Information in LTM is stored in interrelated networks of schemas which are the cognitive frameworks that help people organize and interpret information. Schemas guide recognition and understanding of new information by providing expectations about what should occur. Since LTM is organized into schemas, instructors should consciously look for ways to make training relevant and meaningful enough for the learner to transfer new information to LTM. This can be accomplished by activating existing schemas before presenting new information. For example, a brief review of the previous lesson via discussion, video, questions, etc.

The moment people learn something new and add it to their repertoire of knowledge and skill, they are confronted with a second task: the task of remembering it. Remembering is a challenge because of a natural feature of human memory-forgetting. Forgetting is such an apparent part of human memory that it is often the first thing that people think of when they bring up the topic of memory.

The following section discusses how remembering and forgetting happens in predictable ways that help keep human memories tuned to the demands of everyday life. Memories help people keep fresh precisely those things needed next, and let slip those things that have outlived their usefulness. Understanding the factors that determine what is remembered and what is forgotten helps instructor and learner get the most from memory.

The ability to retrieve knowledge or skills from memory is primarily related to two things: (1) how often that knowledge has been used in the past; and (2) how recently the knowledge has been used. These two factors are called frequency and recency of use. Frequency and recency can be present individually or in combination.

Frequency and recency—knowledge that enjoys both frequency and recency is likely to be retrieved easily and quickly. This is knowledge much used in the past that continues to be used in the present. This is the ideal situation for knowledge and skills that need to be used.

Frequency only—knowledge that has been used much in the past but that has not been used recently is vulnerable to being forgotten. This type of knowledge is likely to be retrieved slowly or not at all. To retrieve this knowledge and skill, some recent rehearsal or practice needs to be added in order to refresh the memory.

Recency only—knowledge that has been recently used but has not been used in the past is knowledge that has been recently acquired. This type of knowledge is particularly vulnerable to being forgotten since there is little to distinguish it from “throw away” knowledge, such as an hourly weather broadcast. To remember this knowledge requires a program of regular rehearsal to build up its frequency.

Forgetting, which refers to loss of a memory, typically involves a failure in memory retrieval. The failure may be due to the decay or overwriting of information which has been temporarily stored in STM, but generally forgetting refers to loss of information from LTM. The information is not lost, per se, it is somewhere in the person’s LTM, but he or she is not able to retrieve and remember it.

Why do people forget? Why don’t we remember everything? Do we need to remember everything? Most of the information people are exposed to each day has a short period of usefulness with little need to retain it. For example, why would anyone need to remember the details of an hourly weather broadcast ten years ago?

Thus, forgetting knowledge is not always a bad thing. For example, forgetting old information keeps new information up to date. Many theories on why people forget have been offered to explain the phenomenon, among them retrieval failure, fading, interference, and repression or suppression.

Retrieval failure is simply the inability to retrieve information, that tip-of-the-tongue phenomenon when a person knows the meaning of a word, or the answer to a question, but cannot retrieve it. It is also caused by the fact that sometimes people simply do not encode information well and the information never makes it to LTM or is lost before it can attach itself to the LTM. This is sometimes referred to as failure to store.

The theory of fading or decay suggests that a person forgets information that is not used for an extended period of time, that it fades away or decays. It had been suggested that humans are physiologically preprogrammed to eventually erase data that no longer appears pertinent.

On the other hand, experimental studies show that a hypnotized person can describe specific details of an event, which normally is beyond recall. Apparently the memory is there, locked in the recesses of the mind. The difficulty is summoning the memory to consciousness or retrieving the link that leads to it.

Interference theory suggests that people forget something because a certain experience has overshadowed it, or that the learning of similar things has intervened. This theory might explain how the range of experiences after graduation from school causes a person to forget or to lose knowledge. In other words, new events displace many things that had been learned. From experiments, at least two conclusions about interference may be drawn. First, similar material seems to interfere with memory more than dissimilar material; and second, material not well learned suffers most from interference.