Memory is a complex mental activity. Under certain circumstances, parts of the activity may be made more efficient. Ability to retain increases until a person is about 20, after which it tends to decline. Illness, shock, or lack of sleep may impair memory.
Learning and memory are interrelated. Unless something is learned, whether intentionally or unintentionally, it cannot be retained. And unless mental material is retained for a measurable period of time, however brief, it has not been learned. Experiments have shown that the better the learning process, the longer and more completely the material is retained. For this reason, the principles of learning may be applied to memory.
A person learns more efficiently, and therefore retains better, when he understands the material, when it appeals to his interests, and when the material can be related to what he already knows. Practice is an aid to learning, especially if it is broken up with rest periods rather than massed into one “cramming” session.
Memory can be improved by the use of mnemonics, mental devices that relate material being memorized to something else—to previously learned material, a rhyme, or visual images, for example. A well-known mnemonic rhyme is the spelling rule “I before e, except after c, or when sounded as a as in neighbor and weigh.”
Remembering, or bringing memories to conscious thought, whether by recall or recognition, results from an appropriate stimulus. Hearing a certain song, for example, may stimulate a person to recall the first time he or she heard it, and under what circumstances. It is easier to recall a memory with many associations than one with a single association.
Forgetting is failure to retain stored mental material. The rate of forgetting is highest immediately after learning except for very young children. Psychologists believe that the most important cause of normal forgetting is the effect of new mental activity on what was previously learned. This effect is called retroactive inhibition. The more closely new mental activity resembles the old, the greater the influence of retroactive inhibition.
Some psychologists believe another cause of forgetting is repression. They maintain that if a person has emotional conflicts and is unaware of them, the person will tend to repress—that is, exclude from the conscious mind—memories that, if recalled, would produce anxiety by bringing the conflicts to consciousness.
Distortion is a kind of forgetting. If several persons witness an accident, each may recall it differently. This distortion may be in part because of false perception at the time of the accident. However, some distortion may occur later as wishes, fears, and prejudices affect the memory.