Mnemonics

Let's look a little deeper into the value of mnemonics for knowledge acquisition. By “knowledge acquisition”, I mean the sort of information you learn from textbooks — information that is not personal, that you need for the long-term.

In this context, I believe the chief value of mnemonic strategies is to help you recall information that needs to be remembered in a particular order. Thus we use mnemonics to help us remember the order of the planets, the order of musical notes on the stave, the order of the colors in a rainbow.

Sometimes we impose an order to make something easier to remember. Thus, HOMES is an established acronym to help people remember the Great Lakes of North America (Huron, Ontario, Michigan, Erie, Superior). The order of the lakes has no meaning, except that, ordered in such a way, the initial letters form a word.

Notice that, of course, the sole assistance this acronym offers is to serve as a reminder cue, by telling you the initial letters of the lakes (and how many there are). You have to already know the names of the lakes.

Other mnemonics for the Great Lakes provide slightly more information, by involving a meaningful order. Thus, “Sam's Horse Must Eat Oats” orders the lakes according to size, and “Sergeant Major Hates Eating Onions” tells you the order of the lakes from west to east.

None of these help you remember the actual names of the lakes.

You could use words similar in sound to the lakes’ names, to help in remembering the names. However, this may well result in a mnemonic that is harder to remember. For example, “Superior Mitch Again sees a Herons’ Eyrie Entire” makes far less sense and is a much harder sentence to remember than “Sergeant Major Hates Eating Onions”.

All this emphasizes the main point about mnemonics, a point that sometimes gets a little lost in the shuffle. Mnemonics are adjuncts to learning. They have their place, and they are extremely effective for their purpose, but you have to remember that their purpose is very limited. Thus, if you wished to learn the Periodic Table of Elements (a question about ways of memorizing the Periodic Table was actually what provoked this article), then you could simply devise a first-letter mnemonic for the table, such as:

He Helps Limping Beggars Borrow Crutches Nicely Or Fairly Near. Naturally Magazines Allow Simple Punctuation Should Clear Arguments. (the first 18 elements, i.e., the first three rows of the Table).

And of course, this won’t help you in any way if you are not already very familiar with the names of the elements. Nor will it tell you anything at all about the significance of the Periodic Table.

Why would you want to memorize the Periodic Table of Elements?

I don’t mean this question to indicate contempt for the task, I actually believe deeply in the value of having core information tamped down, as it were, deep into your knowledge base. You cannot develop any expertise in a subject without knowing the core facts — really knowing, in the same way you know your name and birthdate and, maybe, the names of the players in your favorite sports team, or the words to a favorite song, or the names of the characters in your favorite TV show. (Mnemonics do not, in fact, play a role when you have that depth of knowledge. Once you know something at the level of instant accessibility, you don’t need a mnemonic. But mnemonics can be of great help in the early stages of developing your knowledge.)

But let’s return to the question. Why do I ask it? Because, whenever you want to learn something, you should ask yourself why. Not in the spirit of “does it really matter?”, but with the purpose of establishing precisely your goal. Notice the word “precisely”. It’s not enough to simply say, “Well, I need to know the Periodic Table because I’m studying chemistry, and the teacher tells me I have to know it.” Why does your teacher insist you learn the Periodic Table? How does it help your understanding of chemistry?

The Great Lakes of North America are simply several large bodies of water in geographical proximity. Knowing their names is of no deep significance, has no larger meaning. The Periodic Table, however, does have larger meaning. The order of elements is no arbitrary thing, and the placement of an element in a particular place in the Table is deeply significant.

The Periodic Table arranges the elements in such a way as to demonstrate the pattern underlying the physical and chemical similarities between elements. If you know where an element is in the Table, you know a great deal about the element.

To know that, however, you must understand a great deal more about the Periodic Table than simply the order of the elements. The order of the elements tells you nothing in itself.

So, what is it that you really need to know? Not the order, as such. Not simply: Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminum Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton etc. The Periodic Table is a table for good reason, and you should never lose sight of that.

The rows have significance. The columns have significance. You don’t want to be able to say, “Oh, Scandium. That’s between Calcium and Titanium.” So?

