Memory is essential for everyday functioning and can be described as the retention of learning and experience. There are three stages of the way we process things into our memory: encoding, storage and retrieval. Encoding transform incoming information into a form that can be stored into memory. Storage holds the information in the memory until it is needed, where retrieval gets it out in order for it to be used.
According to the multi store model for memory, memory is divided into three sections, sensory, short term and long term. The function of sensory memory is retaining information long enough to decide whether or not it is worthy of further processing. Information in this memory is only stored for up to one or two seconds.
Information in the short term memory can be held visually, acoustically and semantically, there is evidence for this however the main encoding system for short term is acoustically. It has a very limited capacity of 7+-2 items of information however this number can be increased using the method of chunking, where you separate items into chunks, making it easier to remember. The digit span test measures the capacity of the short term memory and children who struggle to read and write usually score very low on digit span tests.
Information, when rehearsed, can be kept in the short term memory for more than 30 seconds when verbally recalling in the rehearsal loop. Items that are unrehearsed get forgotten through displacement. The duration of the short term memory was measured using the Brown-Peterson technique. Participants were given trigrams which they had to recall after varying amounts of time from 0-18 seconds. They had to then do an interference task to prevent the participants from rehearsing. Only 10% of the trigrams were recalled after 18 seconds, this being the new, average duration of the short term memory.
The long term memory differs from that of the short term as it has unlimited capacity. Atkinson and Shiffrin claimed that forgetting in the long term memory occurs due to confusion between similar long term memories and not being able to find the appropriate memory trace. Encoding in the long term memory appears to be semantic and the duration of long term memory is a lifetime.
The primacy and recency effect supports the multi store model for memory because it argues the fact that short term and long term memory are two separate stores in memory. In Murdock’s study, participants had to learn a list of words that varied in length from 10 to 30 words and free recall them, with each word being viewed for 2 seconds. The results were the words from the beginning of the list (primacy) and words from the end of the list (recency) were remembered. However the words in the middle (Asymptotes) were usually forgotten. Words early in the list were stored in long term memory because the person had time to rehearse the word and the words at the end of the list were still fresh in the short term memory so they were easily recalled. Asymptotes had been there too long to be in the short term memory however weren’t rehearsed enough to be stored in the long term memory, so they were discarded through displacement. Although this study supports the model as it shows that two separate stores are used in recalling the words, the study does lack ecological validity as it is not an everyday life experience to recall words.
The study of HM supports the model because it shows that the long term and short term memories are two distinct stores. After having his hippocampus accidently removed due to surgery for epilepsy, his short term memory remained intact. However after the accident, HM’s long term memory had been damaged as he was unable to form new memories. He couldn’t transfer new information into his long term memory. Despite being able to remember people he had known long ago, new people he had encountered were like strangers to him. There are specific deficits in which some abilities, such as learning new information are impaired whilst others like language are quite normal.
Evidence against the model is the idea of flashbulb memories. It contradicts the multi store model as information appears to have gotten into the long term memory without having to be rehearsed. Indeed in everyday life we rarely ever rehearse information yet we have little problem in storing huge amounts of it so this idea criticises the idea of rehearsal. Individuals can have significant occurrences happen to them in their lifetime that only happen once ad they will remember these memories without the need to rehearse them.
Many of the studies that were conducted in order to investigate the idea of the multi store model for memory were criticised for lacking in ecological validity. Many of the studies supporting the model used laboratory experiments, for example the study of Murdock on the primacy and recency effect and the study of the digit span capacity. They can therefore be criticised in terms of ecological validity and demand characteristics as it was evident that participants were being involved in an experiment so therefore could have guessed the aim and it was also artificial as it is not an everyday life occurrence to remember digits in that context. These experiments tell us very little on how memory works in real life.
The study of KF also criticises the model because KFs visual short term memory remained undamaged after brain damage due to a motorbike accident and KF could also store long term memories without them needing to pass through his damaged long term memory. This criticises the model in two ways: according to the multi store model, memories have to pass through the short term memory in order to be stored in the long term memory. KF’s verbal short term memory was damaged despite his visual memory being intact, suggesting that the short term memory isn’t a unitary store, with different parts dedicated to processing different types of information.
Korsakov’s syndrome supports the model as alcoholics may get Korsakov’s syndrome. They will forget all material and are unable to transfer information from their short term memories into their long term memories. This again supports the notion that the long term and short term memories are two separate stores because alcoholics with Korsakov’s syndrome need their short term memory in order to transfer information from it to their long term memory.
The model is also criticised for over simplifying the idea and concept of memory with its views on long term and short term memory structures operating in this single, unitary fashion and we now know that this isn’t the case. Cases like that of KF shows that the short term memory doesn’t work in a unitary fashion because he was able to make visual memories however his short term verbal memory was damaged. Rehearsal is important in some cases of making new memories however the multi store model emphasised too much on the rehearsal loop because in everyday life we rarely ever rehearse information yet we remember a lot of things.