Monday, January 15, 2007

memorising technique... mnemonic

Alhamdulillah, i just pass my winter exams....lega sangat2. some of my friends sekarang ni ade kt uk, germany...eurotrip. aku kt sini aje, maybe abiskan jln kt bandar simferopol ni....disamping masalah universal...apelagi, ekonomi la. oklah, ni tips untuk memorise material for exams. maybe dah terlambat utk sem ni, tp sem depan2 still ade, still exam. to my friends yg still struggling for exams good luck...agi idup, agi ngelaban!!

Mnemonic any device for aiding the memory. Named for Mnemosyne, the personification of memory in Greek mythology, mnemonics are also called memoria technica. The principle is to create in the mind an artificial structure that incorporates unfamiliar ideas or, especially, a series of dissociated ideas that by themselves are difficult to remember. Ideally, the structure is designed so that its parts are mutually suggestive. Grouping items in rhymed verse has long been a popular >mnemonic technique, from the “gender rhymes” of the Latin grammars to the verse for remembering the number of days in the months (“Thirty days hath September, April, June and November . . . ”).

Numerous attempts have been made to invent mnemonic systems—generalized codes to improve all-around capacity to remember. The Greek and Roman system of mnemonics was founded on the use of mental places and signs or pictures in terms of the location of the items of interest. The method combines a familiar structure locus and the item or thing to be remembered. This mnemonic method, which is referred to as loci et res, is an effective way to remember a series of items in serial order. The most usual method is to choose a large house, of which the apartments, walls, windows, statues, and furniture were severally associated with certain names, phrases, events, or ideas by means of symbolic pictures; to recall these it is only necessary to search over the apartments of the house until the particular place is discovered where they had been deposited by the imagination. In accordance with this system, if it is desired to fix a historic date in the memory, it is localized in an imaginary town divided into a certain number of districts, each with 10 houses, each house with 10 rooms, and each room with 100 quadrates, or memory places, partly on the floor, partly on the four walls, partly on the roof. Using this system, the traditional date of the invention of printing in Europe (1440) could be fixed in the memory by mentally placing a book or some other symbol of printing in the 40th quadrate, or memory place, of the 4th room of the 1st house of the imaginary town.

Scientific interest in mnemonics was heightened in 1968 when the renowned Soviet psychologist Aleksandr R. Luria wrote The Mind of a Mnemonist, which suggested the field was worthy of deeper psychological study. Luria was particularly impressed with the ability of individuals to remember long lists of numbers for periods of years.

Mnemonists use a variety of procedures to facilitate recall. One method, called linking, associates any pair of items—a pen and a chair, for example—and then links those items with a third, the chain proceeding indefinitely. Interaction, and not mere association, is necessary; one could imagine the pen writing on the chair. This method has proven effective with grammar-school children as well as with adults. Other methods include rhymes (“i before e, except after c”) or substitution (the name Tchaikovsky can become “chew-cow-ski”; Reagan becomes “ray-gun”; etc.). One point stressed by mnemonists is that the imagery has to be bizarre if it is to be effective. Simple or common associations are said to be quickly forgotten.

In fact, mnemonic devices, all of which depend upon the use of some method of coding of what is to be remembered, may be very useful in limited fields, especially if the coding is made up by the person who is going to use it. Completely generalized and impersonal mnemonic systems are apt to break down, largely because of their inevitable complexity and ambiguity; thus their importance has declined.

Memory the retention and retrieval in the human mind of past experiences.
That experiences influence subsequent behaviour is evidence of an obvious but nevertheless remarkable activity called remembering. Learning could not occur without the function popularly named memory. Practice results in a cumulative effect on memory leading to skillful performance on the tuba, to recitation of a poem, and even to reading and understanding these words. So-called intelligent behaviour demands memory, remembering being prerequisite to reasoning. The ability to solve any problem or even to recognize that a problem exists depends on memory. Typically, the decision to cross a street is based on remembering numerous earlier experiences.

