The Working Memory Model

• Label this:

  A) Central Executive

  B) Visuospatial sketchpad

  C) Episodic Buffer

  D) Phonological loop

  E) Articulatory control system

  F) Phonological store

  G) Long Term Memory

  
• Throughout these notes I will be referring to the Working Memory Model as WMM for simplicity :)
• The Working Memory Model (WMM) was proposed by Baddeley and Hitch (1974) it explains how one aspect of memory (Short term memory) is organised and how it is functions.
• The Working Model of Memory emerged in response to criticism of the Multi-Store Model. It questions the existence of just 1 STM store and argued that the MSM was too passive and linear; it ignored the interactive nature of memory.
• The Working Model of Memory is an active store which holds and manipulates information which the brain is actively and consciously working on. Hence the term working.
• The Central Executive (CE):

  • This is a filter which monitors and co-ordinates the operation of the other two components of the store.
  • It is an attentional process that makes decisions
  • It allocates tasks to other slave systems
  • The CE is limited in capacity and can only effectively cope with one strand of information at a time.

  
• Who supports the CE?

  Baddeley (1996) discovered participants found it hard to generate lists of random numbers while simultaneously switching between pressing numbers and letters on a keyboard. This suggests that both tasks were competing for the central executive. This supports the idea that the CE is limited in capacity and only able to cope with one type of information a time.

  
• Who else supports the CE?

  Braver et al (1975) gave participants tasks that involved the central executive while they were having a brain scan. There was greater activity in the prefrontal cortex and as the task got harder the activity in this area increased. This shows full support because as demand on the CE increases, it has to work harder to fulfil its function.
• However the CE has a....

  lack of clarity - cognitive psychologists suggest this component of the WMM is unsatisfactory and doesn't really explain anything.
• The Phonological Loop

  This is one of the slave systems that deals with auditory information. It consists of two subsystems.

  1. Articulatory Control System or 'inner voice', a verbal rehearsal system
  2. Phonological Store or 'inner ear' this memory trace lasts 1.5 - 2 seconds if not refreshed by the articulatory control system. It can also receive information directly from the sensory memory or LTM.

  The capacity of the PL is limited and determined by the amount of information that can be spoken out loud in 2 seconds.

  
• Clinical Evidence

  Shallice and Warrington (1970) case study of Patient KF who had suffered brain damage. After this damage happened, KF had poor STM ability for verbal information but he could process STM visual information i.e. he had difficulty with sounds but could recall letters and digits. This suggests his phonological loop had been damaged leaving other areas of memory intact. This supports the existence of a separate visual and acoustic store. However, evidence from other brain damaged patients may not be reliable as it concerns patients with traumatic experiences.

  
• Baddeley et al (1975)


  studied the word length effect which demonstrates that people find it more difficult to remember a list of long words (such as 'association') rather than short words. This is known as the word length effect. This is because there is limited space for rehearsal in the articulatory process (probably about two seconds worth). The world length effect disappears if a persona is given an articulatory suppression task that ties up the articulatory process. For example doing a task saying "la la la" means that your articulatory process is kept busy.
• The Visuospatial Sketchpad:


  This is one of the slave systems which holds both visual and spatial information, which can come from the sensory memory or LTM.

  As with the CE and the PL, the capacity of the VSS is also limited.
• Dual task performance Studies

  Studies of the dual-task performance support the separate existence of the visuo-spatial sketchpad.

  Baddeley et al. (1975) showed that Participants had more difficulty doing two visual tasks (tracking a light and describing the letter F) than doing both a visual and a verbal task at the same time. This increased difficulty is because both visual tasks compete for the same slave system, whereas there is no competition when doing a visual and verbal task simultaneously. This means there must be a separate slave system that processes visual input.
• • Pet scans show that different brain areas are activated when doing visual and verbal tasks which suggests the PL and VSS are separate systems which is reflected in the biology of the brain.
• Brain imaging studies

  Have also been very useful in showing the existence of individual components of working memory. Paulescu et al (1993) used PET scans to record brain activity of participants performing either verbal tasks or visual tasks, and found that very different areas of the brain were active during each task. This showed quite clearly that verbal and visual tasks are performed by different brain regions and therefore suggests that the phonological loop and visuospatial sketchpad are physically separate from each other as the working memory model suggests.
• The Episodic Buffer

  The working model of memory was updated by Baddeley (2000) after it failed to explain the results of various experiments. An additional component was added called the episodic buffer. The episodic buffer acts as a 'backup' store, which communicates with both LTM and working memory.

  The EB was introduced to explain how it is possible to temporarily store information combined from the CE, the PL, the VSS and LTM.
• Alkhalifa (2009)


  reported a patient with a severely impaired LTM who demonstrated STM capacity of up to 25 items, far exceeding the capacity of both the PL and VSS. This suggests the existence of the Episodic Buffer which holds items in working memory until they are needed.