More to the point would be if you knew Scandium was in row 4 and column 3B — that would tell you something (if you knew the significance of the rows and columns).

I’m not knocking the use of mnemonics to learn this sort of information. Mnemonics, used wisely, can facilitate your learning in the beginning. But, if the information you want to memorize has any meaning, you need to combine the use of mnemonic strategies with the use of strategies that are appropriate for meaningful learning. Never forget that the purpose of mnemonic strategies is to help with arbitrary information, facts that have no meaningful connection with each other.

Thus, to master the Periodic Table, you should look at the underlying principles and the meaningful clusters. Use mnemonics to memorize members of meaningful clusters, by all means. Just remember to clearly articulate precisely what you need to know (and then, redefine your goals at intervals as your knowledge grows), and organize the information in ways that support those precise goals. Then apply your mnemonics judiciously.

In the mid-seventies, Raugh and Atkinson had remarkable results using the keyword method to teach Russian vocabulary to college students. While later studies have not tended to find such dramatic results, nevertheless, a large number of studies have demonstrated an advantage in using the keyword mnemonic to learn vocabulary.

Some researchers have become huge fans of the strategy. Others have suggested a number of limitations. Let’s look at these.

Remembering for the long term

The keyword method is undeniably an effective method for accelerating learning of suitable material. Nor is there any doubt that it improves immediate recall. Which can be useful in itself. However, what people want is long-term recall, and it is there that the advantages of the keyword method are most contentious₁.

While many studies have found good remembering a week or two after learning using the keyword mnemonic, others have found that remembering is no better one or two weeks later whether people have used the keyword mnemonic or another strategy. Some have found it worse.

It has been suggested that, although the keyword may be a good retrieval cue initially, over time earlier associations may regain their strength and make it harder to retrieve the keyword image. This seems very reasonable to me — any keyword is, by its nature, an easily retrieved, familiar word; therefore, it will already have a host of associations. When you’re tested immediately after learning the keyword, this new link will of course be fresh in your mind, and easily retrieved. But as time goes on, and the advantage of recency is lost, what is there to make the new link stronger than the other, existing, links? Absolutely nothing — unless you strengthen it. How? By repetition.

Note that it is not the keyword itself that fails to be remembered. It is the image. The weakness then, is in the link between keyword and image. (For example, the Tagalog word araw, meaning sun, is given the keyword arrow; when tested, araw easily recalls the keyword arrow, but the image connecting arrow with sun is gone). This is the link you must strengthen.

The question of the relative forgetting curves of the keyword mnemonic and other learning strategies is chiefly a matter of theoretical interest — I don’t think any researcher would deny that repetition is always necessary. But the “magic” of the keyword mnemonic, as espoused by some mnemonic enthusiasts, downplays this necessity. For practical purposes, it is merely sufficient to remember that, for long-term learning, you must strengthen this link between keyword and image (or sentence) through repeated retrieval (but probably not nearly as often as the repetition needed to “fix” meaningless information that has no such mnemonic aid).

One final point should be made. If the material to be learned is mastered to the same standard, the durability of the memory — how long it is remembered for — will, it appears, be the same, regardless of the method used to learn it₂.

Are some keyword mnemonics easier to remember than others?

A number of factors may affect the strength of a keyword mnemonic. One that’s often suggested is whether or not the mnemonic is supplied to the student, or thought up by them. Intuitively, we feel that a mnemonic you’ve thought up yourself will be stronger than one that is given to you.

One study that compared the effectiveness of keywords provided versus keywords that are self-generated, found that participants who were required to make up their own keywords performed much worse than those who were given keywords₃. This doesn’t answer the question of the relative durability, but it does point to how much more difficult the task of generating keywords is. This has been confirmed in other studies.

The quality of the keyword mnemonic may affect its durability. Mnemonics that emphasize distinctiveness, that increase the vividness and concreteness of the word to be learned, are remembered less well over time than mnemonics that emphasize relational and semantic information (which is why the emphasis in recent times is on making interactive images or sentences, in which the keyword and definition interact in some way). Having bizarre images seems to help remembering immediately after learning (when there is a mix of bizarre and less unusual images), but doesn’t seem to help particularly over the long term.

