Short-term and long-term memory, while closely related, have many differences. Long-term memory is used to store information, memories, skill sets and procedural knowledge that can be readily retrieved when needed, both voluntarily and involuntarily. Short-term memory is designed to retain information for a brief period of time, after which it is then either forgotten or stored permanently in long-term memory, based on how actively it is used while in short-term memory.
One difference between these two types of memory is that information stays in short-term memory for only a very short period, while it is retained in long-term memory on a relatively permanent basis. People who cram for a test or exam may find that they can easily remember the information if they have studied it right before the test, but they may find that it has mostly disappeared a few days later. At a party, a person may notice that he cannot recall the name of another guest he has just met, despite being told the name only a few seconds earlier. Memories, skills and information stored in long-term memory, however, may be there for a lifetime.
Another key difference between short-term and long-term memory is the way in which the information stored in each is accessed. Information in short-term memory is easily accessible because it is temporarily right there, waiting to be used. People use short-term memory to remember things for a short period of time, such as a phone number they have looked up or potential answers to questions on a test for which they have studied at the last minute. They will be able to easily access those types of short-term memories right after they have committed them to memory but may not be able to recall them later if those memories do not make the transition into long-term memory. In long-term memory, memories and information can be accessed in several ways, including simply thinking about them, actively trying to remember them and by a connection that brings them to the surface.
Short-term and long-term memory also differ in the amount of information they can store. Short-term memory typically stores small amounts of information, because the information there is either moved to long-term memory for more permanent storage or lost entirely if not used before it is replaced with other information. While the amount of information that people can store in their short-term and long-term memory varies based on people’s individual abilities, there is an almost endless amount of information that can be stored in people’s long-term memories, especially because information, memories and knowledge accumulate over a person’s lifetime.