working memory model

• Working memory model = an explanation of how short-term memory is organised and how it functions
• The central executive has a 'supervisory' role. It monitors incoming data, focuses and divides our limited attention and allocates 'slave systems' to tasks.
• The central executive has a very limited processing capacity and does not store information.
• One of the slave systems is the phonological loop. It deals with auditory information and preserves the order in which the information arrives.
• The phonological loop is divided into:

  • the phonological store (stores the words you hear)
  • the articulatory process which allows maintenance rehearsal
• The second slave system is the visuo-spatial sketchpad. The VSS stores visual and spatial information.
• The visuo-spatial sketchpad has a limited capacity, which according to Baddeley is about 3 or 4 objects.
• Robert Logie subdivided the VSS into:

  • the visual cache (stores visual data)
  • the inner scribe (records the arrangement of objects in the visual field)
• The third slave system is the episodic buffer. It is a temporary store for information, integrating the visual, spatial and verbal information processed by other stores and maintaining a sense of time sequencing (basically records events that are happening).
• The episodic buffer can be seen as the storage component of the central executive and has a limited capacity of about 4 chunks.
• Shallice and Warrington's case study of KF supports the existence of separate visual and acoustic memory stores. After his brain injury KF had poor STM ability for auditory information but could process visual information normally. KF's phonological loop was damaged but his visuo-spatial sketchpad was intact.
• However, it is unclear whether KF had other cognitive impairments which might have affected his performance on memory tasks. His injury was caused by a motorcycle accident. The trauma involved may have affected his cognitive performance quite apart from any brain injury. This challenges evidence that comes from clinical studies of people with brain injuries that may have affected many different systems.
• Studies of dual-task performance support the separate existence of the visuo-spatial sketchpad. When Baddeley's participants carried out a visual and verbal task at the same time their performance on each was similar to when they carried out the tasks separately. But when both tasks were visual, performance on both declined substantially. This is because both visual tasks compete for the same slave subsystem. This shows there must be a separate slave system that processes visual input and one for verbal processing.
• There is a lack of clarity over the nature of the central executive. Baddeley himself recognised this when he said "The central executive is the most important but least understood component of working memory.". The CE needs to be more clearly specified than just 'attention'. Some psychologists believe the CE may consist of separate subcomponents. This means the CE is an unsatisfactory component and this challenges the integrity of the WMM.