The advantage of a semantic connection may be seen in the following example, taken from an experimental study₃. Students in a free control condition (those told to use their own methods to remember), almost all used a keyword-type technique to learn some items. Unlike those in the keyword group, the keywords chosen by these subjects typically had some semantic connection as well. (The use of somewhat arbitrary keywords is characteristic of the strategy as originally conceived by Atkinson). Thus, for the Spanish word pestana, meaning eyelash, several people used the phrase paste on as a link, reflecting an existing association (pasting on false eyelashes). The keyword supplied to the keyword group, on the other hand, was pest, which has no obvious connection to eyelash. (It is also worth noting that verbal links were more commonly used by control subjects, rather than mental images.)

It has been suggested that keywords that are semantically as well as acoustically related to the word to be learned might prove more durable.

Controlled presentation

For experimental reasons, the information to be learned is usually presented at a fixed rate, item by item. There is some suggestion that an unpaced situation, where people are simply presented with all the information to be learned and given a set time to study it, allows better learning, most particularly for the repetition strategy. The performance of rote repetition may have been made poorer by constraining it in this way in some experimental studies.

An unpaced study time is of course the more normal situation.

The importance of one-to-one instruction and the need for practice

What is clear from the research is that instruction in the technique is vitally important. Most particularly, the superiority of the keyword mnemonic tends to be found only when the students have been treated individually, not when they have been instructed as a group. At least, this is true for adults and adolescents, but not, interestingly, for children. Children can benefit from group instruction in the technique. Why this is, is not clear. However, I would speculate that it may have something to do with older students having already developed their own strategies and ideas. More individually-oriented instruction might be needed to counteract this depository of knowledge.

It might also be that children are given more direction in the using of the technique. That is, they are given the keywords; the images may be described to them, and even drawn. Clearly this is much simpler than being required to think up your own keywords, create your own links.

It does seem clear that durable keyword images require quite a lot of practice to create. It has been suggested that initially people tend to simply focus on creating distinctive images. It may only be with extensive practice that you become able to reliably create images that effectively integrate the relational qualities of the bits of information.

Some words benefit more from the keyword mnemonic

It has been suggested that the keyword mnemonic works effectively only on concrete words. For the most part, researchers only use concrete words (which are easily imageable). Studies which have compared the two are rare. The weight of the evidence is probably against the view that the mnemonic should be restricted to concrete words, but it may well be more difficult to come up with good, concrete images for abstract words. However, verbal mnemonics (a sentence can link the keyword with the definition) don’t suffer the same drawback.

In experimental studies, the words are usually vetted to make sure they’re not “easy” to learn because of obvious acoustic or graphic similarities with familiar words. The implication of this for real world learning, is that there is no reason to think that such words require a keyword mnemonic.

How important is the image?

Most research has focused on using an image to link the keyword with the definition. One study which compared the using of an image with the use of a sentence (in a study of children’s learning of Spanish words) found no difference (the sentence mnemonic in fact scored higher, but the difference was not significant)₄.

Is the keyword mnemonic of greater benefit to less able students?

Several researchers have suggested that the keyword mnemonic might be of greater benefit to less able students, that the keyword mnemonic may be a means by which differences in learning ability might be equalised. One study that failed to find any superiority in the keyword mnemonic among college students, pointed to the high SAT scores of their students. They suggested that those studies which have found a keyword superiority using college students, have used students who were less verbally able₅.

What seems likely, is that teaching the keyword mnemonic to more able students has less impact than teaching it to less able students, because the more able students already have a variety of effective strategies that they use. It is worth noting that, just because students are instructed to use a particular strategy, that doesn’t mean that they will. In one experimental study, for example, when subjects were asked about the strategies they used, 17 out of the 40 control subjects (instructed to use their own methods) used the keyword method for at least some items, while every keyword subject used the keyword method for at least seven items (implying they didn’t always). In that study, it was found that, for the control subjects, the probability of recalling keyword-elaborated items was .81 vs .45 for other items; while for the keyword group, the probability of recall for keyword-elaborated items was .80 vs .16 for those items for which they didn’t use a keyword mnemonic₆.

