Human Memory
Lesson 1
Human Memory Models Multi Store Model
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Key Terms Sensory Memory • A set of limited capacity, modality-specific stores that hold information for a very brief period of time.
STM • A temporary store where small amounts of information can be kept for brief periods. It is a fragile store and information can be lost.
Key Terms LTM • A permanent store where limitless amounts of information ca be stored for long periods of time.
Encoding • The way in which information is represented in the memory store, e.g. by sound, meaning or image.
Key Terms Capacity • The amount of information that can be held in memory at any one time.
Duration • The length of time that memories can be held.
Stimulus Input
Multi-store Model Rehearsal
Sensory Memory
Attention
STM
Storage
Retrieval
LTM
Sensory Memory Fo rg ott
STM
en
Fo rg ott
LTM
en
Fo rg ot t en
Sensory Memory
• visual, auditory, haptic coding • limited capacity • very brief duration
STM
• mainly acoustic coding • limited capacity • brief duration
LTM
• mainly semantic coding • unlimited capacity • unlimited duration
• Many memory theorists have proposed that the memory store is divided into three stores (sensory, STM & LTM). • Atkinson & Shiffrin (1968) proposed a typical model of this type and their model arose from the information processing approach, an approach where memory is characterised as a flow of information through a system. • The systems is divided into a set of stages and information passes through each stage in a fixed sequence.
• There are coding, capacity and duration limitations at each stage, and transfer between stages may require recoding. • Atkinson & Shiffrin proposed that external stimuli from the environment first enter the sensory memory where they can be registered for very brief periods of time before decaying or being passed to STM. • STM contains only small amounts of information that is actually in active use at any one time.
• Material that is rehearsed in STM is passed onto LTM where it can remain for a lifetime. • Although loss is possible from this store through decay or interference.
Encoding in Sensory Memory • Coding in Sensory Memory is said to be visual, auditory and haptic coding (time in space).
Encoding in STM • Coding in STM is mainly acoustic however it can be visual.
Encoding in LTM • Coding in the LTM is assumed to be in terms of meaning which we could say is semantic. • Atkinson & Shiffrin also proposed various strategies used by individuals to manipulate the information flowing through the system. • One of the most important of these is rehearsal that allows information to be recycled within the STM and passed on into LTM.
Capacity • Capacity in Sensory Memory is very limited. • Capacity in STM is limited. • Capacity in LTM is unlimited.
Duration • Duration in Sensory Memory is very brief. • Duration in STM is brief. • Duration in LTM is unlimited.
Evaluation of the Multi Store Model • The multi-store model has stimulated a lot of research but is too simplistic to explain the whole memory system. • Crucial aspect of the multi-store model is that it makes a distinction between STM & LTM, which suggests that these two stores operate differently in terms of capacity, duration and encoding. • Evidence in support of this distinction can be made from case studies of people with brain damage that causes brain impairment. (See case study of H.M. that supports the above argument)
Case study of H.M. that supports the argument of a distinction between STM & LTM • Milner (1966) reported on a young man referred to as H.M., who was left with severe memory impairment after brain surgery. • He was able to talk normally and to recall accurately events and people from his life before surgery. • His immediate digit span was within normal limits.
• However, he was unable to retain any new information and could not lay down any new memories in LTM. • When told the death of his favourite uncle, he acted with considerable distress. • Later he frequently asked about his uncle and on each occasion reacted again with the same level of grief appropriate to hearing the news for the first time. • Cases such as these and Clive Wearing lend support to the multi-store model by pointing a clear distinction between LTM & STM.
• Back to the evaluation: There are some problems with this model. It is too simple and inflexible and does not take into account the strategies people employ to remember things. • The emphasis of this model is on the amount of information rather than its nature. • Some things are much more easier to remember than others, perhaps because they are more interesting, more distinctive, funnier and this model (the multi-store model) cannot account for these possibilities.
• The suggestion that rote rehearsal is the only means of transfer from the STM into LTM has also been criticised in alternative models such as the ‘levels of processing approach’. • Similarly the ‘working memory model’ of Baddeley and Hitch (1974) casts doubt on the assumption of Atkinson & Shiffrin that the STM is a unitary store with severely limited capacity. • Evidence for separate stores that support Atkinson and Shiffrin’s multi store model of memory.
• In the multi-store model the STM and LTM are viewed as separate and distinct stores. • Glanzer & Cunitz (1966) conducted the following experiment to see if they could find evidence for these separate stores. • Participants were presented with a list of words one at a time. They were then asked to recall the words and could do so in any order (this is referred to free recall). • Half of the participants recalled the words immediately after they had memorized them (immediate recall condition).
• The other half of the participants counted backwards for 30 seconds before they recalled the words (recall after distracter task).
Primacy and Recency • The superior recall of words at the beginning is called primacy effect, and the superior recall of words at the end is called recency effect. • The primacy effect occurs because the items at the beginning of the list presumably have been rehearsed and transferred to LTM from where they are recalled. • The recency effect presumably occurs because items are currently in STM are recalled from there.