CONSOLIDATION OF MEMORY
The process by which a
short-term memory is crystallized into a long-term memory is called memory
consolidation.
Consolidation causes permanent facilitation of synapses. It is possible by
rehearsal mechanism, i.e. rehearsal of same information again and again accelerates
and potentiates the degree of transfer of short-term memory into long-term
memory. This is what happens in memorizing a poem or a phrase.
CLASSIFICATION OF
MEMORY
Memory is
classified by different methods, on the basis of various factors.
Short-term Memories
and Long-term Memories
Generally,
memory is classified as short-term memory and long-term memory.
1. Short-term memory
Short-term memory is the
recalling events that happened very recently, i.e. within hours or days. It is
also known as recent
memory. For example, telephone number that is known today may be remembered
till tomorrow. But if it is not recalled repeatedly, it may be forgotten on the
third day. Short-term memory may be interrupted by many factors such as stress,
trauma, drug abuse, etc. There is another form of short-term memory called working
memory. Short-term
memory may be interrupted by many factors such
as stress, trauma, drug abuse, etc. There is
another form of short-term memory called working memory. It is concerned with
recollection of past experience for a very
short period, on the basis of
which an action is executed.
2. Long-term memory
Long-term memory is the recalling of
events of weeks, months, years or sometimes lifetime. It is otherwise called
the remote
memory. Examples are, recalling firstday of
schooling, birthday celebration of previous year, picnic
enjoyed last week, etc. Long-term memory is more
resistant and is not disrupted easily.
Explicit and Implicit
Memories
Physiologically,
memory is classified into two types, namely explicit memory and
implicit memory.
1. Explicit memory
Explicit
memory is defined as the memory that involves conscious recollection of
past experience. It consists of
memories regarding events, which occurred in the external
world around us. The information stored may be about
a particular event that happened at a particular time and
place. Explicit memory is otherwise known as declarative
memory or recognition memory. Examples
of explicit memory are recollection of a
birthday party celebrated three days ago, events taken
place while taking breakfast, etc.
Explicit memory involves
hippocampus and medial part of temporal lobe.
2. Implicit memory
Implicit
memory is defined as the memory in which past experience is utilized
without conscious awareness. It helps
to perform various skilled activities properly. Implicit
memory is otherwise known as non-declarative memory or skilled memory. Examples
of implicit memory are cycling, driving,
playing tennis, dancing,
typing, etc. Implicit memory involves the sensory and motor pathways.
Memories Depending
upon Duration
Depending
upon duration, memory is classified into
three
types:
1. Sensory memory
2. Primary memory
3. Secondary memory.
1. Sensory memory
Sensory memory is the ability
to retain sensory signals in sensory areas of brain, for a very short period of
few seconds after the actual sensory experience, i.e. few hundred milliseconds.
But, the signals are replaced by new sensory signals in less than 1 second. It
is the initial stage of memory. It resembles working memory.
2. Primary memory
Primary memory is the memory
of facts, words, numbers, letters or other information retained for few minutes
at a time. telephone number in the directory, we remember the number for a short while. After appreciating
beautiful scenery, the details of it could be
recalled for some time. Afterwards, it
disappears from the memory. Characteristic
feature of this type of memory is that the
information is available for recall easily from memory
store itself. One need not search or squeeze through
the mind, but this memory is easily replaced by
new bits of memory, i.e. by looking into another telephone
number, the first one may disappear.
3. Secondary memory
Secondary memory is the storage of
information in brain for a longer period. The information could
be recalled after hours, days, months
or years. It is also called fixed memory or permanent memory. It
resembles long-term memory.
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