Multi-Store Model of Memory

Atkinson and Shiffrin (1968) developed the Multi-Store Model of memory (MSM), which describes flow between three permanent storage systems of memory: the sensory register (SR), short-term memory (STM) and long-term memory (LTM).

The SR is where information from the senses is stored, but only for a duration of approximately half a second before it is forgotten. It is modality-specific, i.e. whichever sense is registered will match the way it is consequently held (for instance, a taste held as a taste).

However, if attended to, sensory information moves into the STM for temporary storage, which will be encoded visually (as an image), acoustically (as a sound) or, less often, semantically (through its meaning). STM is thought to have a capacity of 5-9 items and duration of approximately 30 seconds. This capacity can be increased through ‘chunking’ (converting a string of items into a number of larger ‘chunks’, e.g. number 343565787 to 343 565 787).

Rehearsing information via the rehearsal loop helps to retain information in the STM, and consolidate it to LTM, which is predominantly encoded semantically. Information can be stored and retrieved for up to any duration, and equally has a seemingly unlimited capacity.

Evaluation of the MSM

Strengths:

• There is a large base of research that supports the idea of distinct STM and LTM systems (e.g. brain-damaged case study patient KF’s STM was impaired following a motorcycle accident, but his LTM remained intact).
• It makes sense that memories in the LTM are encoded semantically – i.e. you might recall the general message put across in a political speech, rather than all of the words as they were heard.
• The MSM was a pioneering model of memory that inspired further research and consequently other influential models, such as the Working Memory Model.

Weaknesses:

• Some research into STM duration has low ecological validity, as the stimuli participants were asked to remember bear little resemblance to items learned in real life, e.g. Peterson and Peterson (1959) used nonsense trigrams such as ‘XQF’ to investigate STM duration.
• The model is arguably over-simplified, as evidence suggests that there are multiple short and long-term memory stores, e.g. ‘LTM’ can be split into Episodic, Procedural and Semantic memory.
• It does not make much sense to think of procedural memory (a type of LTM) as being encoded semantically, i.e. knowing how to ride a bike through its meaning.
• It is only assumed that LTM has an unlimited capacity, as research has been unable to measure this accurately.