Memory is the ability to remember something that has been learned or experienced. Memory is a vital part of the learning process. If you remembered nothing from the past, you would be unable to learn anything new. All your experiences would be lost as soon as they ended, and each new situation would be totally unfamiliar. Without memory, you would repeatedly have the same experiences for the "first time." You would also lose the richness that memory gives to life--the pleasure of happy remembrances as well as the sorrow of unhappy ones.
Scientists know little about what happens in the brain when it stores memories. However, storing new memories seems to involve both chemical changes in the nerve cells of the brain and changes in their physical structure. Research indicates that these chemical and physical changes occur in a tiny section of the brain called the hippocampus when a person stores new memories. The hippocampus is part of a larger structure called the cerebral cortex, which controls most higher brain functions. Such functions include problem solving and the use of language. Scientists have found that a memory is acquired by means of a series of consolidating events in the brain. However, more research will be necessary to discover precisely how memories are consolidated.
The memory system
Psychologists divide a person's memory system into three stages, each of which has a different time span. These stages are called sensory memory, short-term memory, and long-term memory.
Sensory memory holds information for only an instant. Suppose you look at a picture of a mountain. Information about the mountain passes through your eyes to your sensory memory, which briefly holds a nearly exact image of the picture. However, the image quickly fades, and it disappears in less than a second. For the information to last, you must transfer it rapidly to short-term memory.
Short-term memory can hold a fact as long as you actively think about it. You use short-term memory when you look up a telephone number and repeat it to yourself until you dial it. Unless you continually repeat this information to yourself, it will fade after about 20 seconds. However, some information from short-term memory enters long-term memory, where it may last a long time.
Long-term memory includes a huge amount of information, some of which lasts a lifetime. Information enters long-term memory as a result of either of two factors: (1) repetition or (2) intense emotion. A casual acquaintance, met briefly but on many occasions, will be remembered for a long time. The strong emotions of the first experience of falling in love or of the moments surrounding a car crash help place these events in long-term memory.
Measuring memory
There are three commonly used methods to measure how much a person remembers. These methods are (1) recall, (2) recognition, and (3) relearning. Suppose you give a party and someone asks you a few weeks later who was there. The simplest way to find out how much you remember is to list as many names as you can. This is the method of recall.
In recognition, the person asking about your guests would give you a list of names. The list would include names of people who were at the party and of others who were not. You could then indicate which people were there. Most people can recognize more facts than they can recall. As a result, most students perform better on multiple-choice tests than on essay tests.
In relearning, you would memorize the guest list after apparently forgetting it. Most people relearn information faster than they learned it the first time. Scientists regard the difference in the time required for the original learning and for the relearning as evidence of how much was remembered.
Why people forget
In general, people forget more and more as time passes. An hour after a party ends, you probably could remember most of the people who were there. Two days later, you might recall only a few of the guests. A month later, you probably would remember even fewer. Scientists have devoted much study to why the passage of time makes people unable to remember things they once knew. The chief explanations for forgetting include interference, retrieval failure, motivated forgetting, and constructive processes.
Interference occurs when the remembering of certain learned material blocks the memory of other learned material. If a friend moves, you may have difficulty recalling his or her new telephone number. The person's old number may keep coming to mind and interfering with your remembering the new one. But after you have thoroughly learned the new number, you may not even be able to recall the old one.
The above example illustrates two types of interference. Previously learned information may hamper a person's ability to remember new material. This hampering process is called proactive interference or proactive inhibition. Likewise, the learning of new facts may interfere with the memory of something previously learned. Such interference is known as
retroactive interference or retroactive inhibition.
Retrieval failure is the inability to recall information that has been stored in the memory. You probably have had the experience of being unable to think of a name or some other piece of information that was on the tip of your tongue. Later, the information came to you naturally and effortlessly. Such temporary loss of memory, which occurs frequently, is called retrieval failure. Scientists compare it to trying to find a misplaced object in a cluttered room. The information is not gone, but neither can it be recalled immediately.
Motivated forgetting is a loss of memory caused by conscious or unconscious desires. Scientists believe we forget many things because we want to do so. Motivated forgetting is related to a psychological process called repression. Repression involves forcing unpleasant feelings or painful experiences from the conscious mind into the unconscious. For example, people who like to gamble tend to remember most of the times they won--and forget those when they lost.
