Forgetting

Forgetting (retention loss) is a spontaneous or gradual process in which old memories are deleted from the memory storage. It is subject to delicately balanced optimization that ensures that only the least relevant memories are deleted, as well as a security process ensuring that dangerous information will not harm us. Forgetting can be prevented by repetition and/or evaluation of the information. As we are examining this part of mind, this function of mind, we shouldn't forget that this is still not an exactly explained property of mind.

History
One of the first people to study the mechanisms of forgetting was German psychologist Hermann Ebbinghaus. Using himself as the sole subject in his experiment, he memorized lists of three letter nonsense syllable words - two consonants and one vowel in the middle. He then measured his own capacity to relearn a given list of words after a variety of given time period. He found that forgetting occurs in a systematic manner, beginning rapidly and then leveling off. Although his methods were primitive, his basic premises have held true today and have been reaffirmed by more metholodogically sound methods.

Forgetting can have very different causes than simply removal of stored content. Forgetting can mean access problems, availability problems, or can have other reasons such as amnesia caused by accident.

In addition, information that has been stored may be permanently lost. Any information, to be able to permanently access our nervous system, needs a certain amount of time for biochemical changes to occur; if this amount of time is not given due to a disruption, the information is lost. Disruption can be caused by accidents, brain surgery, certain drugs, etc.; long-term memory is lost during the disruption. (Example: A football player involved in a major injury could remember exactly what had happened immediately after the incident, yet they could not remember it twenty minutes earlier.)

A debatable yet popular concept is "trace decay", which can occur in both short and long-term memory. This theory, applicable mostly to short-term memory, is contradicted by the fact that one is able to ride a bike even after not having done so for decades. It is believed that certain memories "trace decay" while others don't. Nevertheless, one thing is certain: sleep right after the memorization process cannot stop trace decay totally, but it can at least diminish it (explaining why it can be good to study shortly before sleep).