Practice (or review) tends to build and maintain memory for a task or for any learned material. Over a period of no practice what has been learned tends to be forgotten; and the adaptive consequences may not seem obvious. Yet, dramatic instances of sudden forgetting (as in amnesia) can be seen to be adaptive. In this sense, the ability to forget can be interpreted to have survived through a process of natural selection in animals. Indeed, when one's memory of an emotionally painful experience leads to severe anxiety, forgetting may produce relief. Nevertheless, an evolutionary interpretation might make it difficult to understand how the commonly gradual process of forgetting survived natural selection.
In speculating about the evolution of memory, it is helpful to consider what would happen if memories failed to fade. Forgetting clearly aids orientation in time; since old memories weaken and the new tend to be vivid, clues are provided for inferring duration. Without forgetting, adaptive ability would suffer; for example, learned behaviour that might have been correct a decade ago may no longer be. Cases are recorded of people who (by ordinary standards) forgot so little that their everyday activities were full of confusion. Thus, forgetting seems to serve the survival of the individual and the species.

Another line of speculation posits a memory storage system of limited capacity that provides adaptive flexibility specifically through forgetting. In this view, continual adjustments are made between learning or memory storage (input) and forgetting (output). Indeed, there is evidence that the rate at which individuals forget is directly related to how much they have learned. Such data offer gross support of contemporary models of memory that assume an input-output balance.

Whatever its origins, forgetting has attracted considerable investigative attention. Much of this research has been aimed at discovering those factors that change the rate of forgetting. Efforts are made to study how information may be stored; that is, to discover the ways in which it may be encoded. Remembered experiences may be said to consist of encoded collections of interacting information; and interaction seems to be a prime factor in forgetting.

Psychologists of the modern era, from their earliest speculations about remembering to the formulation of most of their latest experimentally based views, commonly have assumed that the critical problems are concerned with the physiological mechanisms by which events and experiences can be retained so that they can be mentally reproduced, either in their original mode or with the assistance of signs and symbols that are regarded as equivalent to that mode. Memory is thus usually considered to function perfectly in proportion to its literal accuracy of reduplication. Investigators have generally supposed that anything that influences the behaviour of an organism endowed with a central nervous system leaves—somewhere in that system— a “trace” or group of traces. So long as these traces last they can, in theory, be restimulated and the event or experience that established them will be remembered. The experimental psychology of remembering—all modern experts claim to base their conclusions upon experimental evidence—endeavours to discover methods for identifying the necessary and sufficient conditions for the persistence and length of persistence of traces and for their restimulation.

Measuring retention

Standard sentences, prose passages, and poems have been used to control input in studies of retention; but discrete verbal units (such as words or sets of letters) are most frequently employed. The letters usually comprise lists of consonant syllables (three consonants; e.g.,RQK) or so-called nonsense syllables (consonant-vowel-consonant; e.g., ROK). The order in which verbal units are to be learned and to be recited may be left to the subject (free recall). A schoolchild who can recite the names of all African countries probably has learned such a free-recall task. Units also can be presented serially (in a constant order), the subject being asked to recite them in that order; reciting the alphabet in the usual way represents such serial learning.

Pairs of words may be offered; in such paired-associate tasks the subject eventually is asked to produce the missing member of each pair when only one word is shown. This is akin to learning English equivalents for words from another language.

For these and similar tasks investigators commonly permit subjects enough practice trials to reach some preselected criterion or level of performance. This level effectively defines an immediate retention score against which later forgetting may be measured. Subsequent tests of retention are then made to investigate the rate at which forgetting proceeds. This rate tends to vary with the methods used, basically those of recall, recognition, or relearning.

Subjects may be asked to reproduce (recall) previously learned data in any order or in the original order in which they were learned.
In a free-recall test the instructions might be: “Yesterday you learned a list of words; please write as many of those words as you possibly can as they occur to you.” For the paired-associate task the subject may be told: “Yesterday you learned some pairs of words; I will show you one word from each pair and you try to give the other.” He may be paced, being limited to a few seconds to produce each word; or he may be unpaced, being given no rigidly specified limits.

