The multi-store model of memory: sensory register, short-term memory and long-term memory. Features of each store: coding, capacity and duration.
Atkinson and Shiffrin (1968) argued that there are three memory stores:
- Sensory store
- Short-term store
- Long-term store
Atkinson and Shiffrin’s (1968) multi-store model of memory (MSM) makes a distinction between the separate stores of sensory, short-term and long-term memory.
Main features include:
- It is a structural model
- STM and LTM are unitary stores
- Information passes from store to store in a linear way
- Rehearsal is needed to pass information from STM to LTM
- Each store has its own characteristics in terms of encoding, capacity and duration
- Explanations of forgetting are different for each store
Memory: The mental process used to encode, store and retrieve information.
Encoding: Encoding involves changing the information presented into a different form. Since words or other items in the short term store are rehearsed or repeated, we might assume that they are encoded in terms of their sound (acoustic coding). In contrast, the information we have stored in the long term memory nearly always seems to be stored in terms of its meaning (semantic coding). Encoding takes many different forms; visual, auditory, semantic, taste and smell.
Capacity: The short term store has very limited capacity, about 7 items. In contrast the capacity of the long term memory is assumed to be so large that it cannot be filled, it is said to have unlimited capacity and lasts potentially forever. Capacity in STM is 7±2 (Miller, 1956)
Duration: Information lasts longer in the long term store than in the short term store,. There is evidence that in the short term store, if not rehearsed, information will disappear within about 18 – 20 seconds and in contrast there is evidence that elderly people can recognise the names of fellow students from 48 years previously.
Storage: As a result of encoding, the information is stored in the memory system; it can remain stored for a very long time maybe a entire lifetime.
Retrieval: Recovering information from the memory system. Can be known as recall or remembering.
- Case Study Support: Case studies of brain damaged patients lend support to the multi-store model; they support the view that there are two different memory stores. For example Clive Wearing had part of his hippocampus destroyed by a virus in 1985 and is unable to commit anything new to long-term memory (yet retains long-term memories from before the virus; especially procedural skills, such as playing the piano). He has retained his short-term memory. This shows that short-term and long-term memory must be distinct, and that information travels from one to the other.
- Research Support: There is evidence that encoding is different in short term and long-term memory. For example Baddeley found that acoustic or sound encoding was in the short-term memory and semantic (by meaning) encoding was in the long-term memory. This supports the idea of distinct long-term and short-term stores.
- Research Support: There are huge differences in the duration of information in the short term and long term memory. Unrehearsed information in the short-term memory had vanished after about 20 seconds (Peterson & Peterson). In contrast some information in the long-term memory is still there 48 years after learning (Bahrick et al.) This supports the idea of distinct long-term and short-term stores.
- Overemphasis on rehearsal: The model argues that the transfer of information for short term to long-term memory is through rehearsal. However in daily life people devote little time to active rehearsal, although they are constantly storing new information into the long-term memory (smells, for example, cannot be rehearsed, yet are often retained in long-term memory). Rehearsal may describe what happens in laboratories but is not true to real life. Craik & Lockhart suggest that it is the level at which we process information that determines how well we remember it. Rehearsal represents a fairly shallow processing level.
- Oversimplification: This model is oversimplified. It assumes that there is a single short-term store and a single long-term store. These assumptions have been disproved, by evidence such as that from the studies of brain damaged patients. KF had a motorcycle accident that left him with a severely impaired verbal STM but he was still able to process visual and spatial information in his STM, showing that STM cannot be just one unitary store.
Video explaining what research has shown about the differences between STM and LTM