Constructive processes involve the unconscious invention of false memories. When you try to remember an event that happened months or years ago, you may recall only a few facts. Using those facts, you fill in the gaps with details that seem to make sense but may be untrue. The process of constructing probable happenings to tell a complete story is called
refabrication or confabulation. Refabricated memories seem real and are almost impossible to distinguish from memories of events that actually occurred.
Improving memory
Memory experts believe that people can, with practice, increase their ability to remember. One of the most important means of improving memory is the use of mental aids called mnemonic devices. A number of other techniques can be used to help people improve their memory.
Mnemonic devices are memory aids that include rhymes, clues, mental pictures, and other methods. One of the simplest ways is to put the information into a rhyme. Many people remember the number of days in each month by using a verse that begins, "Thirty days hath September. . . ."
Another method provides clues by means of an acronym, a word formed from the first letters or syllables of other words. A mental picture can be provided by the key-word method, which is particularly useful in learning foreign words.
Mental pictures can also be used to remember names. When you meet a person for the first time, pick out a physical feature of the individual and relate it to his or her name. For example, suppose you meet a very tall man named Mr. Shackley. You could imagine his bumping his head on the roof of a shack. In the future, this image will help you remember his name when you see or think of him.
To use mnemonic devices, one must first learn them--and often invent them. After mastering a mnemonic device, however, you can use it at any time you wish.
Other ways to improve memory. A good way to ensure remembering a piece of information is to study it long after you think you know it perfectly. This process is called
overlearning. The more thoroughly you learn something, the more lasting the memory will be.
Another memory aid involves making the surroundings in which you remember material similar to those in which you learned the material. For this reason, soccer coaches require players to practise under conditions similar to those of an actual game. Students often find it helpful to study in the room where they will be tested.
Still another method centres on organization. Try to organize information by creating a link between something you want to remember and something you already know. Suppose, for instance, that you want to fix in your mind the date when penicillin first came into use (1941): it may help to think of it becoming available in the second year of World War II (1939-1945).
Uncommon memory conditions
Unusually good memory.
We sometimes hear of someone who has a "photographic memory," which supposedly works like a camera taking a picture. A person with such a memory would be able to take a quick mental picture of a textbook page or a scene. Later, the person could describe the page or scene perfectly by causing the image to reappear in his or her mind.
No one actually has a photographic memory. However, some people have a similar ability called eidetic imagery. An eidetic image is a picture that remains in a person's mind for a few seconds after a scene has disappeared. People who have eidetic imagery can look at a scene briefly and then give a thorough description of the scene based on a mental image. But the image fades quickly and may be inaccurate. Eidetic imagery is rare. Only 5 to 10 per cent of all children have this ability, and most of them lose it as they grow up.
Amnesia can result from disease, physical injury, or emotional shock. Many cases of amnesia, even severe ones, are temporary, and the amnesic person regains his or her memory. A person who suffers a brain injury may forget events that occurred just before the injury. This inability to remember past events is called retrograde amnesia. The more severe the injury, the greater the memory loss. Boxers who receive a blow to the head might forget a few seconds of their lives. Someone who suffers major brain damage in a car accident might lose months or even years of memories. Some brain-injured people also have anterograde amnesia. This condition involves difficulty remembering events that occur after the injury is sustained. Both these types of amnesia also can be produced by emotional
shock
Additional resources
Horwarth, Ian. Think About It! Projects and Puzzles to Show You How People Think. Silver Burdett Press, Parsippany, New Jersey, U.S.A., 1996.
Reid, Straun. Improve Your Memory Skills. Usborne, London, 1988.
Baddeley, Alan. The Psychology of Memory. New ed. Harper and Row, London, 1985.
Higbee, Kenneth C. Your Memory. How it Works and How to Improve It. Piatkus, London, 1989.
McConkey, James. The Oxford Book of Memory. Oxford University Press, Oxford, U.K., 1996.
Melitzer, Milton. The Landscape of Memory. Viking Kestrel, New York, 1987.
