Largely, how memory works is still a puzzle to scientists and researchers. Short-term memory and long-term memory are separate information storages, each acting independently from the other. Some researchers believe that in order for short-term memories to be transferred into long-term memory an individual must make a conscious effort to commit that information to memory, while other researchers believe that short-term memories transfer to long-term storage over time, with sleep helping this process. There are differences between the two memory storages, however, they also work together to achieve a common goal – to get an individual to remember certain facts and events.
The hippocampus is the center for memory. Memory-making is most simply described in three steps – input, storage, and readout (Facklam 1982). In more complicated terms, the making of memories is a process in which different parts of the brain work with the hippocampus to create lasting images and notes of facts and events.
When a memory is initially formed, the hippocampus associates information from different parts of the brain into a single memory. In this way, the hippocampus acts like an index of representations in the sensory processing regions of the brain. Molecular and cellular changes allow for the strengthening of connections between these regions over time. This allows for the memory not to be dependent on the hippocampus in order to be accessed (Preston 2007). In essence, when the hippocampus is involved in the memory process, it is referred to as “short-term memory.” Once the hippocampus has done its job and the memory is no longer dependent on it, it becomes “long-term memory.”
Damage to the hippocampus can result in the inability to form new memories. For example, in the film Momento, the main character, Leonard, damages his hippocampus and therefore cannot make new memories. However, he does not forget memories that were formed before he was injured because these memories were already transferred into long-term memory. This is why Leonard forgets who he met a few moments before, but can remember, perfectly, how to drive a car (Aamodt and Wang 2008). This is an example of short-term memory and long-term memory being different. If they worked on the same level, Leonard would have forgotten not only the people he met a few moments before, but also how to drive a car.
Short-term memory and long-term memory are separate storages of information, but they do work together to store information. The witnessing of an event must go through short-term memory before it can be stored as a long-term memory. If short-term memories are not consciously retained, they will not be stored as long-term memory (Thorn and Page 2008).
Information in the short-term memory storage will be forgotten if attention is not paid to it, as in the case of “in one ear and out the other.” Every individual perhaps has a memory of a parent repeating this saying when they ask their child to do a chore, and the child is either distracted or just does not want to hear it. That child will decide not to store that information as memory, and the chore will not be done, and the parent will evidently remark that what they say goes “in one ear and out the other.”
One fundamental difference between short-term and long-term memory is the rate at which information is forgotten. Information stored as long-term memory is, as evidence shows, never permanently forgotten. Information stored as short-term memory is forgotten quickly, unless there is a conscious effort to retain that information. For instance, most individuals can remember what they ate at a Christmas dinner the year before, but will not be able to remember what they had for lunch the previous day. This is because there is a conscious effort to remember a holiday event, whereas lunch on a normal day is routine, and therefore not important enough to remember. Many individuals will choose to only remember what is important to them.
A reason why some items may be remembered more easily than others may be due to the personal enjoyment certain memories bring. For instance, a trip to the dentist will always be harder to remember when compared to the memories of a trip to an amusement park. The memory of the visit to the dentist may be stored in one’s memory, but that memory will be visited less often. The memories of enjoyment are remembered more often, and are therefore willingly added to one’s memory.
Another difference between short-term and long-term memory, it is theorized, is that there is a limited capacity for information in short-term memory storage, while there is an unlimited capacity for information in long-term memory storage. This would perhaps explain why why memories transfer into long-term memory storage when rehearsed.
In addition, researchers have considered many theories for judging the capacity of short-term memory, such as basing the capacity of short-term memory on the number of items that can be recalled accurately. It is theorized that after a certain number of items, the short-term memory storage lets an item “slip out”, and therefore cannot hold anymore information without confusing the facts. This theory is likened to apples in a bucket. For example, a bucket may hold seven apples securely, but if an eighth apple is balanced on top of the seven, once the bucket is jostled, the apple will fall out of the bucket. Therefore, the maximum the bucket can hold is seven apples. Short-term memory storage, it is argued, works on the same principal (Thorn and Page 2008).
Alison Preston, an assistant professor at the University of Texas at Austin’s Center for Learning and Memory, claims that short-term memories are converted to long-term memories over time, not by will, as with the previous theory. Time, in this instance, allows the memory to become resistant to interference, whether that interference may come from disrupting factors, such as illness or injury, or from competing stimuli. Through time, memories are stabilized and transferred from short-term to long-term memory in a process known as “consolidation.” This is an example of short-term and long-term memory storages working together to form long-lasting memories.
This theory of time as critical for long-term memory storage also includes another factor – sleep. Memory consolidation processes may actually rely on sleep. For instance, a full night’s sleep reportedly enhances memory for virtual navigation tasks and associations between word pairs. However, sleep deprivation produces deficits in hippocampal activation while the brain tries to form new memories. This, in turn, results in poor retention. These findings, therefore, suggest that sleep plays a vital role in the consolidation of new memories (Preston 2007).
There are obvious differences in short-term and long-term memory, but each work with the other. There may be differences in the amount of information forgotten between short-term and long-term memory, and scientists and researchers may not agree whether information is transferred from short-term memory to long-term memory through a conscious effort or through time and sleep, but both short-term and long-term memory work toward the same goal, which is to get an individual to remember certain facts and events. Memory, as mysterious as it still is, is an important function of the human brain, a function which individuals could not live without.
-Aamodt, Sandra and Wang, Sam. (2008). Welcome to Your Brain: Why You Lose Your Car Keys but Never Forget How to Drive and Other Puzzles of Everyday Life. New York: Bloomsbury USA. 148.
– Facklam, Margery and Howard. (1982). The Brain: Magnificent Mind Machine. New York: Harcourt Brace Jovanovich Publishers. 64.
– Preston, Alison. (2007). How Does Short-Term Memory Work in Relation to Long-Term Memory? Are Short-Term Daily Memories Somehow Transferred to Long-Term Storage While We Sleep? Retrieved June 16, 2009, from Scientific American. http://www.scientificamerican.com/article.cfm?id=experts-short-term-memory-to-long-term
– Thorn, Annabel and Page, Mike. (2008). Interactions Between Short-Term and Long-Term Memory in the Verbal Domain. New York: Taylor & Francis. 17, 22.