If retention of any kind is to be measured over different periods (e.g., an hour, a day, a week) a separate group of individuals should be used for each period. The reason is that the very act of remembering constitutes practice that keeps memory lively, tending to give misleading underestimates of the rate of forgetting if the same subjects are tested over successive intervals.


The subject's task is simpler in tests of recognition, since reproduction or retrieval (as in recall) is not required. The subject simply is asked to remember previously presented information when it is offered to him again. For example, he may be given a list of words for study; on the subsequent test of retention these are mingled with additional words, the subject being asked to identify (recognize) the original words. Apparently the recognition test stresses ability to choose between “old” (studied) data and “new” words, although this need not mean that choices are based only on temporal discrimination (awareness of time distinctions).

In an alternative variety of recognition test, each word studied might be paired with a new one, the task being to choose the old member of each pair. Or, the test words might be presented one at a time for identification as old or new. Sometimes learning and testing are combined: a very long list of words may be presented one at a time, some being repeated; the task is to recognize the repeats.

Some recognition tests stress memory of the order of presentation. The subject learns a serial list (reciting in a prescribed order); the list then is scrambled, and he is tested on his ability to rearrange it appropriately. Order may be based on how units are arranged in space (e.g., printed on a page) or on their numerical position in a series or on associative information. Thus, if a paired-associate list has been learned, the test may consist of the unmatched presentation of all units with a request to pair them properly. This sort of recognition seems to emphasize associative attributes. If some elements on the test were not presented originally, the temporal attribute also may be involved.


The number of successive trials a subject takes to reach a specified level of proficiency may be compared with the number of trials he later needs to attain the same level. This yields a measure of retention by what is called the relearning method. The fewer trials needed to reach the original level of mastery, the better the subject seems to remember. The relearning measure sometimes is expressed as a so-called savings score. If 10 trials initially were required, and five relearning trials later produce the same level of proficiency, then five trials have been saved; the savings score is 50 percent (that is, 50 percent of the original 10 trials). The more forgetting, the lower the savings score.

Although it may seem paradoxical, relearning methods can yield both sensitive and insensitive measures of forgetting. Tasks have been devised that produce wide differences in recall but for which no differences in relearning are observed. (Some theorists attribute this to a form of heavy interference among learned data that has only momentary influence on retention.) Six months or a year after initial learning, some tests may give zero recall scores but can show savings in relearning.

When relatively long retention intervals (usually hours or days) are used, the methods are said to involve long-term memory. In a sense, methods for studying short-term memory are miniaturized versions of these. A list may be as short as one item, level of proficiency is very low, and retention intervals are in seconds (or minutes at most).

For example, the subject may be shown a single nonsense syllable for a few seconds' study. Next he is given a simple task (such as counting backward) to occupy him for a half minute so that he cannot rehearse, and then is asked to recall the syllable. Forgetting is observed to occur over such short intervals, tending to be greater when length of interval increases, as in long-term memory. The same procedure can be used with a single paired-associate item or with a short list of four or five pairs. In a short-term counterpart of serial learning, a string of about eight single-digit numbers or letters is presented very rapidly (say, two per second), and the subjects are asked to recall them in the order in which they were presented. Recognition tests also can be adapted for measuring short-term retention. When only one presentation is used for learning, however, relearning measures are obviously unfeasible.

Time-dependent aspects of retention; storage and retrieval

Some workers theorize a distinct short-term memory system of sharply limited capacity that can retain information perhaps only a few seconds and a long-term system of relatively unlimited capacity and retention.
Among typical people, short-term function seems limited to about seven separate units (e.g., seven random letters or unrelated common words). Thus, one may consult a telephone directory and forget the number before dialing is completed. Information seems to enter long-term storage by such processing as rehearsal and encoding, as if short-term retention is a way station between incoming information and more enduring memory.
Other theorists do not distinguish short- and long-term systems as inferred from observed differences in capacity and retention. Positing only one storage system, they attribute short-term phenomena to very low levels of learning. Those who postulate distinct systems point to the results of injury to a specific brain region (the hippocampus): (1) information stored prior to hippocampal damage seems to be retained; (2) sufferers seem incapable of new long-term storage; (3) the short-term functions appear to be unimpaired and subjects perform as well as ever in tests of immediate memory (e.g., for a set of random numbers). It is as if new information no longer can be transferred from some sort of short-term system to relatively enduring storage.

