Working memory model

• Baddeley and Hitch's working memory model (1974)

  • STM is made up of the central executive, phonological loop, visuo-spatial sketchpad and episodic buffer.
• Central executive - Described as an 'attentional process' with a very limited processing capacity. It allocates tasks to the 3 slave systems.
• Phonological loop - Auditory information. Allows maintenance rehearsal by being made up of the articulatory process (stores words you hear).
• Visuo-spatial sketchpad - Combines visual and spatial information processed by other stores, giving a 'complete picture' (eg- recalling a famous landmark). It is divided into the inner scribe (spatial and movement information) and visual cache (temporary storage of visual information). Capacity is around 4-5 chunks (Baddeley).
• Episodic buffer - Integrates all types of data processed by the other stores (eg - auditory, visual, spatial) and is described as the storage component of the central executive, and a crucial link to the STM and LTM.
• Strengths of the working memory model:

  • Supporting studies - Shallice and Warrington (1970) studies of KF provides support for the WMM because their findings show that KF had very poor STM recall for auditory / verbal stimuli, but increased STM recall for visual stimuli (selective impairment). This suggests that the components of memory which process auditory and visual stimuli are separate (as described in the WMM through the phonological loop and the visuo-spatial sketchpad).
• Strengths of the working memory model:

  • Supporting studies - Baddeley (1975) conducted dual task performance (2 visual tasks) where each participant tracked racking moving lights and described angles of letter F. This showed decreased performance. For one visual and one verbal, performance was better. This supports the idea that the central executive has a very limited processing capacity (as predicted by the WMM) and that the VSS and PL are separate.
• Strengths of the working memory model:

  • Neuroscanning evidence - Prabhakaran (2000) conducted fMRI scans and asked participants to complete tasks with equal spatial and verbal information. In another condition, both information types were done at the same time. There was more activation in prefrontal cortex when information was integrated, but more in posterior regions when not. This suggests the EB exists in prefrontal cortex which specialises in combination of temporary storage of visual and verbal/auditory information.
• Limitations of the working memory model:

  • Vague definitions - The central executive has not been precisely defined. For example, the term ‘process’ is vague, and the central executive may be made up of several sub-components or even be part of a larger component itself in working memory. This lack of a comprehensive explanation for each component of WMM draws doubts about the accuracy of its depiction of working memory.