The Working Memory Model

Baddeley and Hitch

Evidence supporting the WMM

Strengths and Weaknesses

Comparison with the MSM


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Baddeley and Hitch (1974)

Central Executive: directs attention to particular tasks and determines how 'resources' are allocated to tasks. Data arrives from the senses or LTM and it has a very limited capacity.

Visuo-spatial sketch pad (innner eye): visual and/or spatial information is temporarily stored here. visual = what things look like. spatial = relationship between things

Phonological Loop: deals with auditory information and preserves the order of information. It consists of two parts:-

  • Phonological Store (inner ear): holds words you hear
  • Articulatory Process (inner voice): used for words seen or heard

Episodic Buffer: an extra storage system that has limited capacity. It intergrates information from the central executive, phonological loop, visuo-spatial sketch pad and also from LTM.

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Evidence Supporting the WMM

Doing two tasks using the same or different components

Baddeley and Hitch

Gave participants two tasks to do simultaneously. T1 occupied central executive and T2 involved either articulatory loop or both the central executive and the articulatory loop, or no additional task.

T1 slower when given a task involving both the cnetral executive and articulatory loop. Speed on T1 was same whether using articulatory loop or no extra task.

Shows that doing two tasks that involve the same component causes difficulty. Also suggests when different components are used, performance is not affected.

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Evidence Supporting the WMM

Evidence for the central executive

Bunge et al (2000)

used fMRI to see which parts of the brain were most active when participants were doing two tasks.

The same brain areas were active in either dual or single task conditions but there was significantly more activation in the dual-task condition indicating that increased attention demands were reflected in brain activity.

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Evidence Supporting the WMM

Evidence for the phonological loop and articulatory process

The phonological loop explains why word length effect occurs.

Word length effect: people cope better with short words than long words in working memory (STM).

The phonological loop holds the amount of information that you can say in 2 seconds. This makes it hard to remember a list of long words compared to shorter words. The longer words can't be rehearsed on the phonological loop because they don't fit.

But the word-lenth effect disappears if a person is given an articulatory supression task. This repetitive task ties up the articulatory process and means you can't rehearse the shorter words more quickly than the longer ones, so the word-length effect disappears. This is evidence for the articulatory process.

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Evidence Supporting the WMM

Evidence for the visuo-spatial sketch pad

Baddeley et al

Participants were given a visual tracking task. At the same time they were given two other tasks. T1 was to describe all the angles on the letter F; T2 was to perform a verbal task.

T1 was very difficult but not T2, presumably because the second task involved two different components.

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Evidence Supporting the WMM

Evidence for the episodic buffer

Baddeley et al

found when participants were shown words and then asked for immediate recall, their performance was much better for sentences (realted words) than for unrelated words. This supports the idea of an immediate memory store for items that are neither visual nor phonological.

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Evidence Supporting the WMM

Evidence from brain-damaged patients


showed that STM works independantly of LTM, as he had no problem with long-term learning but some aspects of his immedaite memory were impaired.

His short-term forgetting of auditoy information were limited in respect of verbal material such as letter and digits but not meaningful sounds.

Thus his brain damage seemed to be restricted to the phonological loop.


Had generally good lerarning abilities with the exception of being unable to learn word pairs that were presented out loud. This suggests damage to the phonological loop.

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Strengths and Weaknesses of the WMM


  • model explains observations made by psychologists such as word-length effect experienced by individuals with brain damage such as KF and SC
  • considerable amount of research evidence to support model
  • WMM has continued the refinement by identifying further components of memory
  • Sternberg (2006) " the working memory model is probably the most widely used and accepted today


  • What exactly is the central executive? Some psychologists feel answer (allocates resources and essentially the same as 'attention') is too vague
  • notion of a single central executive is wrong and there are probably several components
  • Eslinger and Damasio (1985) studied EVR who had a cerebal tumor removed. Performed well on tests requiring reasoning which suggested central executive was intact. However, had poor decision making, suggests that in fact his central executive was not wholly intact
  • Some key evidence for WMM comes from case studies of individuals who have suffered brain damage, can't make 'before and after' comparisons so it is not clear whether changes in behaviour are caused by the brain damage
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Comparison with the MSM

  • offers a better account than the STM component of MSM
  • WMM includes verbal rehearsal as an optional process rather than the only mean by which information is kept in immediate memory
  • WMM emphasises process more than the MSM which emphasised structure
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  • Episodic buffer has storage space for acoustic and visual information
  • word-length effect shows limited capacity of phonological loop
  • Duel task: when the participants are asked to do two tasks at the same time
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