Discuss the need for an explanation of human memory, which proposes that memory is a set of stages, rather than a single process.This essay is going to discuss the need for an explanation of human memory, which proposes that memory is a set of stages rather than a single process. Flanagan (1997) defines memory as “ the mental function of retaining data, the storage system holding the data, and the data which is retained.” It is evident from reviewing the literature that an explanation of memory as a set of stages proves to be more understandable than as a single process, the theories of memory all providing information about how memory is structured and organised and the findings from the research studies inevitably pointing in the direction of memory existing as a set of stages rather than a single process. Therefore these are the areas which are to be outlined in this essay in order to understand the need to explain human memory as a set of stages.The nature of memory can be explained as a set of stages that are necessary but not sufficient for memory to have taken place.
These involve “input” -registering or encoding information, where a memory trace is formed from translating the sensory data, “storage” which is either temporary or permanent and “output” which involves retrieval – memories would be useless unless they could be retrieved. It is these stages that form the fundamental characteristics of the process of memory and in order for this to occur it is necessary for the data to become engaged in the memory structure. Memory structure can be separated into three distinct categories, sensory memory (input store) where the sensory data remains unchanged in the mind for a brief time but is rapidly lost through decay; short -term memory- which has a relatively limited capacity (approximately seven items) with rapid decay being prevented through rehearsal and finally long-term memory which is a relatively permanent storage system with an apparent unlimited capacity with information being held in enactive, iconic or symbolic form. The evidence for separate stores comes from empirical studies of duration, capacity, coding differences, serial position effect, brain damage and forgetting.In regard to duration there have been several studies that indicate separate stages, Sperling (1960) briefly showed participants a display of twelve letters organised in three rows and asked them to immediately recall the letters. It was found that if a tone was presented after the display signalling which row to report “recall was three times better demonstrating that available information disappears very rapidly”. This study demonstrates the existence of a sensory memory system where the information is lost through decay.
Peterson and Peterson (1959) found that delayed recall of trigams reduces performance from 80% after 3 seconds to 10% after 18 seconds, this is significant in that participants were given a task before recall in order to prevent rehearsal which supports the idea of the short term memory system wherein sensory data is lost rapidly without the involvement of rehearsal. Finally in a follow up study Atkinson and Shiffrin (1971) reported a longer duration of 15-30 seconds suggesting an upper limit for short term memory of 30 seconds, this suggests that any data to be stored for longer than this time would be inevitably stored in the long term memory where the duration time is potentially unlimited- demonstrated by forgetting.Secondly, further evidence for separate stores comes in the area of capacity. The above studies indicate that in terms of duration sensory memory is limited whereas the long-term memory store is potentially unlimited. Miller (1956) suggested that chunks limit the span of the short term memory not bits of information. This could explain why many categories consist of seven items e.
g. days of the week, wonders of the world and even telephone numbers. However, Simon (1974) found that there is a limit to chunk size with participants having a shorter memory span for larger chunks.
Miller’s (1956) study provides evidence for the long term memory as chunking relies on this memory structure in order to determine meaningfulness. Bower and Springston (1970) showed that participants recalled meaningful chunks better than meaningless groups.Coding differences also demonstrate the existence of different memory stores; i.e. short term memory is associated with acoustic coding whereas long term memory is associated with semantic coding. Baddeley (1966) showed that short term memory recall was poorer when word lists were acoustically similar whereas long term memory recall was worse when words were semantically similar and Conrad (1964) demonstrated that visually presented letters suffer from acoustic errors in immediate recall therefore they must be acoustically coded in the short term memory.
Therefore differences in coding demonstrate separate memory structures in particular the short term and long term. Glanzer and Cunitz (1966) demonstrated the serial position effect, participants were asked to recall word lists, if this was done immediately there was a primacy and recency effect with both the short term and long term memory being involved. It was found that if there was a delay of ten seconds or more there was only a primacy effect – with the long term memory only being effected. This is relevant in that it shows the difference in long and short term memory; with primacy being due to the fact that the first items are more likely to have entered the long term memory and recency occurs because the last items in the list are still in the short term memory.The final area to be discussed in terms of empirical studies that provide evidence for separate stores is forgetting.
