This essay has a total of 1872 words and 8 pages.


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
Continues for 4 more pages >>