Atkinson and Shiffrin 1968 suggested that memory was comprised of three separate stores - the Sensory Memory store, the Short-term Memory store, and the Long-term Memory store.
Information from all around us enters the through the sensory memory and encoded through one of the 5 senses depending on the type of information. If attention is paid to this information it will enter short term memory which has a limited capacity of about 4 chunks of information Short term memory has a capacity of 7+/- 2 bits of information according to Miller. It can last up to 18 seconds without rehearsal according to Peterson and Peterson. Baddeley found that information in Short term memory is encoded mainly acoustically. If maintenance rehearsal takes place it will remain in Short term memory or be forgotten through decay or displacement. Elaborative rehearsal will then transfer information into long term memory) which has unlimited capacity. Baddeley found that LTM encodes mostly semantically. Information can be retrieved from Long term memory to be used in Short term memory when needed and can be forgotten through decay or displacement.
Most of the scientific evidence which supports the multi store memory model lacks validity because it is carried out in a laboratory, which is an artificial environment. The explanation of the multi store memory is too simple for a complex process because it explains little about Short term memory and Long term memory but merely describes them as fixed structures and does not take into account; an example of this is that there are different types of long term memory e.g. procedural or episodic.
The multi store memory suggest there is long term and short term memory each operate alone but evidence suggests this is not true, a short term memory case study by Shallice and Warrington 1970 studies KF who suffered brain damage he had difficulty with verbal information in short term memory