Working memory model

• Concepts of working memory model

  • Introduced by Baddeley and Hitch in 1974
  • A model explaining how the STM works
  • Does not try to explain how LTM works
  • Suggests that the STM is a dynamic processor of different types of information using sub-units co-ordinated by a central decision making system
• Why did Baddeley and Hitch think STM is not just one store?

  • Dual task performance
  • If you do 2 things at the same time and they are both visual or auditory you perform them less well than if you were to do them separately.
  • if you do 2 things at the same time and one is visual and one involves sound you do them as well simultaneously as you do separately.
• Dual task technique

  • If you do 2 tasks at the same time using the same senses e.g 2 visual tasks, you perform less well than doing them separately.
  • If you do 2 tasks at the same time, but one is visual and one is acoustic there is no interference. So you do then just as well simultaneously as you would separately.
  • Suggesting there are 2 separate stores, one for visual processing and one for auditory processing,
• Central executive

  • Attentional system
  • Controls attention and co-ordinates the actions of 2 subsystems
  • Modality free- codes all senses
  • Can briefly store information but has a limited capacity of around 4 items
  • Considered to be the most important part of WMM (decision-making, attention, passes information and controls other systems)
• Phonological loop

  • Deals with auditory information.
  • Limited capacity of what can be said in 2 seconds
  • Made up of: Articulatory process, phonological store
• Articulatory process (inner voice)

  • Rehearses information verbally (maintenance rehearsal)
  • used for words we hear or see
• Phonological store


  Stored words we can hear
• Visuo-spatial sketchpad

  • Deals with visual and spatial information.
  • Visual: What things look like
  • Spatial: Relationships between things e.g distance
  • Limited capacity of 3/4 objects
  • Separated into visual cache, inner scribe (Logie)
• Visual cache

  • Stores visual data e.g colour
• Inner scribe


  Spatial information like arrangement of objects
• Episodic buffer

  • Not part of original model, added by Baddeley
  • Role is to be a temporary store where visual, spatial and verbal information is integrated.
  • Limited capacity of 4 chunks of information
  • Maintains a sense of time sequencing, basically recording events that are happening.
  • Links working memory to LTM.
• Brain scanning support

  • Braver et al, gave participants tasks that involved the central executive while performing a brain scan. Researchers found greater activity in prefrontal cortex. Additionally when the task becomes harder, the activity in this area increased more.
  • Shows different memory functions are handled by different areas in the brain. Also supports the model’s prediction that there will be more activity in central executive as more demands are placed upon it so the central executive must work harder to fulfil that function.
  • Strengthens role of central executive.
• Lack of clarity of central executive

  • Eslinger and Damasio, studied patient EVR who had his cerebral tumour removed. When tested, EVR performed well on tests requiring reasoning, which suggested that his central reasoning was intact, however he had poor decision-making skills where he would spend hours trying to figure out what to eat.
  • Shows as his central executive was not fully intact, it is more complex than WMM suggests
  • Central executive may consist of several components and not just a single component.
• Supporting evidence from dual task performance studies

  • Baddeley showed that participants had more difficulty doing 2 visual tasks than doing a visual and verbal task at the same time.
  • This helps explain the increased difficulty of completing 2 visual tasks as they are both competing for the same sub systems, whereas when they did a verbal and visual tasks together there was no competition.
  • Dual tasks studies provides evidence for the existence of multiple components within the STM and support the idea of separate phonological loop and visuo-spatial sketchpad.
• Case study support

  • Shallice and Warrington conducted a study on patient KF, who suffered from a motorcycle accident. patient KF had poor short-term memory ability for verbal information e.g difficult with sounds, however his visual information remained intact.
  • findings suggests there must be a STM store which processes visual information according to WMM is the visual-spatial sketchpad. Whereas the phonological loop deals with auditory information. With reference to patient KF, according to WMM the phonological loop had been damaged however his visual-spatial sketchpad was still intact