Baddeley and Hitch proposed that memory has 4 components. The central executive, phonological loop, visuospatial sketchpad and the episodic buffer. The central executive decides how to share out and direct attention to incoming information. The phonological loop can be thought of as a maintenance rehearsal mechanism for retaining verbal information. It is sub-divided into two other components, the phonological store (inner ear), which holds acoustically coded information, and the articulatory process (inner voice), which allows for sub vocal rehearsal (words you are about to say).
Furthermore, the visuospatial sketchpad (inner eye) is responsible for storing visual and spatial information. In other words, it codes information in images and can create and manipulate visual and spatial images. Finally, the episodic buffer. This component takes information from different sources and integrates them together. For example, Baddeley suggested if we imagine an elephant playing ice hockey, we have to draw out images stored in long term memory and combine them into a moving image.
The working memory model is good and is an improvement over the multi-store model. It demonstrates how the short term memory works because it explains how we can store information briefly and simultaneously manipulate it, for example, mental arithmetic. This shows that the model has face validity, which means that the test appears to measure what it is intended to. There is evidence to prove the existence of the phonological loop.
Baddeley thought that because longer chunks of information take longer to say, this may affect how much the short term memory can hold, rather than the capacity. This is known as the word length effect and it supports the existence of a phonological loop. However, there are also arguments to suggest weaknesses of the working memory model. The main limitation is the lack of clarity about the central executive. A psychologist argued that the central executive may be more than just one system, possibly consisting of more than one component.
This could make the working memory model appear reductionist because it has only been described as being unitary and over simplified. From this, it could be suggested that it is lacking in detail and is not fully reliable. Finally, much of the supporting evidence for this model was by one of the psychologists who proposed it (Baddeley). Here, assumptions could be made as to whether investigator effects play a part as Baddeley may want to prove his beliefs. This means that the supporting evidence many not always be fully reliable.