by Anushki Natasha Bodhinayake
Can you recall the powerless feeling of not being able to remember something at say, an examination or interview? And yet, are you aware of the vast amount of information you are able to recall simply on demand? Psychologists have attempted to research this very phenomenon of why we are able to successfully remember some things on certain occasions and fail to do so at other times.

It is widely accepted that there are three stages involved in memory: Encoding of material to be remembered, Storage of that material and finally Retrieval. Failure at any one stage will interfere with memory. For example, if an item has not been successfully encoded or stored it will not be available from memory.

Different forms of forgetting have been identified:

Trace decay: memory is believed to generate a "trace" in the brain. With time, if it is not attended to, this trace gradually weakens. This theory may explain why we are unable to remember the details of the first lesson of a school term month later, while we are able to recall the majority of it a day later.

Displacement: it has been proven that our short-term memory has a capacity of seven - plus or minus two - items of information. This means that at a given time, any more than either five or nine items of information will effectively "push out" existing information. This may explain why we find it easier to remember a telephone number if it is divided rather than remembering it as a whole, i.e. 346 - 5578 rather than 3465578.

Interference: this form of forgetting has been further divided into Retroactive inhibition and Proactive inhibition. Retroactive inhibition refers to when new learning interferes with an existing memory, for example, when changing your telephone number, you will soon remember your new number in place of your old number. Proactive inhibition occurs when an existing memory interferes with information to be remembered. For example, a man may park his car in the same place every day and then one day when he is forced to park somewhere else he may not be able to recall the new parking space, owing to the memory of his usual space.

Stereotypes: it has been proven that if one holds a certain strong belief about a person or situation, one is likely to remember in accordance to that belief. This leads to distorted memory causing other related information to be excluded and, in effect, forgotten.

Anushki Natasha Bodhinayake

Repression: according to Sigmund Freud, painful experiences which would provoke overwhelming anxiety if allowed to enter into consciousness, are repressed and stored in the unconscious. Repression causes information to be inaccessible rather than forgotten, i.e. information has been encoded and stored but can not be retrieved from memory easily-although, hypnosis is believed to be effective in retrieving these memories.

State (or context) dependent forgetting: ones's state or context at the time of acquisition of memory is known to have an effect on memory. If the states match, for example, if one was drunk when learning the material, and is drunk also, when asked to recall the material, then the recall is actually known to improve!

It is common knowledge that forgetting occurs when one is under stress. For example, a witness to a bank robbery will remember less details prior to the incident, if a weapon was involved than if no weapon was involved. Similarly, one who was involved in a serious accident would remember less prior to the incident owing to stress alone, even in the absence of neurological damage.

Reconstructive memory: there is a special form of forgetting associated with reconstructive memory, observed in eye-witness testimony accounts. This occurs when one recalls events according to what the listener is expecting to hear. For instance, if the question was worded, "Did you see the broken window?.." It is assumed that there was indeed a broken window. Whereas, if the question happened to be, "Did you see a broken window?..." this is not so obvious. Subsequently, the question using "the" is more likely to prompt the answer "yes" than the question using "a" Ð even if there was no broken window. This tendency should be taken into consideration in questioning so as to avoid untrue statements from witnesses.

Clinical forms of forgetting (Amnesia): amnesia may be caused by damage to the brain through a stroke, alcoholism or ageing itself. Ageing particularly is associated with a type of forgetting linked with Alzheimer's disease, (popularly knowns as "Senile Dementia".) A patient who manifests Alzheimer's disease initially fails in the short-term memory: such patients may bring out exquisite details of their early childhood and even impress observers as possessing a good memory. In alcoholism too, short-term memory may be disturbed and the alcohlic may make things up (confabulate) to cover up his deficit.

In daily life, we are surrounded by an infinite range of information and it is impractical and probably impossible to retain it all; it may therefore be logical to think that forgetting has a functional role and we forget in order to retain only the relevant information.