Other data that bear on the controversy among theorists come from studies of people without known brain injury. When one has just seen a new list of words one at a time, the initial words in the list tend to be recalled best (primacy effects), those at the end next best (recency effects), while items from the middle are least likely to be recalled. This is quite consistently found as long as recall begins immediately following presentation of the last word. If, however, a short interval follows, during which the subject is otherwise occupied to prevent rehearsal, the recency effect may completely disappear; words at the end are no better recalled than those in the middle. Primacy effects are essentially undisturbed, while a delay as short as perhaps 15 seconds is enough to abolish the recency phenomenon. Although some suggest that recency effects depend on a separate short-term memory system and that primacy effects are mediated by a long-term system, a single memory function also may be invoked to accommodate the findings. Nevertheless, interest is growing in multisystem theories on the grounds that they enhance appreciation of the processes involved in establishing relatively enduring memory.

Investigators concerned with physiological bases for memory seek a kind of neurochemical code with enough stability physically to produce a structural change or memory trace (engram) in the nervous system; mechanisms for decoding and retrieval also are sought. Efforts at the strict behavioral level similarly are directed toward describing encoding, decoding, and retrieval mechanisms as well as the content of the stored information.

One way to characterize a memory (or memory trace) is to identify the information it encodes. A learner may encode far more information than is apparent in the task as presented. For example, if a subject is shown three words for a few seconds and (after 30 seconds of diversion from rehearsal) is asked to recall and then another triad of words is given under the same procedure, then another, and so on, then if all triads share some common element (e.g., all are animal names), poorer and poorer recall is observed on successive trials. Such findings may be explained by assuming that the learner encodes this animal category as part of his memory for each word. Initially, the common code might be expected to aid recall by sharply delimiting the word population. Successive triads, however, should tend to be encoded in increasingly similar ways, blurring their unique characteristics for the subject. An additional step provides critical supporting evidence for such an interpretation. If a final triad of vegetable names is unexpectedly presented, recall recovers dramatically. The subject tends to reproduce the vegetable names much better than he does those of the last animal triad; recall is about as efficient as it was for the first three animal names. This particular shift clearly seems to provide escape from earlier confusion or blurring, and it may be inferred that a common conceptual characteristic was encoded for each animal name.

Any characteristic or attribute of a word may be investigated in this way to infer whether it is incorporated in memory. When recall does not recover it would seem that the manipulated characteristic has little or no representation in memory. For example, grammatical class typically does not appear to be encoded; decrement in recall produced after a series of triads consisting of verbs tends to continue when a shift is made to three adjectives. Such an experiment does not indicate what common encoding characteristic might be responsible for the decrement, suggesting only that it is not grammatical class.

Encoding mechanisms also may be inferred from tests of recognition. For example, subjects study a long list of words, being informed of a multiple-choice memory test to follow. Each word studied is made part of a test item that includes other carefully chosen new words (distractors). Distractors are selected to represent different types of encoding the investigator suspects may have occurred in learning. If the word presented for study is chosen by the subject, little can be inferred about the nature of the encoding. Any errors, however, can be most suggestive. Thus, if the word presented for study was TABLE, the multiple-choice item might be TABLE, CHAIR, ABLE, FURNITURE, PENCIL. If CHAIR is incorrectly selected, it may be suspected that this associatively related word occurred to the subject implicitly during learning and became so well encoded that the subject later could not determine whether it or TABLE had been presented. If the wrong choice is ABLE, acoustical resemblance to TABLE may have contributed to the confusion. If FURNITURE is erroneously chosen, perhaps conceptual category was prominent in the encoding.

Since it is not related in any obvious way to TABLE, the word PENCIL may be intended as a control, unlikely to be a part of the memory for TABLE. If this is the case, subjects should be more likely to select distractor words other than PENCIL (if indeed they have been encoded along with TABLE).