Comparing the keyword mnemonic to other strategies

As a general rule, experimental studies into the effectiveness of the keyword mnemonic have compared it to, most often, rote repetition, or, less often, “trying your hardest to remember” (i.e., your own methods). It is not overwhelmingly surprising that the keyword mnemonic should be superior to rote repetition, and the study quoted just above reveals why comparisons with “free” controls might show inconsistent (and uninformative) results.

Studies which have directly compared the keyword method to other elaborative strategies are more helpful.

A number of studies have compared the keyword strategy against the context method of learning vocabulary (much loved by teachers; students experience the word to be learned in several different meaningful contexts). Theory suggests that the context method should encourage multiple connections to the target word, and is thus expected to be a highly effective strategy. However, the studies have found that the keyword method produces better learning than the context method.

It has been suggested that students might benefit more from the context method if they had to work out the meaning of the word themselves, from the context. However, a study which explored this possibility, found that participants using the context method performed significantly worse than those using the keyword mnemonic₅. This was true even when subjects were given a test that would be thought to give an advantage to the context method — namely, subjects being required to produce meaningful sentences with the target words.

The same researchers later pursued the possibility that the context method might, nevertheless, prove superior in long-term recall — benefiting from the multiple connections / retrieval paths to the target word. In an experiment where both keyword and context groups learned the words until they had mastered them, recall was no better for the context group than it was for the keyword group, when tested one week later (on the other hand, it was no worse either)₂.

Two more recent studies have confirmed the superiority of the keyword mnemonic over the context method₇.

Another study looked at the question of whether a combined keyword – repetition strategy (in which subjects were told to use repetition as well as imagery when linking the keyword to the English translation of the word to be learned) was better than the keyword strategy on its own. They failed to find any benefit to using repetition on top of the imagery₈.

Given the procedures used, I can see why this might occur. Imagine you’re trying to learn that carta is Spanish for letter. The obvious keyword is cart. Accordingly, you form an image of a cart full of letters. However, having constructed this image, you are now told to repeat the salient words “carta - letter” over and over to yourself. It’s not hard to see that many people might completely lose track of the image while they are doing this. Thus the repetition component of the strategy would not be so much augmenting the imagery link, as replacing it. Repetition of the link you are supposed to be augmenting (a cart full of letters) might be more useful (in fact, I personally would repeat to myself: “carta – letter; a cart full of letters”).

Backward recall

The value of the keyword mnemonic is of course, in forward recall — that is, in the above example, you learned that carta meant letter. When you see the word carta, the keyword mnemonic will help you remember that it means letter. But if you are asked for the Spanish for letter, how helpful will the keyword mnemonic be then?

A study that looked at this question found that the keyword mnemonic was no worse for backward recall than the other strategies they employed₈. On the other hand, it was no better, either — and this despite being superior for forward recall (remembering the English when given the Spanish). The failure of the method was not due to any difficulty in recalling the keyword itself. Remember, the English meaning and the keyword are tied together in the mnemonic image, so it is not surprising that remembering the keyword given the English was as high as remembering the English given the keyword. But the problem is, of course, that generating the (unfamiliar) Spanish word from the keyword is much harder than remembering the (familiar) keyword from the Spanish.

Using the keyword mnemonic to remember gender

One other aspect of vocabulary learning for many languages is that of gender. The keyword mnemonic has successfully been used to remember the gender of nouns, by incorporating a gender tag in the image₉. This may be as simple as including a man or a woman (or some particular object, when the language also contains a neutral gender), or you could use some other code — for example, if learning German, you could use the image of a deer for the masculine gender.

Why should the keyword mnemonic be an effective strategy?

Let’s think about the basic principles of how memory works.

The strength of memory codes, and thus the ease with which they can be found, is a function largely of repetition. Quite simply, the more often you experience something (a word, an event, a person, whatever), the stronger and more easily recalled your memory for that thing will be.

This is why the most basic memory strategy — the simplest, and the first learned — is rote repetition.

Repetition is how we hold items in working memory, that is, “in mind”. When we are told a phone number and have to remember it long enough to either dial it or write it down, most of us repeat it frantically.

