Memory Retention
The following are previous studies on memory retention. It contains a
definition and type of memory retention from different authors; also it contains
the characteristics of people who have high, average, and low memory
retention.
Cognitive psychologist identifies three common operations of memory
(.i.e. encoding, storage, and retrieval). Encoding refers to the transformation of
sensory information in to mental representation. In storage, we keep encoded
information in our memory and in retrieval; we simply pull out that information
stored in the memory (Sternberg, 2009 as cited by Etino, 2015). In fact as a
person reassesses their past experiences and utilizes that information to
present situation, they are using their memory.
In addition, Spring (2001) as cited by Tom Yin, (2013) whether it is a
child working on their homework, a college student studying for an exam, or an
adult working at their desk; they may find themselves listening to music while
stimulating their brain. It is then that the question arises of how the human
brain functions in the presence of music, and how music is able to affect
retention of memory. There are two major temporal classifications of memory:
long-term memory and working (or short-term) memory. Long-term memory
can last for days, weeks, or even years depending on the event and its
associations. Working memory lasts for a few minutes and is easily forgotten
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due to the limited capacity it has. The fundamental difference between longterm
and working memory is that protein synthesis is required for long-term
memory, and they are similar in the fact that repetition enhances all types of
memory.
However, there are some additional type of memory by Matthew
MacDonald (Pogue Press/O’Reilly, 2008) What we usually think of as
“memory” in day-to-day usage is actually long-term memory, but there are also
important short-term and sensory memory processes, which must be worked
through before a long-term memory can be established. On Matthew
MacDonald’s book “Your Brain: The Missing Manual” he elaborated
specifically the following types of memory:
Firstly, Sensory memory is the shortest-term element of memory. It is
the ability to retain impressions of sensory information after the original stimuli
have ended. It acts as a kind of buffer for stimuli received through the five
senses of sight, hearing, smell, taste and touch, which are retained accurately,
but very briefly. For example, the ability to look at something and remember
what it looked like with just a second of observation is an example of sensory
memory. The stimuli detected by our senses can be either
deliberately ignored, in which case they disappear almost instantaneously,
or perceived, in which case they enter our sensory memory. This does not
require any conscious attention and, indeed, is usually considered to be totally
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outside of conscious control. The brain is designed to only process information
that will be useful at a later date, and to allow the rest to pass by unnoted. As
information is perceived, it is therefore stored in sensory
memory automatically and unbidden. Unlike other types of memory, the
sensory memory cannot be prolonged via rehearsal. Sensory memory is an
ultra-short-term memory and decays or degrades very quickly, typically in the
region of 200 – 500 milliseconds (1/5 – 1/2 second) after the perception of an
item, and certainly less than a second (although echoic memory is now
thought to last a little longer, up to perhaps three or four seconds). Indeed, it
lasts for such a short time that it is often considered part of the process
of perception, but it nevertheless represents an essential step for storing
information in short-term memory.
Secondly, Short-term memory acts as a kind of “scratch-pad” for
temporary recall of the information which is being processed at any point in
time, and has been referred to as "the brain's Post-it note". It can be thought of
as the ability to remember and process information at the same time. It holds a
small amount of information (typically around 7 items or even less) in mind in
an active, readily-available state for a short period of time (typically from 10 to
15 seconds, or sometimes up to a minute).
Thirdly, long-term memory encodes information for
storage semantically (i.e. based on meaning and association). However, there
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is also some evidence that long-term memory does also encode to some
extent by sound. For example, when we cannot quite remember a word but it
is “on the tip of the tongue”, this is usually based on the sound of a word, not
its meaning. Physiologically, the establishment of long-term memory involves
a process of physical changes in the structure of neurons (or nerve cells) in
the brain, a process known as long-term potentiation, although there is still
much that is not completely understood about the process. At its simplest,
whenever something is learned, circuits of neurons in the brain, known
as neural networks, are created, altered or strengthened. Over the years,
several different types of long-term memory have been distinguished,
including explicit, declarative and procedural memory (with a further subdivision
of declarative into episodic and semantic memory) and retrospective
and prospective memory.
However, Long-term memory is often divided into two further main
types: explicit (or declarative) memory and implicit (or procedural) memory.
Declarative memory (“knowing what”) is memory of facts and events, and
refers to those memories that can be consciously recalled (or "declared"). It is
sometimes called explicit memory, since it consists of information that is
explicitly stored and retrieved, although it is more properly a subset of explicit
memory. Declarative memory can be further sub-divided into episodic
memory and semantic memory. Procedural memory (“knowing how”) is
the unconscious memory of skills and how to do things, particularly the use of
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objects or movements of the body, such as tying a shoelace, playing a guitar
or riding a bike. These memories are typically acquired through repetition and
practice, and are composed of automatic sensorimotor behaviors that are so
deeply embedded that we are no longer aware of them. Once learned, these
"body memories" allow us to carry out ordinary motor actions more or less
automatically. Procedural memory is sometimes referred to as implicit
memory, because previous experiences aid in the performance of a task
without explicit and conscious awareness of these previous experiences,
although it is more properly a subset of implicit memory.
Moreover, declarative memory can be further sub-divided into episodic
memory and semantic memory. Episodic memory represents our memory
of experiences and specific events in time in a serial form, from which we can
reconstruct the actual events that took place at any given point in our lives. It
is the memory of autobiographical events (times, places, associated emotions
and other contextual knowledge) that can be explicitly stated. Individuals tend
to see themselves as actors in these events, and the emotional charge and
the entire context surrounding an event is usually part of the memory, not just
the bare facts of the event itself. Semantic memory, on the other hand, is a
more structured record of facts, meanings, concepts and knowledge about the
external world that we have acquired. It refers to general factual knowledge,
shared with others and independent of personal experience and of the
spatial/temporal context in which it was acquired. Semantic memories may
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once have had a personal context, but now stand alone as simple knowledge.
It therefore includes such things as types of food, capital cities, social
customs, functions of objects, vocabulary, understanding of mathematics, etc.
Both episodic memory and semantic memory require a
similar encoding process. However, semantic memory mainly activates
the frontal and temporal cortexes, whereas episodic memory activity is
concentrated in the hippocampus, at least initially.
Lastly, an important alternative classification of long-term memory used
by some researchers is based on the temporal direction of the memories.
Retrospective memory is where the content to be remembered (people, words,
events, etc.,) is in the past, i.e. the recollection of past episodes. It includes the
semantic, episodic memory, autobiographical memory, and declarative
memory in general, although it can be either explicit or implicit. Prospective
memory is where the content is to be remembered in the future, and may be
defined as “remembering to remember” or remembering to perform an
intended action. It may be either event-based or time-based, often triggered by
a cue, such as going to the doctor (action) at 4pm (cue), or remembering to
post a letter (action) after seeing a mailbox (cue). Clearly, though,
retrospective and prospective memories are not entirely independent entities,
and certain aspects of retrospective memory are usually required for
prospective memory. Thus, there have been case studies where an impaired
retrospective memory has caused a definite impact on prospective memory.