Although a subject may have encoded in ways suggested by particular distractors, he still may be able to choose the correct word. Or he may have encoded in ways not represented by the distractors.
Evidence has been accumulating to suggest that a long-term memory is a collection of information or of attributes that can serve in discriminating it from other memories and can function as retrieval cues. In addition to verbal attributes, visual images may be a part of the memory; emotional responses produced at the time the memory is established may be incorporated.

The common experience of having a name or word on the tip of the tongue seems related to specific perceptual attributes. In particular, people who report the “tip-of-the-tongue” feeling tend to identify the word's first letter and number of syllables with an accuracy that far exceeds mere guessing. There is evidence that memories may encode information about when they were established and about how often they have been experienced. Some seem to embrace spatial information; e.g., one remembers a particular news item to be on the lower right-hand side of the front page of a newspaper. Research indicates that the rate of forgetting varies for different attributes. For example, memories in which auditory attributes seem dominant tend to be more rapidly forgotten than those with minimal acoustic characteristics.

If a designated (target) memory consists of a collection of attributes, its recall or retrieval should be enhanced by any cue that indicates one of the attributes. For example, on failing to recall the term horse (included in a list just seen), one may be told that there was an animal name among the words. Or he may be asked if an associate term (say, barn or zebra) helps him think of a word he missed. While some additional recall has been observed with this kind of help, failures are common even with ostensibly relevant cues. Though it is possible that the cues frequently are inappropriate, nevertheless, if words were not learned (encoded or stored) with accompanying attributes, cuing of any kind should be ineffective.

Theories of forgetting

When memory of past experience is not activated for days or months, forgetting tends to occur; and any theory of forgetting must cope with this primitive observation. Such auxiliary phenomena as differences in the rates of forgetting for different kinds of information also must be accommodated.

It has been theorized that as time passes the physiological bases of memory tend to change. With disuse, it is held that the neural engram (the memory trace in the brain) gradually decays or loses its clarity. While such a theory seems reasonable, it would, if left at this point, do little more than restate behavioral evidence of forgetting at the nervous-system level. Decay or deterioration does not seem attributable merely to the passage of time; some underlying physical process needs to be demonstrated. Until a neurochemical basis for memory can be more explicitly described, any decay theory of forgetting must await detailed development.

A pre-eminent theory of forgetting at the behavioral level is anchored in the phenomena of interference; in what are called retroactive and proactive inhibition. In retroactive inhibition, new learning interferes with retention of the old; in proactive inhibition, old memories interfere with the retention of new ones. Both phenomena have great generality in studies of any kind of learning, although most research among humans has considered verbal learning.

People may, for example, learn two successive verbal lists; the next day some are asked to recall the first list and others to recall the second. Still a third (control) group learns only one list and is asked to recall it a day later. People who learn two lists almost unfailingly will recall much less than do those in the control group. The amount by which controls exceed those who recall the first list is a measure of retroactive inhibition; the degree to which they are better than those who recall the second list is a measure of proactive inhibition. While retroactive inhibition usually will be observed in relearning, it is unusual to detect proactive deficit under such circumstances.

Theorists attribute the loss produced by these procedures to interference between list-learning tasks. When lists are constructed to exhibit varying differences, the degree of interference seems to be related to the amount of similarity. Thus loss in recall will be reduced when two successive lists have no identical terms. Maximum loss generally will occur when there appears to be heavy (but not complete) overlap in the memory attributes for the two lists. One may recall parts of the first list in trying to remember the second and vice versa. (This breakdown in discrimination may reflect the presence of dominant attributes that are appropriate for items in both lists.) Discrimination tends to deteriorate as the number of lists increases, retroactive and proactive inhibition increasing correspondingly, suggesting interference at the time of recall.

In retroactive inhibition, however, all of the loss need not be attributed to competition at the moment of recall. Some of the first list may be lost to memory in learning the second; this is called unlearning. If one is asked to recall from both lists combined, first-list items are less likely to be remembered than if the second list had not been learned. Learning the second list seems to act backward in time (retroactively) to destroy some memory for the first. So much effort has been devoted to studying conditions that affect unlearning that it has become a major topic in interference theory.

