The Working Memory Model

The working memory model

• Baddeley and Hitch (1974) explained how one aspect of memory (STM) is organised and how it functions. It is concerned with the 'mental space' that is active when we are temporarily storing and manipulating information, e.g. when working on an arithmetic problem. It consists of four main components, each of which is different from each other in terms of coding and capacity

Central executive

• This has a 'supervisory' role. It monitors incoming data, focuses and divides our limited attention, and allocates subsystems to tasks. It has a very limited processing capacity and does not store information

Phonological loop

• One of the subsystems. It deals with auditory information (i.e. coding is acoustic) and preserves the order in which the information arrives

• Articulatory process

• Phonological store

Phonological loop: Phonological store

• This stores the words you hear

Phonological loop: Articulatory process

• This 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

Visuo-spatial sketchpad

• One of the subsystems. It stores visual and/or spatial information when required, e.g. 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

• Visual cache

• Inner scribe

Visuo-spatial sketchpad: Visual cache

• This stores visual data

Visuo-spatial sketchpad: Inner scribe

• This records the arrangement of objects in the visual field

Episodic buffer

• One of the subsystems. Added to the model by Baddeley in 2000. It is a temporary store of information, integrating the visual, spatial, and verbal information processed by other stores and maintaining a sense of time sequencing (recording events that are happening). Can be seen as the storage component of the central executive and has a limited capacity of about four chunks (Baddeley 2012). It links working memory to long-term memory and wider cognitive processes such as perception

Evaluation: Strengths

• Support from Shallice and Warrington's (1970) case study of patient KF. After his brain injury, KF had poor STM ability for auditory information but could process visual information normally, i.e. his immediate recall of letters and digits was better when he read them than when they were read to him. KF's phonological loop was damaged but his visual-spatial sketchpad was intact

• This strongly supports the existence of separate visual and acoustic memory stores

Evaluation: Strengths

• Studies of dual-task performance support the separate existence of the visual-spatial sketchpad.

• Baddeley et al's (1975) participants carried out a visual and verbal task at the same time, their performance on each was similar to when they carried out the tasks separately. But when both tasks were visual (or verbal), performance on both declined because both visual (or verbal) tasks compete for the same subsystem, whereas there is no competition when performing a verbal and visual task together

• This shows there must be a separate subsystem (VSS) that processes visual input (and one for verbal processing, the PL)

• External validity - tasks in the studies are artificial and do not replicate real life. This limits the WMM.

Evaluation: Weaknesses

• Lack of clarity over the nature of the central executive. Baddeley (2003) 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 rather than just being simply 'attention', e.g. some believe the CE may consist of separate subcomponents

• This means the CE is an unsatisfactory component and this challenges the integrity of the WMM