up random numbers, also involving the central executive. So in conclusion, working memory is a general exeutive system with a limited capacity for processing.
Working memory is concerned with not just storage (as the multi-store model is) but processing as well.
On the downside though, little is known about the central executive, and no precise details are available about it; this arguably hinders understanding of the entire system since the central executive is supposedly in the middle of all processing.