Retroactive and proactive effects can be quite gross quantitatively. If one learns a list one day and tries to recall it the next, learns a second list and attempts recall for it the following day, learns a third and so on, recall for each successive list tends to decline. Roughly 80 percent recall may be anticipated for the first list; this declines steeply to about 20 percent for the tenth list. Learning the earlier lists seems to act forward in time (proactively) to inhibit retention of later lists. These proactive phenomena indicate that the more one learns the more rapidly one will forget. Similar effects can be demonstrated for retroactive inhibition within just one laboratory session.

Such powerful effects have led some to theorize that all forgetting is produced by interference. Any given memory is said to be subject to interference from others established earlier or subsequently. Interference, theoretically, may occur when memories conflict through any attributes. With a limited group of attributes and an enormous number of memories, it might seem that everyday attempts to recall would be chaotic.Yet even if all of the memories shared some information, other attributes not held in common could still serve to distinguish them. For example, every memory theoretically is encoded at a different time and temporal attributes might serve to discriminate otherwise conflicting memories. Indeed, when two apparently conflicting lists are learned several days apart, proactive inhibition is markedly reduced. Assuming memories to be multiple-encoded, interference theory need not predict utter confusion in remembering.
Sources of interference are most pervasive and should not be considered narrowly. For example, any memory seems to be established in specific surroundings or context, and subsequent efforts to remember tend to be less effective when the circumstances differ from the original. Alcoholics, when sober, tend to have trouble finding bottles they have hidden while intoxicated; when they drink again, the task is much easier. Some contexts also may be associated with other memories that interfere with whatever it is that one is trying to remember.

Each new memory tends to amalgamate information already in long-term storage. Encoding mechanisms invariably adapt or relate fresh data to information already present, to the point that what is coded may not be a direct representation of incoming stimuli. This is particularly apparent when input is relatively meaningless; the newly encoded memory comes to resemble those previously established (i.e., it accrues meaning). For example, a nonsense word such as LAJOR might be encoded as MAJOR.
To recall any nonsense word correctly requires that an appropriate decoding rule be a part of the memory; but coding rules are subject to forgetting (interference) in the same way that any attribute is. Qualitative changes in memory may result when the information presented does not allow precise decoding; thus, when one sees a drawing of a jagged figure that resembles a star he might encode it as a star, knowing full well that it is not perfect. Subsequent decoding in recall (or recognition) thus produces only an approximation of the original jagged figure; it may well be influenced by other equally imprecise decoding rules already stored. In like fashion, somewhat incoherent sentences may become more reasonable during encoding; they tend to be reproduced in memory tests more coherently. When the learner has trouble making sense of any new stimulus (when he cannot specify encoding and decoding rules with precision) the decoded memory tends to resemble previously established memories.

Although interference has attracted wide support as an account of forgetting, it must be placed in perspective. Interpretations that emphasize distinctions between short- and long-term memory and that posit control processes for handling information are potentially more comprehensive than is interference theory. Behavioral evidence for interference eventually may be explained within such systems.
In addition, a number of deductions from interference theory have not been well supported by experiment. The focus of difficulty lies in the hypothesis that interference from established memories is a major source of proactive inhibition. The laboratory subject is asked to learn tasks with attributes that have varying degrees of conflict with memories established in daily life. Theoretically, the more conflict, the greater the proactive interference to produce forgetting. Yet a number of experiments have failed to provide much support for this prediction.

Interference theory also fails to account for some pathological forms of forgetting. Repression as observed in psychiatric practice, for example, represents almost complete, highly selective forgetting, far beyond that anticipated by interference theorists. Attempts to study repression through laboratory procedures have failed to yield systematic data that could be used to test theoretical conclusions.

Correlates of rate of forgetting

Although forgetting normally is expected to begin as soon as practice ceases, at times an exception (known as reminiscence) has been reported. In reminiscence, memory seems to improve without practice; retention is even better if tested after a rest period than if tested immediately after learning trials stop. Observed only over periods of a few minutes, this elusive phenomenon produces very small improvements, and forgetting follows. Scores of studies designed to elicit reminiscence have failed to do so, yielding only evidence of forgetting. Reasons for the conflicting findings have not been identified.

