The Multi-Store Model of Memory Flashcards
Key terms:
Multi-store model (MSM) = A representation of how memory works in terms of 3 stores called sensory register, short-term memory (STM) the long-term memory (LTM). It also describes how information is transferred from one store to another, how it is remembered and how it is forgotten.
Sensory register = The memory stores for each of our 5 senses, such as vision (iconic store) and hearing (echoic store). Coding in the iconic sensory register is visual and in the economic sensory register it is acoustic. The capacity of sensory registers is huge (millions of receptors) and information last for a very short time (less than half a second).
Atkinson & Shiffrin’s (1968, 1971) multi-store model (MSM) describes how info flows through the memory system. The model suggests that memory is made up of 3 stores linked by processing:
Sensory register
Stimulus from the environment; for example, the sound of someone’s name, I will pass on to the sensory registers along with lots of other sites, sounds, smells and so on. So this part of memory is not one store but several, in fact one for each of our five senses. The 2 main stores are called iconic memory (visual information is coded officially) and echoic memory (sounds – or auditory – information is coded acoustically). Material in sensory registers lasts only very briefly – the duration is less than half a second. The sensory registers have a high capacity, for example over 100 million cells in one eye, each storing data. Very little of what goes into the sensory register passes further into the memory system. But it will if you pay attention to it. So the key process is attention.
Short-term memory (STM)
STM is what is known as a limited capacity store, because it can only contain a certain number of’ things’ before forgetting it takes place. Previously we noted that the capacity of STM is, on average, somewhere between 5-9 items of information, the research suggests it might be more like 5 rather than 9. Information in STM is coded acoustically and lasts about 30 seconds unless it is rehearsed. Maintenance rehearsal occurs when we repeat (rehearse) material to ourselves over and over again. We can keep the information in our STM as long as we rehearse it. If we rehearse it long enough, it passes into long-term memory (LTM).
Long-term memory (LTM)
This is the potentially permanent memory store for information that has been rehearsed for a prolonged time. Psychologists believe that its capacity is unlimited and to last very many years. For example, Bahrick et al. (1975) found that many of the participants were able to recognise the names and faces of the school classmates almost 50 years after graduating (as mentioned in previous deck). We also saw the LTMs tend to be coded semantically (i.e. in terms of meaning). Although this material is stored in LTM, when we want to record it, it has to be transferred back into STM by a process called retrieval. According to the MSM, this is true of all our memories. None of them are recalled directly from the LTM.
Evaluation of the MSM
+ It is supported by research studies that show that STM and LTM are indeed qualitatively different. For example, Baddeley (previous deck) found that we tend to mix up words that sound similar one we are using our STMs. But we mix up words that have similar meanings when we use our LTMs. The strength of this study is that it clearly shows that coding in STM is acoustic and in LTM it’s semantic. So they are different, which supports the MSM’s view that these 2 memory stores are separate and independent. Further support is given by all the studies of coding, capacity and duration we encountered in the previous deck.
- The MSM states the STM is a unitary store, in other words there is only one type of short-term memory. However, evidence from people suffering from a critical condition called amnesia shows that this cannot be true. For example, Shallice & Warrington (1970) studied a patient with amnesia known as KF. They found that KS short-term memory for digits was very poor when they read them out loud to him. But his recall was much better when he was able to read the digits to himself. Further studies of KF another people with amnesia showed that there could even be another short-term store for non-verbal sounds (such as noises). The unitary STM is a limitation of the MSM because research shows that at the very least there must be one short-term memory store to process visual information and another one to process auditory information. The working memory model (later deck) includes these separate stores.
^ - Another case study, like the one above, that is an argument separate types of STM, is the case of HM. He underwent brain surgery to relieve his epilepsy in which unfortunately the hippocampus was removed from both sides of the brain (which we now know to be central to memory) because the procedure used was in its infancy and not fully understood. When his memory assessed in 1955, he thought the year was 1953, and that he was 27 (he was 31). He had very little recall of the operation and he couldn’t remember speaking with someone just an hour earlier. His LTM was tested over and over again but never improved with practice. He would read the same magazine repeatedly without remembering it. He couldn’t recall what he had eaten earlier in the same day. However, despite all this, he performed well on tests of immediate memory span, a measure of STM.
- According to the MSM, what matters of rehearsal is the amount of it that you do. So the more you rehearse some information, the more likely you are to transfer it to the LTM and remember for a long time. However, Craik & Watkins (1973) found that this prediction is wrong. What really matters about rehearsal is the type. They discovered that there are 2 types of rehearsal. Maintenance rehearsal is the type described in the MSM, but this does not transfer information into LTM, it just maintains it in STM. Elaborative rehearsal is needed for long-term storage. This occurs when you link the information to your existing knowledge, or you think about what it means. This is a very serious limitation of the LSM because it is another research finding that cannot be explained by the model.
