CENTRAL EXECUTIVE
The central executive is the control centre responsible for coordinating the other slave units. It is able to process information from any of the senses and appears to have a minimal storage capacity. We use the central executive when we are concentrating on a task and it is sometimes likened to ‘attention.’ If we are attempting to do two things at the same time, for example read and hold a conversation, it is the central executive that switches our attention between the two, deciding which other components of the working memory to use.
PHONOLOGICAL LOOP
The phonological loop consists of two parts, the articulatory control system and the phonological store:
Articulatory Control System (The Inner Voice) The articulatory control system rehearses information verbally and has a time based capacity of about 2 seconds. It is helpful to think of it as the system that you use to mentally rehearse information by repeating it over and over again.
Phonological Store (The Inner Ear – but not to be confused with the canals in your actual ear) The phonological store uses a sound based code to store information, but this information decays after about 2 seconds, unless it is rehearsed by the articulatory control system. The phonological store receives its input either directly from the ears or from long term memory.
VISUO-SPATIAL SCRATCHPAD
The visuo-spatial sketchpad stores and manipulates visual information; input is from the eyes or long term memory. If you imagine an object and then picture it rotating you are using your visuo-spatial sketchpad.
EPISODIC BUFFER
The episodic buffer was a late addition to the working memory model and was added by Baddeley in 2000. The central executive has no storage of its own and the other two stores hold either visual or auditory data. Baddeley realised that there needed to be a store that could hold and coordinate information from all three other stores as well as from LTM. Its purpose is to bind together all of the information from the other components of working memory with information about time and order. This prepares memories for storage in episodic long term memory.
EVIDENCE TO SUPPORT THE WORKING MEMORY MODEL
The KF Case Study supports the Working Memory Model. KF suffered brain damage from a motorcycle accident that damaged his short-term memory. KF's impairment was mainly for verbal information - his memory for visual information was largely unaffected. This shows that there are separate STM components for visual information (VSS) and verbal information (phonological loop).
STRENGTHS
This working memory model seems perfectly realistic because it ties in with the manipulation of information when problems are encountered and solved. It seems more plausible than the Atkinson-Shiffrin model which claims STM is a static store. Baddeley and Hitch’s model shows STM to be a dynamic process. In a 1997 piece, Baddeley stated that mentally counting the windows on a house is an example of the working memory model in action.
This process begins with a visualization of every window which corresponds with the Visuo-Spatial Sketchpad of the model. The counting of each window brings the Phonological Loop into play while the Central Executive coordinates all of this activity.
WEAKNESSES
The primary part of the working memory model is the Central Executive which is still not clearly explained nor understood. Its functions are unclear and extremely difficult to test. Baddeley states that the Central Executive only has a limited capacity but at present, there seems to be no way to separate it to find out conclusively. He also claims that it is possible to divide the Central Executive into smaller systems but has thus far failed to positively do so.
The Episodic Buffer which was brought into the equation remains a mystery to researchers in terms of how it binds together information from the model’s other parts and LTM.