Saturday, November 26, 2011

SECRETS OF MEMORY: Part I Three-store model of memory

Some people often complain that they have memory lapses. Some think even of memory loss! When tested their immediate, recent and remote memories prove normal. The best way to avoid anxiety about memory loss is learning the secrets of the cognitive processes involved in the mental faculty of memory.

Our immediate and distant past defines who we are, what we believe, what we can do, and what we feel. Just imagine what the life would be like if one loses all memory. Try to imagine what would be your situation if you have no recollection of where you were born, where you grew up, what you did in school, where you work, whom you live with, what you look like and even what you thought or did just moments ago. The loss of hearing, vision and other sensory modalities would be tragic indeed, but one would still possess a sense of identity so long as memory remained intact. The loss of memory would steal one’s very life and individuality.

How is it possible to remember what you were thinking five seconds ago, where you lived five years back or what you were doing five days ago? Intense interest in memory is not at all mysterious. The lives of individuals have meaning only because of memory.

The researches have revealed the complexities and secrets of our commonplace mental faculty known as memory. There has been evolved a three-store model of memory. (See the figure)

The first level of a hierarchical system of memory comprises three storage systems viz. sensory memory, short-term memory, and long-term memory. Each of these memory stores includes subcomponents which would be dealt with later.

Sensory memory refers to the brief persistence of the stimuli following sensation. When you see a flower its visual sensation will remain as such for a brief time. This is sensory memory. Its function is to permit stimulus to be perceived, recognized and entered into short-term memory. Without sensory memory, events in the environment would be forgotten as soon as they are registered in the nervous system. Thousands of sensations are experienced every  moment by the individual, but all sensory memories are not permitted to be perceived, recognized  and entered into short-term memory store.

All of us have experienced looking up a new telephone number in the directory and then repeating it silently until we reach for the telephone and dial the number successfully. Without silent repetition the new telephone number is easily lost if we wait too long to dial or are interrupted before dialing the number. The new phone number is available only temporarily in the short-term memory store. This experience with new telephone number is entirely different from that of the recall of our own telephone number. Unlike the fragile short-term memory of the new number our own number seems locked permanently in a long-term store of memory from which it can be retrieved with ease at any time.

Memory involves three basic processes viz. encoding, storage and retrieval. Encoding of memory concerns perceiving, recognizing and further processing of an object or event so that it can be remembered later. It is entirely possible that an event is forgotten because it was not well-encoded in the first place. Encoding must be followed by the successful storage of the event in long-term memory. An event may be encoded and held for a brief period of time in short-term memory. For it to be remembered over a long period of time it must be stored in long-term memory. The failure to transfer information from short-term memory to permanent storage in long term memory is another way memory can fail. In order to transfer new information to the long-term memory storage it has to be rehearsed or repeated many times. That is why in order to improve the leaning skill the student has to repeat new lessons many times as pointed out in the earlier post titled “How to improve your learning skill.”

Finally, retrieval concerns searching long-term memory and finding the event that has been encoded and stored. An event may be available if it is encoded properly and stored successfully in long-term memory. Yet if this event cannot be retrieved successfully, then it is inaccessible to consciousness.  

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