Short term memory describes the ability to recall a small number of events in the recent past that occurred more than a minute before. Most adults have no difficulty recalling such events, but people with certain types of brain damage and dementia lose this ability. They are unable, for example, to recall what day it is or whether someone has been in the same room as them recently. It is always the sign of a serious neurological disorder, but need not be a permanent condition. It is generally limited, depending on the person, to remembering five to nine separate elements. This is one of the reasons telephone numbers are only seven digits long - well within the short term memory of most people.
Short term memory is completely independent from long-term memory, learned skills or recognition. Long term memory can store an almost unlimited amount of items and information. A person suffering short term memory loss will most likely still be able to remember events from several decades before.
The most common test for this disorder is to read a list of three unrelated words to the patient, ask them to memorize them, then have them repeat the words a few minutes later. Most adults can perform this task easily.