Forgetting assumes that information that was stored in the short term or long term memory is now not available or is not accessible. It is in terms of availability and accessibility that the importance of forgetting, with regard to demonstrating separate stages in memory is to be approached. Failures of availability and accessibility include encoding failure occurs when data is not stored in the short or long term memory. Trace decay involves the physical form of memory disappearing with time due to neural decay; it explains sensory memory, short term memory forgetting and the effect of rehearsal. In regard to the long term memory, some kinds of memory do not decay e.
g. how to drive or ride a bike whereas others do not decay but become inaccessible e.g. the success of recall under hypnosis, electrical stimulation of the brain or the effectiveness of cues.
Displacement is another form of forgetting which applies only to the short term memory. According to research the short term memory is limited in capacity and therefore any excess information would be overwritten (displaced), Shallice (1967) found that the speed of presentation of digits affected recall less than the number of items which suggests that displacement must have caused the effect. This does not happen in the long term memory as it has a potentially unlimited capacity. Other failures of availability include interference – where one set of information competes with another causing it to be overwritten or completely lost e.g. McGeoch and McDonald (1931) with the findings being similar to the studies of trace decay. Studies of the effects of brain damage in terms of memory failure highlight the way memory works at a neurophysiological level.
Retrograde amnesia affects the short term memory because events immediately prior to the trauma are permanently forgotten presumably because information is lost from the short term memory at the time of the trauma (lack of consolidation). Whereas anterograde amnesia affects the long term memory structure, permanent memories remain intact but sufferers only remember new information for no longer than the normal short term memory span (i.e. 30 seconds) e.g. Baddeley (1990) case of Clive Wearing.
The evidence described above suggests three quite distinct stores, the theories of memory all provide information about how memory is structured and organised, e.g. Atkinson and Shiffrin (1968)- the multistore model, based on empirical evidence and from which many subsequent theories were derived e.g. the working memory model, Baddeley and Hitch (1974). In most cases in association with the research studies.
Therefore in regard to the question being addressed the need for memory to be explained in terms of a set of stages rather than a single process stems from the evidence provided from the empirical studies. It is apparent from these studies that there are three quite separate stores, this can not be disputed, however there are certain areas in the research that do not appear to be fully explained. For example, is it totally possible that the long term memory has an unlimited capacity, surely the information which is not readily accessible or available simply has not been stored in the first place and therefore this discredits trace decay and many forgetting studies, which in turn may discredit evidence for supporting the existence of memory as separate stages. Also in discussing the need for memory to be described as a set of stages rather than a single process, it is not necessary to concentrate on the particular theories which have been derived from the evidence available. This is relevant because the theories do not actually prove that memory is not a single process but are instead presenting a possible explanation of how the memory system operates based upon the available findings. However, the research that followed some of the theories does provide further explanation in order to make sense of the experimental data from previous studies.
Tulving (1972) further modified the divisions of the long term memory i.e. the procedural system into episodic and semantic learning and allowed a deeper understanding of the effects of brain damage – why particular types of memories are recalled and others are forgotten.
The working memory model Baddelely and Hitch (1974) suggested a working memory in place of the short term memory store and subsequent research found that “articulatory suppression did not affect decisions involving acoustic differences and therefore there must be a separate store for this”(Baddeley and Lewis 1981). Therefore although the theories may be valuable in attempting to describe the memory process, it is the research based upon the theories that give a greater understanding for the need for an explanation based on stages.In conclusion, the question posed was to “discuss the need for an explanation of human memory, which proposes that memory is a set of stages, rather than a single process”. When trying to discuss this need it became apparent that the fact that memory is not a concrete article made it all the more important that it was explained as a set of stages. This may be because as a set of stages, the complex structure of memory is all the more understandable and the theories of memory put together a “story” of how the memory process may work. However, most if not all theories or models describe rather than explain the memory process (providing a guideline) therefore the empirical evidence is really the only key in explaining why memory is a set of stages rather than a single process and it is from these that the ” need ” is derived.Bibliography: