working memory model Flashcards
Baddeley and Hitch
The working memory model (WMM, Baddeley and Hitch 1974) is an explanation of how one aspect of memory (short-term memory) is organised and how it functions.
The WMM is concerned with the ‘mental space that is active when we are temporarily storing and manipulating information, for example when working on an arithmetic problem or playing chess or comprehending language, etc.
The model consists of four main components, each of which is qualitatively different especially in terms of coding and capacity.
central executive
The central executive (CE) has a supervisory role. It monitors incoming data, focuses and divides our limited attention and allocates subsystems to tasks (see below). The CE has a very limited processing capacity and does not store information.
first slave system-phonological loop
One of the subsystems is the phonological loop (PL). It deals with auditory information (i.e. coding is acoustic) and preserves the order in which the information arrives. The PL is subdivided into:
• The phonological store, which stores the words you hear.
• The articulatory process, which allows maintenance rehearsal (repeating sounds or words in a loop’ to keep them in working memory while they are needed). The capacity of this loop’ is believed to be two seconds worth of what you can say.
-You can keep in your phonological loop as much as you can say in about 2 seconds — by mentally repeating it over and over.
second slave system-visuo-spatial sketchpad
The second subsystem is the visuo-spatial sketchpad (VSS). The VSS stores visual and/or spatial information when required. For example, if you are asked to work out how many windows there are on your house you visualise it. It also has a limited capacity, which according to Baddeley (2003) is about three or four objects (see Apply it below). Robert Logie (1995) subdivided the VSS into:
• The visual cache, which stores visual data.
• The inner scribe, which records the arrangement of objects in the visual field.
third slave system-episodic buffer
The third subsystem is the episodic buffer (EB). This was added to the model by Baddeley in 2000. It is a temporary store for information, integrating the visual, spatial, and verbal information processed by other stores and maintaining a sense of time sequencing - basically recording events (episodes) that are happening. It can be seen as the storage component of the central executive and has a limited capacity of about four chunks (Baddeley 2012). The episodic buffer links working memory to long-term memory and wider cognitive processes such as perception.
strength-support from clinical evidence
One strength is support from Tim Shallice and Elizabeth
Warrington’s (1970) case study of patient KF (see also page 49).
After his brain injury, KF had poor STM ability for auditory (sound) information but could process visual information normally.
For instance his immediate recall of letters and digits was better when he read them (visual) than when they were read to him (acoustic). KF’s phonological loop was damaged but his visuo-spatial sketchpad was intact.
This finding strongly supports the existence of separate visual
and acoustic memory stores.
Counterpoint-However, it is unclear whether KF had other cognitive impairments (apart from damage to his phonological loop) which might have affected his performance on memory tasks. For example, his injury was caused by a motorcycle accident. The trauma involved may have affected his cognitive performance quite apart from any brain injury (how the crash affected him from stress or shock).
This challenges evidence that comes from clinical studies of people with brain injuries that may have affected many different systems.
strength-support from dual task studies
Another strength is that studies of dual-task performance support the separate existence of the visuo-spatial sketchpad.
When Baddeley et al’s (1975) participants carried out a visual and verbal task at the same time (dual task), their performance on each was similar to when they carried out the tasks separately. But when both tasks were visual (or both were verbal), performance on both declined substantially. This is because both visual tasks compete for the same subsystem (VSS), whereas there is no competition when performing a verbal and visual task together.
This shows there must be a separate subsystem (the VSS) that processes visual input (and one for verbal processing, the PL).
limitation-nature of the central executive
One limitation is that there is a lack of clarity over the nature of the central executive.
Baddeley (2003) himself recognised this when he said, ‘The central executive is the most important but the least understood component of working memory. The CE needs to be more clearly specified than just being simply ‘attention. For example, some psychologists believe the CE may consist of separate subcomponents.
This means that the CE is an unsatisfactory component and this challenges the integrity of the WMM.