Degree of learning

The degree of learning is found to be directly associated with the amount of practice. In a metaphoric sense, specific memory may be said to grow stronger and stronger as practice proceeds. Even after a task can be performed or recited perfectly, continued practice (sometimes called overlearning) increases the “strength” of the memory. The rate of forgetting is slower when the degree of learning is greater. If there were one universal prescription for resisting forgetting, it would be to learn to a very high level initially; results seem even better when learning trials are not bunched together. Practice trials may be given en masse in a single session or the same number of trials may be distributed in sessions held on different days. The interrupted schedule is far superior to massed practice in that the rate of forgetting that follows distributed practice is much slower. The laboratory evidence also confirms the belief that cramming for an examination may produce acceptable performance shortly afterwards, but that such massed study results in poor long-term retention. Information learned in widely distributed practice appears less susceptible to interference; memories established under distributed schedules also are less likely to produce proactive inhibition than are those learned in massed trials.
Mnemonic systems

The principle that new information is encoded to previously stored data has been used in an effort to aid memory function. When encoding techniques are formally applied, they are called mnemonic systems or devices. (The popular rhyme that begins “Thirty days hath September . . . ” is an example.) Verbal learning can be enhanced by providing an appropriate mnemonic system (even to a bright college student who may have devised efficient systems of his own). Thus, paired associates (e.g., DOG-CHAIR) will be learned more rapidly if they are included in a simple sentence (e.g., The dog jumped over the chair). Imagery that can relate different words to be learned (even in a bizarre fashion) has been found beneficial. Some investigators hold that pure rote learning (in which no use is made of established memories except to directly perceive the stimuli) is rare or nonexistent. They suggest that all learning elaborates on memories already available. This could be taken to mean that the rate of forgetting would be the same whether or not a formal mnemonic system were used in learning.

Indeed, there seem to be no experimental results in which formal mnemonic instruction has resulted in forgetting more rapidly than when such special training is not given. Yet, while there often is no difference in the rate of forgetting, a number of studies indicate slower forgetting following instruction in a mnemonic system. These discrepancies may mean that some mnemonic systems are more subject to interference than are others. Perhaps the methods used fail to adequately distinguish between learning and forgetting.

Factors that influence the rate of learning should be distinguished from those that affect the rate of forgetting. For example, nonsense syllables are learned more slowly than are an equal number of common words; if both are studied for the same length of time, the better learned common words will be forgotten more slowly. But this does not mean that rate of forgetting intrinsically differs for the two tasks. Degree of learning must be held constant before it may be judged whether there are differences in rate of forgetting. Rates of forgetting can be compared only if tasks are learned to an equivalent degree. Indeed, when degree of learning is experimentally controlled, different kinds of information are forgotten at about the same rate. Nonsense syllables are not forgotten more rapidly than are ordinary words. In general, factors that seem to produce wide differences in rate of learning show little (if any) effect on rate of forgetting. (Despite discrepant evidence, mnemonic systems may prove an exception.)

Individual differences

Experimental findings seem to contradict the common intuition that people inherently differ in the rate at which they forget. This intuitive belief appears largely to derive from definite, wide individual differences in rate of learning; some people do learn faster than others. Thus, given the same number of trials or identical time in which to study, people will vary widely in the level of learning they achieve. Individual differences in forgetting then can be predicted efficiently, merely on the basis of how well each person has learned. This powerfully indicates that ordinary estimates of one's rate of forgetting are spurious, being obscured by uncontrolled differences in learning ability. One's talent for learning seems to swamp efforts to assess his inherent tendency to forget. Under less ordinary circumstances, however (e.g., selective brain injury, stroke, neurotic amnesia), the degree of learning does seem to be almost completely irrelevant to the rate at which one forgets. An amnesia sufferer may forget his own name and still may be able to remember that Sofia is the capital of Bulgaria (see below Abnormalities of memory).

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