Spaced repetition — repetition at intervals of time — is how we cement most of our memory codes in our long-term memory store. If you make no deliberate attempt to learn a phone number, yet use it often, you will inevitably come to know it (how many repetitions that will take is a matter of individual variability).

But most of us come to realize that repetition is not, on its own, the most effective strategy, and when we deliberately wish to learn something, we generally incorporate other, more elaborative, strategies.

Why do we do that? If memory codes are strengthened by repetition, why isn’t it enough to simply repeat?

Well, it is. Repetition IS enough. But it’s boring. That’s point one.

Point two is that making memory codes more easily found (which is after all the point of the exercise) is not solely achieved by making the memory codes stronger. Also important is making lots of connections. Memory codes are held in a network. We find a particular one by following a trail of linked codes. Clearly, the more trails lead to the code you’re looking for, the more likely you are to find it.

Elaborative strategies — mnemonic strategies, organizational strategies — work on this aspect. They are designed to increase the number of links (connections) a memory code has. Thus, when we note that lamprey is an “eel-like aquatic vertebrate with sucker mouth”, we will probably make links with eels, with fish, with the sea. If we recall that Henry I was said to have died from a surfeit of lampreys, we have made another link. Which in turn might bring in yet another link, that Ngaio Marsh once wrote a mystery entitled “A surfeit of lampreys”. And if you’ve read the book, this will be a good link, being itself rich in links. (As the earlier link would be if you happen to be knowledgeable about Henry I).

On the other hand, in the absence of any knowledge about lampreys, you could have made a mnemonic link with the word “lamp”, and imagined an eel-like fish with lamps in its eyes, or balanced on its head.

So, both types of elaborative strategy have the same goal — to increase the number of connections. But mnemonic links are weaker in the sense that they are arbitrary. Their value comes in those circumstances when either you lack the knowledge to make meaningful connections, or there is in fact no meaningful connection to be made (this is why mnemonics are so popular for vocabulary learning, and for the learning of lists and other ordered information).

Where does that leave us?

• Memory codes are made stronger by repetition
• Repetition is enough on it’s own to make a strong memory code
• Achieving enough repetitions, however, is a lengthy and often boring process
• Memory codes are also made easier to find by increasing the number of links they have to other memory codes
• Elaborative strategies work on this principle of making connections with existing codes
• Some elaborative strategies make meaningful connections between memory codes — these are stronger
• Mnemonic strategies make connections that are not meaningful
• Mnemonic strategies are most useful in situations where there are no meaningful connections to be made, or you lack the knowledge to make meaningful connections

Mnemonic strategies have therefore had particular success in the learning of other languages. However, if you can make a meaningful connection, that will be more effective. For example, in Spanish the word surgir means to appear, spout, arise. If you connect this to the word surge, from the Latin surgere, to rise, then you have a meaningful connection, and you won’t, it is clear, have much trouble when you come across the word. However, if your English vocabulary does not include the word surge, you might make instead a mnemonic connection, such as surgir sounds like sugar, so you make a mental image involving spouting sugar. Now, imagine each of these situations. Imagine you don’t come across the word again for a month. When you do, which of these connections is more likely to bring forth the correct meaning?

But of course, it is not always possible to make meaningful connections.

The thing to remember however, is that you haven’t overcome the need for repetition. These strategies are adjuncts. The basic principle must always be remembered: Memory codes are made stronger by repetition. Links are made stronger by repetition. If you don’t practice the mnemonic, it won’t be remembered. The same is true for any connection, but meaningful connections are inherently stronger, so they don’t need as many repetitions.

I would also note that the experimental research invariably involves very limited numbers of words to be learned. While this is entirely understandable, it does raise the question of the extent to which these findings are applicable to real world learning situations. If you are learning a new language, you are going to have to learn at least 2000 new words. Does the keyword mnemonic hold up in those circumstances? The keyword mnemonic has been used in real world situations (intensive language courses), but these are not experimental situations, and we must be wary of the conclusions we draw from them. The keyword strategy does take time and effort to implement, and may well have disadvantages if used to excess. Some words lend themselves to other techniques. At least for more experienced students (who will have a number of effective strategies, and are capable of applying them appropriately) the keyword strategy is probably best used selectively, perhaps for particularly difficult items.

