Encoding and retrieval are essential to the workings of the memory, and the fact that there are two main kinds of memory - short term and long term - is significant. Short term memory holds information for fairly short intervals, whereas long term memory stores information for a far longer amount of time. The relationship between both, as some Psychologists claim, is envisaged by stage theory. When information is encoded, it is stored in short term memory.

It must remain there for a long time in order for it to be finally stored in long term memory. The means for retaining it in short term memory is known as 'rehearsal'. By recalling information repeatedly, the chances of this information being transferred from short term to long term memory increases each time. Information stored in short term memory has a very limited time span, and there are two main reasons for this.

Information can be displaced. ie. old information somehow keeps being dumped whenever more recent information enters. Information can decay. ie.

where the memory trace becomes eroded over time by an unknown physiological process, so it's detail becomes progressively extinct. Often, each factor plays an equal role in memory loss. One way to encode information before it is erased in short term memory is by a process of organisation. This means the individual groups together or pairs off the necessary information given in order to remember it (store it in short term memory) rather than learning information off at random. This process of organisation makes it much easier to remember information. In order for learning to occur, the information in short-term memory must be manipulated or transformed.

The person will have to rehearse it, convert it, link it, or perform some other action with the information or else it will fade. Cognitive Psychologists present a framework for analyzing this process based upon teacher characteristics, knowledge and presentation; learner prior knowledge, strategies, cognitive processing and affective processing. They call this information manipulation process the encoding process. These strategies emphasize one or more of the four fundamental cognitive processes of the encoding process - selection, construction, integration and acquisition.

Rehearsal and affective strategies emphasize the selection and acquisition processes, while elaboration and organization emphasized the construction and integration processes. Copying, underlining and taking selective verbatim notes are obviously selective activities. However these activities can be accomplished without any transfer of knowledge into short-term memory, and it is not uncommon to discover that a student may not remember any of the facts in an essay after having spent ten minutes underlining 'important' passages. Similarly, chemistry students can organize lists of different types of acids without integrating the knowledge and transferring the lists to long-term memory. The necessary ingredient for the encoding process to occur is the 'active' or conscious state of the learner while completing the task. Hence, 'active' in the definitions of the four component processes.

Gleitman (1995) follows the thinking of most theorists today, claiming that it's the way in which the individual encodes and organisms the information provided, and how that information is processed and encoded psychologically. He states,' ... Most theorists believe that long term memories are formed by a more active process in which the subject's own ways of encoding and organising the material play a major role. As a result, they regard short term memory not so much as a temporary storage platform but as a mental workbench on which various items of experience are encoded - sorted, manipulate and organised. According to this view, whether the materials will be retained in memory long enough to become retrievable later does not depend upon a simple transfer from one storage container to another. Instead, it depends on how this material is processed (that is, encoded).

The more elaborate the processing, the greater the likelihood of later recall and recognition... '; There are three main kinds of encoding in short term memory: Acoustic (phenom ic) encoding, Visual encoding and semantic encoding. Acoustic encoding is carried out by sub-vocal sounds being rehearsed. For example, in order to remember a new telephone number, an individual repeats the number out loud.

Visual encoding is storing information as pictures rather than sounds. This refers mainly to non-verbal information, especially if the information provided is not easily described in words. semantic encoding is the application of meaning to information, relating it in some way to aome thing abstract. Fro example, a historian may well relate a set of given numbers to dates of events in history in order to store it in short term memory.

In long term memory, the primary encoding is semantic. If an individual is watching a film for the first time, for example, he or she may not remember every scene in the film afterwards, but the plot is clearly remembered. Though semantic encoding is the primary encoding used in long term memory, acoustic and visual encoding are also apparent. With encoding comes retrieval.

An individual may have learned (stored) a piece of information, but cannot recall it on a certain occasion because the memory trace is unattainable. This can be restored by an appropriate retrieval cue, a stimulus that opens the path to the memory. There are two possible hypothesis concerning short term memory retrieval. When related items are studied one at a time until the information being sought is retrieved, a 'serial s each' has occurred, whereas when the activation of a particular item reaches a decisive point, 'activation' of information occurs. The more information stored within short term memory means less activation for the particular item. In long term memory, the serial search needs a retrieval cue; the search is much more slower if more cues are used due to the fact that there is more information that needs scrutinized.

'Spreading activation' occurs in long term memory. When a certain pathway is activated and followed, the information becomes more specialised, so the path narrows. All these views, though, refer to explicit retrieval, but there is also implicit retrieval - a familiar feeling that cannot be recalled by the individual. According to one theorist, something is retrieved so that 'familiar' feeling is felt. But there is no source memory and no knowledge where that memory came from.

This may also explain the notion of 'de ja-vu', where a peculiarly familiar event or place arouses some memory trace either by association, similarity or something else, but the arousal is purely implicit. In conclusion, what is the relationship between encoding and retrieval? Well, retrieval is most likely successful if the context at the time of retrieval approximates that during original decoding, and the role of retrieval can help explain why there are better ways of encoding than others for later recall (the compatibility principle). This may help in storing information more efficiently, but there is a more important aspect to this - it allows information to be found more easily when being retrieved. The key to good encoding is to provide means for later retrieval. There is another form of rehearsal (mentioned earlier) besides maintenance rehearsal, which is quite effective - elaborate rehearsal.

ie. mental activities by which the individual organisms the items he wishes to remember, encodes them, or them to one another and to any stored information in long term memory. It may sound similar to maintenance rehearsal, but elaborate rehearsal increases the probability of later retrieval. Whatever else seen and thought about at the time of rehearsal will be linked to some of the items and can also serve as a retrieval cue later..