working memory model

• working memory model (WMM)


  created by Baddeley and Hitch to replace the STM store of the MSM due to criticism of the STM

  • short term memory must be more complex than just a single store transferring information into the long-term memory. Due to the way that we use short term memory they felt that it must be an active processor, holding multiple pieces of information whilst those pieces of information are being worked on.
• central executive 


  • This is the director/head of the model and receives and filters the information before passing it on to two ‘slave’ systems. The Central Executive is limited in capacity, so it can only hold one piece of information at a time. It switches attention between different inputs.
• phonological loop


  • The phonological loop processes auditory coded information. It has a limited capacity (what can be said in 2 secs) and 2 second duration, so confusion can occur between similar sounding words.
  • It is split into the primary acoustic store (‘inner ear’, dealing with sounds recently heard and holding those in your short-term memory) and the articulatory process (‘inner voice’, keeps information in your mind subvocal repetition).
• visuo-spatial sketchpad

  • The visuospatial sketchpad is your ‘inner eye’. It has a limited capacity and 2 second duration, and stores visual and spatial information.
  • This consists of the visual cache and Inner scribe. The visual cache is a passive store of form and colour of objects,
  • and inner scribe is an active store allows you to visualise the relationship between objects and rehearse what you have seen. 
• episodic buffer 


  added to WMM in 2000

  • general store to hold and integrate information from visuospatial sketchpad, phonological loop and central executive and then can pass that information into the long-term memory
  • deals with all information
  • limited capacity
• Baddeley (central executive)


  • participants were asked to verbally generate random lists of numbers while also attempting to switch between typing numbers and letters on a keyboard. Baddeley found that compared to typing or generating a list of number on their own, participants performed considerably worse when completing both tasks at the same time. This shows that people have low aptitude for dual task performance, perhaps because the central executive is limited in capacity and can only cope with one type of information at a time.
• Shallice and Warrington (KF)


  investigate clinical case of KF

  • found KF has selective impairment to verbal short term memory cause by a brain injury, however visual functioning of his STM is not affected
  • this suggests the PL and VSS are separate processes located in separate brain regions
• (weakness) not fully falsifiable

  • The central executive has been criticised by other psychologists as a vague concept without full explanation of its function and is quite difficult to test (not fully falsifiable). Baddeley admits that the concept needs development, and included the episodic buffer as part of this development.
• (weakness) mundane realism 


  • Results from laboratory experiments researching the WMM will often have low mundane realism  (i.e. may not relate to real life), as tasks such as repeating ‘the the the’ are arguably not representative of our everyday activities, so can’t be generalised to memory in day to day life.
• (strength) replicability 


  • The model was developed based on evidence from laboratory experiments, so confounding variables could be carefully controlled to produce reliable results (that can be replicated).
• (strength) neuroscanning evidence

  such as that provided by Braver et al, has demonstrated a positive correlation between an increasing cognitive load processed by the central executive (as marked by increasing task difficulty) and increasing levels of activation in the prefrontal cortex. This supports the idea that the central executive has the role of allocating tasks to slave systems and has a limited processing capacity, as reflected by the increased brain activation levels, thus suggesting that the WMM is accurate in its mechanism of the central executive.