In 2002, a British study scanned the brains of ten "superior memorizers" — eight leading contenders in the World Memory Championships, and two individuals previously studied for their extraordinary memory accomplishments — all people that had demonstrated truly impressive feats of memory, in terms of the ability to quickly memorize hundreds of numbers or unrelated words. The ten "memory champions" were matched with ten controls, who had no memory capabilities out of the ordinary.

Testing revealed that the memory champs scored about the same as the controls on general cognitive ability, but did, unsurprisingly, score higher on working memory and long-term verbal memory. They didn't differ in visual memory.

Participants in the study were shown three sets of images; faces, snowflakes and three-digit numbers. The numbers, being the sort of items which the memory champs excel at, were expected to show large performance differences between the two groups. Faces are a class of stimuli for which most people have a considerable expertise in, so a smaller difference was expected. And snowflakes are a very difficult visual pattern to verbalize, and it was expected that both groups would be equally poor at remembering them.

Their brains were scanned while the participants were asked them to remember which ones they had seen, and the order they were shown in. The expected differences in performance were indeed found, allowing the researchers to differentiate between brain activity that reflected the learning prowess itself from the activity reflecting the amount of information learned.

A number of brain regions were of course active in all tasks, for both groups. But there were differences between the two groups, both in terms of greater activity in some regions, and, more interestingly, in terms of the memory champs using brain regions not used by the controls. Most particularly, regardless of task and regardless of performance, the memory champs engaged the left medial superior parietal gyrus, bilateral retrosplenial cortex, and right posterior hippocampus. These areas are all known to be involved in spatial memory and navigation.

On questioning, nine out of ten memory champions advised that they used the loci mnemonic for some or all of the tasks.

The researcher concluded, "Superior memory was not driven by exceptional intellectual ability or structural brain differences. Rather, we found that superior memorizers used a spatial learning strategy, engaging brain regions such as the hippocampus which are critical for memory and for spatial memory in particular."

As another researcher commented, "If you use the right technique, with a lot of application and hard work you can improve your memory. It certainly doesn't look like it's a question of neurological machinery."

The most interesting finding from this study was that, among the memory champs, there were no changes in gray matter volume, despite the fact that these people had been practicing mnemonics for an average of 11 years (a range of 3 to 38.5). Similar brain scans of musicians and London taxi drivers have found significant increases in gray matter volume as a function of number of years practice/experience. This finding would seem to support the view that practice in rote learning strategies doesn't have the benefits of strategies that develop understanding and mastery of meaningful knowledge, in terms of building new connections and growing new neurons.

On that note, you might like to read my article on photographic memory (and whether it's really as desirable as all that.)

Retrieval practice, as its name suggests, is a simple strategy that involves retrieving the target information one or more times prior to testing. It is not the same as repetition or rehearsal! The idea is not to simply repeat the correct information, but to try and retrieve it. Feedback as to the correct answer may or may not follow.

The keyword mnemonic is the most studied mnemonic strategy, and of proven effectiveness in learning vocabulary, most particularly when measured against rote repetition or “use your own methods”, but also when compared with the popular context method (students experience the word to be learned in several different meaningful contexts; they may or may not have to guess the meaning from the context). It has also effectively been used to learn artists’ styles, taxonomic information, attribute information, and the main points in text passages.

Results from using the keyword method have been quite dramatic. For example, in a classic study from the researchers that developed this strategy (Atkinson & Raugh 1975), over a third of the 120 words were remembered more than 80% of the time in the keyword condition, compared to only one item in the control condition (glaz for eye — a mnemonic link so obvious I am sure most of the control participants used it). Moreover, only seven words were remembered less than half the time in the keyword condition, compared to 70 in the control (“use your own method”) condition! Overall, the keyword group recalled 72% of the words when they were tested on the day following the three study days (40 words were studied each day), compared to 46% by the control group. When they were (without warning) tested again six weeks later, the keyword group remembered 43% compared to the control group’s 28%.

