Working Memory Model (WMM) (AQA AS Psychology)

Working memory model

• The working memory model (WMM) was proposed by Baddeley and Hitch (1974)

• Baddeley and Hitch criticised the multi-store model (MSM) as overly simplistic, particularly with regard to short-term memory (STM)

• The WMM shows that STM can be sub-divided into distinct components, and is not a unitary store (as proposed by the MSM)

• The WMM explains memories related to working on tasks that require immediate memory formation

  • Thus, the WMM refers to the 'here-and-now', STM function of memory

• There are four components of the WMM:

  • Central executive (CE)

  • Phonological loop (PL)

  • Visuo-spatial sketchpad (VSS)

  • Episodic buffer (EB)

Central executive

• The role of the central executive (CE) is to focus attention on the most important tasks that need attending to in the current moment

• The CE coordinates the three other components of the WMM by allocating them to different tasks

  • Each of the three components, phonological loop (PL), visuo-spatial sketchpad (VSS) and episodic buffer (EB) are known as 'slave systems'

• The CE has limited capacity and cannot store information

Phonological loop

• The phonological loop (PL) slave system is responsible for coordinating auditory information

  • Coding in the PL is acoustic

• The PL preserves the order in which acoustic information is processed

• There are two divisions to the PL

  • The phonological store: this component stores spoken words (the inner ear)

  • The articulatory process: this component stores written words (the inner voice)

    • Words are repeated on a loop as part of maintenance rehearsal (although these are not passed onto LTM as in the multi-store model)

• The PL has a limited capacity

Visuo-spatial sketchpad

• The visuo-spatial sketchpad (VSS) component of the WMM is the slave system responsible for storing visual and/or spatial information

• Information is stored temporarily in the VSS

• The VSS has a limited capacity

• The VSS can be further divided into:

  • the visual cache: this component stores visual data e.g. colour, shape

  • the inner scribe: this component stores the arrangement of objects within the visual field of view

Episodic buffer

• The function of the episodic buffer (EB; added to the model in 2000) is to receive information from the CE, PL and VSS and to integrate this information into 'episodes'

  • The EB records information as episodes, so that it is time-sequenced

• Information is stored temporarily by the EB

• The EB is separate from LTM, but it forms an important stage in long-term episodic learning

• The capacity of the EB is limited

Evaluation

Strengths

• The case study of KF (Shallice & Warrington, 1970) offers support for the WMM

  • KF suffered a brain injury after which his STM was severely impaired

  • KF struggled to process verbal/auditory information but his ability to recall visual information was unaffected

    • This is evidence that there are different slave systems in the working memory which code for verbal/auditory information and visual information

• Dual-task performance effect (Baddeley, 1976) may provide evidence for the CE

  • Participants were asked to perform a digit span task (repeating a list of numbers) and a verbal reasoning task (answering true or false questions) at the same time

  • As the number of digits increased, participants took longer to answer the true/false questions (not significantly longer)

  • Baddeley concluded that the verbal reasoning task used the CE and the digit span task used the PL

Limitations

• There is a lack of detail on the role of the CE

  • This lack of detail may be due to the fact that the CE is very difficult to operationalise and measure

  • There may be more than one central component to the CE but to date, this has not been established with empirical evidence

• The dual-task performance effect relies on highly controlled lab conditions using tasks that are unrelated to real-life scenarios

  • This lack of 'realness' lowers the ecological validity of research in this field