To summarise the Multi Store Memory Model:
The Multi Store memory model is a structural model composing of 3 completely separate memory stores where information passes across in a linear way. The 3 stores are:
• The Sensory memory store
• The Short-term memory store
• The Long-term memory store
Each have their own unique characteristics. The Sensory Memory receives information from the environmental stimuli through sight, hearing, touch, taste and smell however this is usually ignored for the most part. If this information is given “Attention” then it begins to pass into the short-term memory store. The Short-term memory store has a capacity of 7 +/- 2 items and a duration of up to 18 seconds with information encoding being auditory. Information is prone to decay and forgetting or displacement if new information arrives. If rehearsed deep enough through elaborate or maintenance rehearsal, information then transfers over to the Long-term memory store which has unlimited duration and capacity and information is encoded semantically. Here information can be recalled through retrieval at a later stage once processed.

Evaluating the working memory model
The working memory model (Baddeley & Hitch, 1974)

Replaces the unitary short term memory concept of the multi-store model

Separate processing resources for auditory and visual short term memory

Explains the memory deficit caused by KF\'s brain damage

The working memory model has many strengths over the multi-store model. It describes short term memory as a collection of active processing mechanisms that work in two modalities (verbal and visual) rather than a single store that simply rehearses verbal information. This allows it to explain memory function in patients with impairments to one component of working memory but with normal function in the other components, such as KF.

There is considerable research evidence for the existence of the individual components of working memory (see section above).

The major weakness of the working memory model is the central executive which, ironically, is its most important component. There is relatively little research evidence for its existence and it is by its nature very hard to directly investigate, although some recent research into patients with Alzheimer’s disease (e.g. Baddeley et al, 1991) has identified how an impaired central executive may affect memory function. The problem with researching the central executive is that it cannot itself be measured directly, and instead its function has to be inferred from performance at verbal and visual tasks. When we want to measure the functioning of a component we give it a task designed to reduce its performance, such as occupying the phonological loop with an articulatory suppression task.
If participants are able to perform the task then researchers conclude that the central executive is working properly, but if they perform the task poorly then they conclude that the phonological loop is impaired. In other words it is impossible to design a task that effectively tests the central executive without also affecting its slave systems, and so the central executive may never be adequately investigated and it will always remain a concept with limited support - Richardson (1984) calls this the circular argument.