As you see, the benefits of the method are quite clear.

Which demonstrates how impressive it is that in a study that compared the two, retrieval practice resulted in the same, and in some cases, better performance than the keyword method.

In this 2007 study¹, two lab experiments involving university students compared the learning of German words using either the keyword mnemonic, retrieval practice, or rote repetition, and found no difference in performance between the two experimental groups, and both significantly better than rote repetition. This was followed by an experiment involving 56 secondary school pupils, comparing the learning of German words learned in four different ways (that is, all the pupils were given the same instruction; groups of words were presented in different ways).

In the first section of the instruction booklet, each English word with its German translation was presented with an elaborating sentence (for example, “The German for SHARP is SCHARF, scharf also means hot (as in spicy).”; “The German for LIGHTHOUSE is LEUCHTTURM, Leuchtturm consists of the two words for shine and tower.”) — this was the elaboration strategy. In the next section (retrieval practice), the English and German words were read out when first presented, and on the following pages the students were required to retrieve the German word on seeing the English word. There were filler pages in between each retrieval attempt on the expanding schedule of 1-3-5-7 (that is, one intervening filler item before the first attempt, three items before the second attempt, and so on). In the third, keyword, section, the English and German words were presented with a description of a suggested image (e.g., “The German for SHARP is SCHARF. Imagine cutting a German flag with SHARP scissors.” “The German for LIGHTHOUSE is LEUCHTTURM. Imagine people LOITERING near a lighthouse.”). In the last section, a strategy combining both the keyword and retrieval practice was employed.

The time allowed for each page was controlled, and was only a few seconds.

There were two tests: recalling the English meaning on seeing the German words, and giving the German words when presented with the English meaning. The tests were given twice — immediately, and one week later. For the easier task (giving the English in response to the German), words learned using the elaboration strategy were significantly more poorly remembered, and results from the other three strategies were not significantly different in the immediate test, but after a week, the words learned by the combined method were significantly better remembered than those learned by the others. Words learned by the retrieval practice strategy were slightly, but not quite significantly, better remembered than those learned by the keyword method.

For the harder task (remembering the German), the difference between retrieval practice and keyword mnemonic reached statistical significance.

The big advantage of retrieval practice is of course that it is a very simple, easily learned technique. It also requires much less cognitive effort than the keyword mnemonic, which puts off many people because of the difficulty of finding good keywords, and the effort (which is greater for some than for others) of creating images.

There are two aspects of the retrieval practice strategy, as it was used here, that should be noted. One is the basic principle that retrieval is always better than rehearsal, because retrieval is the task you should be practicing for, and because rehearsal gives you no feedback as to how well you have learned, and retrieval does. That is why testing is so valuable — more valuable as a learning tool than as an assessment tool. Testing teaches; even pretesting (before the student even knows the information to be learned) improves learning. (Two studies on this are reported in a Scientific American article at https://www.scientificamerican.com/article.cfm?id=getting-it-wrong )

The second aspect is that the retrieval occurred on a distributed schedule.

I have talked before about the importance of spacing your learning (rehearsal; practice). So now I’ll just add one thing, from a recent (2009) study².

Interleaving practice is a related strategy that has (mostly in the area of motor skills, but of wider applicability) been shown to improve learning. With interleaved practice, a lesson is followed by practice problems relating to many earlier lessons, ordered so that no consecutive problems are of the same type. As is readily apparent, interleaving naturally involves distributed practice, so it’s not clear whether interleaving is on its own, separate from the effects of distribution, of benefit. This new study managed to disentangle interleaving from spacing, and found that, even when spacing was held constant, interleaving more than doubled test scores (77% vs 38%).

However, and this is perhaps the really interesting part, it did so having impaired performance during practice. That is, not unexpectedly, performance was poorer during the learning period, when practice was interleaved.

And here we bring in a concept that is also of relevance in discussing the value of testing for learning: the idea of desirable difficulty (a term devised by Robert Bjork and colleagues).

In these days of trying not damage students’ self-esteem by having them experience failure, it is well to remember this concept.

(I have summarized this material in a 7-minute video.)