Memory, like sweatshirts, comes in three sizes. There is a sensory storage system which can hold information for only a very brief time period. Next is a short-term storage which can hold a small amount of information. Finally, you have a long-term storage system which holds vast amounts of information.

What psychological processes are involved in remembering a stimulus which is briefly perceived, such as the license number of a car? Psychologists have discovered that a stimulus is maintained in a sensory storage system which holds information for less than a second. The sensory storage system is called iconic memory if visual stimuli are involved or echoic memory if the stimulation is auditory. Your sensory storage system appears to operate in a fairly automatic way.

Verbal Memory
Long term memory – Short term memory Source:


There seems to be no voluntary action you can take to prolong the life of information from sensory storage without using the next stage of memory, called short-term memory (STM), or primary memory. Information can be recycled in short-term memory by a process called rehearsal. When rehearsal is prevented or disrupted, information in short-term memory is lost and so cannot enter long-term memory (LTM).

However, once information has entered long-term memory, rehearsal is no longer necessary to guarantee that information is not forgotten. While preventing items from being forgotten is the major difficulty in short-term memory, long-term memory suffers from the opposite problem. There is so much information contained in long-term memory that locating and retrieving this information can be quite difficult.

Retrieval – Long Term Memory – Short Term Memory


Indeed, psychologists distinguish between information which is available in long-term memory and that which is accessible. All information in long-term memory is considered available; that is, it can be remembered under the proper circumstances. But only that information which actually is remembered is accessible. Thus, accessible information is always available, but available information cannot always be accessible.

The process of obtaining memory information from wherever it is stored is called retrieval. In order for information to be accessible, it must first be retrieved. Retrieval of information from long-term memory is a difficult process and is not always successful. Retrieval from short-term memory is considerably easier, and many models of short-term memory assume that if an item is available in short-term memory, it is automatically .accessible. While information in short-term memory is coded primarily by acoustic features (how the words sound when spoken), information in long-term memory is organized primarily according to what the words mean.

Retrieval System


While interference in short-term memory is based upon acoustic relationships, interference in long-term memory occurs among semantically related words. The most dramatic distinction between short and long-term memory systems lies in their respective capacities – the number of items each system can store. Short-term memory has a very limited capacity compared to the almost unlimited storage capacity of long-term memory.


1. Where do the sounds we hear first go?
2. What is necessary for a piece of information to be transmitted to LTM?
3. What problem does LTM suffer from? Why?
4. What does ‘the information is available in LTM’ mean?
5. How do STM and LTM differ in terms of available and accessible information?
6. In which memory system would the words ‘seat’ and ‘chair’ be confused? Why?
7. What is the main difference between STM and LTM?


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