Working memory model

Who proposed the theory? When?

Baddeley and Hitch, 1974

What is the central executive?

Essentially, an attentional process with a supervisory role - it focuses, divides and switches our limited attention. It is modality free and able to briefly process different forms of information (eg- visual, haptic, etc). It monitors incoming data, makes decisions and allocates slave subsystems to tasks. It has a very limited processing capacity and does not store information.

What is the phonological loop?

A slave subsystem that temporarily stores verbal information. It desks with auditory information sounds, so encoding is acoustic. It also preserves the order in which information arrives. It is subdivided into:

• The articulatory process: allows for maintenance rehearsal to keep information in the phonological store whilst needed. The capacity is approx 2 seconds worth of what you can say.

• The phonological store: stores auditory information

What is the visuospatial sketchpad?

A slave subsystem that can temporarily stores verbal information visual and/or spatial information when required. It has a limited capacity (about 3-4 objects) and subdivides into:

• The visual cache: briefly stores visual data including shape and form of objects (2D)

• The inner scribe: briefly records arrangement of objects in the visual field (3D)

What is the episodic buffer?

A temporary store that integrates the acoustic, visual and spatial information processed by other subsystems. It also maintains a sense of time sequencing, recording episodes that are happening. It had a limited capacity of about 4 chunks. It combines information from the other subsystems with long term memory and links to wider cognitive processes, such as perception.

Strength?

Evidence from case studies of brain damaged patients supports the idea of separate STM stores. Shallice and Warrington (1974) reported the case study of KF, who suffered STM impairment following a motorcycle accident. KF had a digit span of one, suggesting gross impairment in his phonological store, but his visual memory was in tact. This supports the proposal that working memory has two subsystems to desk with verbal and visuospatial information relatively independently.

Weakness?

There are problems in specifying the precise functioning of the central executive. Elsinger and Damasio (1985) describe the case study of a man with brain damage resulting from the removal of a brain tumour. His reasoning was good, his IQ was high and he coped well with interference during memory tasks - all of which suggest his central executive was functioning well. However, his decision making was very poor (eg- it took him hours to decide where to eat). This is a weakness of the model because if the central executive were a single system, we would expect all or none of these abilities to be affected, therefore this case study suggests the central executive is not a single system.