Another element to the slave systems is the visuo-spatial sketchpad. This is used when you have to plan a spatial class like getting to one room to another. Visual information (what things look like) and spatial information (relationship between things) are temporarily stored here.
The final element to the three slave systems is the episodic buffer, added by Baddeley (2000) as he realised that the model needed a general store, because the visuo-spatial sketchpad and the phonological loop deal with processing and temporary storage. The central executive also has no storage capacity. However the episodic buffer is an extra storage system in which information from the central executive, the phonological loop, the visuo-spatial sketchpad and also the LTM is integrated.
There is a considerable amount of supporting evidence for the W.M.M. Especially for the four components it is made up of. Bunge et al. (2000) used FMRI to see which parts of the brain were most active when participants were performing two tasks (dual-task) as this should cause an increase in the activity of the central executive. They found that although the same areas of the brain were active in either a dual or single task condition, there was significantly more action in the dual-task indicating that increased attentional demands were reflected in brain activity. The phonological loop is a vital explanation as to why the word-length effect occurs as it seems that the phonological loop holds the amount of information that you can say in 2 seconds. This makes it harder to remember a list of long words compared to shorter words. Longer words cannot be rehearsed on the phonological loop because they don’t fit. However if a person is given an articulatory suppression task, this 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.
Baddeley et at. (1975b) demonstrated the existence of the visuo-spatial sketchpad. Participants were given a visual tracking task. At the same time they were given another task in which they had to describe the angles on the letter F (task 1) or they had to perform a verbal task (task 2). Task 1 proved more difficult to perform than task 2 presumably because the second task involved two different components. This is evidence to support the evidence related to the effects of doing two tasks using the same or different components.
Baddeley et al. (1987) also found that when participants were shown words and then asked for immediate recall, their performance was considerably better for related words than for unrelated words. This supports the idea for an immediate memory store for items that are neither visual nor phonological and that draw on LTM.
Studies from brain damaged patients also work in supporting the W.M.M. For example the case study of KF (Shallice and Warrington, 1970) showed that STM works independently of LTM as KF had no problems with long term learning but some aspects of his immediate memory were impaired. His short-term forgetting of auditory information was much greater than that of visual stimuli, and his auditory problems were limited in respect of verbal material like letters and digits. Therefore his brain damage seemed to be restricted to the phonological loop.
However although this case study works to support the W.M.M there is evidence from brain damaged patients which shows that there are limitations in the model. There are a number of problems with using evidence from brain damaged patients. Firstly, you cannot make before and after comparisons, so it is difficult to determine whether changes in behaviour are caused by the damage. Secondly, the process of brain injury is traumatic, which may itself change behaviour.
Another concern with the W.M.M is about the central executive. Its job is to allocate resources which is essentially the same as ‘attention’. This would imply that the central executive is too vague and does not really explain anything. Critics also feel that the notion of a single central executive is wrong and that there are probably several components. The study of EVR (Eslinger and Damasio, 1985) showed that despite the removal of a cerebral tumour he performed well on tests requiring reasoning suggesting his central executive was intact. However he did have poor decision- making skills. This suggests that his central executive was not wholly intact. Therefore we can see that central executive is unsatisfactory because it fails to explain anything and it is probably more complex than currently represented.
The W.M.M represents a shift in our understanding of memory as one activity, to be able to distinguish an array of different kinds of memory. The MSM offered a first step in the right direction in identifying the sub-components of memory and linking these with areas of the brain. However the W.M.M has continued the refinement by identifying further components of memory. This suggests that the W.M.M has been influential in providing a further understanding of how the memory works.
Another strength of the W.M.M is the fact that it offers a better account of STM than in the MSM. This is because it moves from describing immediate as a unitary store to one with a number of components. In comparison with the MSM, the W.M.M includes verbal rehearsal as an optional process rather than the only means by which information is kept in immediate memory. The W.M.M also emphasises process more than the MSM, which emphasised structure. The W.M.M suggests that immediate memory holds the most recently activated portion of LTM, rather than portraying STM as a way station on the way to and from LTM. Working memory moves the activated elements in and out of brief, temporary storage.
by
amyvanschalkwyk (student)
