Most traditional models of memory contain only two stages of memory, short-term and long-term memory. When it comes to learning, I would propose a third type of memory that has a very large capacity but has an intermediate length of time that lasts longer than short-term but could not be considered long-term. I suppose that this memory could be called intermediate memory.
Short-term memory is exactly what the name implies, memory for the short term. It is the memory you are using to feed your thinking. The number of items you can hold in short-term memory is between about four and eight (5±2 or 7±2 depending on the research). You keep items active in short-term memory by rehearsing them in your head. You know what this feels like when you get a phone number. As long as you can keep repeating it in your mind, you don’t forget. As soon as another item comes along, you begin to lose part of the number. You can chunk information together and make it one item, so (keeping with the phone number analogy) a familiar area code can be treated as a chunk, even though it is three numbers long.
The biggest problem with memory and learning is the subjective experience of working with short-term memory. Because we have to repeat information over and over in order to keep it active in short-term memory, the natural assumption is that the way we move things from short-term memory (or from intermediate memory) into long-term memory is to repeat it over and over. Although this will work, eventually, for raw information, the processing is very shallow and all that will be moved into long-term memory are the facts or salient bits of the information. This is the way things like multiplication tables are learned. By working at the bits of information over a prolonged period of time, the bits of information becomes stored in long-term memory, but the understanding has to be taught separately.
Long-term memory is the stable, durable, long-term memory storage construct that we think of when we delve into our memories for information or knowledge that we can recall after long periods of time. Long-term memory is organized semantically or by meaning. Long-term memory is developed as new information is tied to information or knowledge that you already have in long-term memory. The ties that bind new memories to already stored knowledge that allow you to retrieve memories are referred to as memory traces. Building strong memory traces is what makes long-term memory useful. A memory isn’t very useful if it can’t be retrieved because the memory trace is not available.
This brings me to the third type of memory that I am proposing, intermediate memory. Intermediate memory has a large capacity. Not unlimited, as some proponents of long-term memory have argued for, but far larger than the four to seven items that research demonstrates is the capacity for short-term memory. Intermediate memory can also last far longer than short-term memory but the information in intermediate memory is usually not tied to long-term memories in any permanent manner. Intermediate memory is the kind of memory that allows you to remember what you ate for dinner yesterday evening, but is limited, in that you can’t remember what you ate for dinner last Thursday. This is a fairly large capacity memory store where transient (up to two or three days) memories are held and then discarded if there is no reason to go through the difficulty of tying them to long-term memory.
The building of memory traces between short-term memories and intermediate memories to long-term memories requires time and energy. As the brain is a conservative organ (doesn’t like to burn needless energy), what you ate for lunch on Wednesday is not tied to anything in long-term memory – unless you have a good reason for remembering. It appears that sleeping is vital for building memory traces between long-term memory and intermediate memory. This is the reason why turning intermediate memories into long-term memories takes time.
When information is processed at a shallow level, it will be transient and very little will be transferred into long-term memory. If a great deal of information is presented too quickly, there is not the time for deep processing and very little will be processed deeply. This is what happens in lectures that are heavily loaded with information. This is also what happens when students cram for exams. The information can be held for a day or two, but because of the lack of time, and often the lack of engagement, the information in intermediate memory fades quickly and is never tied to information that is already held in long-term memory.
If the process of learning material is deep, information is moved into long-term memory and tied to other, related information and some understanding begins to emerge. Information that becomes embedded in long-term memory informs us of the reality that we live in. Because the information is tied to information that is already there, the reality that we experience is rarely changed with new information. Our understanding of the world might be enriched with new information, but the accuracy of our representation of reality remains the same. Other higher order thinking processes or prolonged experiences with the information is required for the information to become a better representation of reality. Something that does not happen often in formal education.
We know how to fix this in learning but we rarely do. Too many other important things keep us from helping our students really learn in a way that helps them gain a better representation of reality.