Memory training: what types of memory are there?

The first type of memory is our very short lived and very fragile sensory store (Short Information Store, SIS). It is the afterimage when seeing something, it is the aftersound when hearing something, it stays in your mind for just a couple of seconds at the most.

A second type of our storage system is our Working Memory (WM). It used to be called Short Term Memory (STM). It lasts for only a couple of seconds to roughly a minute. It is also fragile and it can roughly store 7 ± 2 units of information, whether that is a word, a sound, numbers or images. On my page about Attention: what is it I will explain why this Working Memory actually is Attention. The description 'Working' refers to the fact that this is the short term storage where information is being worked on in order to store it more permanently in our Long Term Store (LTM).Very important to remember is that this WM capacity is NOT fixed: it changes every second due to our bio-dynamical brain system.

Our third type of storage is the Long Term Memory (LTM): it can last for years and its capacity seems unlimited (in reality it is nót unlimited of course). It takes hours till a couple of days to form a reliable LTM of something and that is largely a biochemical process called Long term potentiation or the Consolidation process. Usually, repeating the same information several times and having nights of sleep between repetitions is most desirable to form solid LTM.

For a schematic of these fundamental types of storage see this Figure:

The types of information that are stored in our brain is categorized as well in the scientific literature. The first information storage takes place as our senses pick up this information, either visually or auditorily. This information is strongly related to a specific time, place and other specific details. It is stored as a sort of episode, so science calls this kind of storage: episodic memory. It consists of lots of facts in all modalities (being visual, auditory, tactile, smell). When a lot of such factual information is stored in your brain, sort of piled up, your brain starts to categorize it and subtracts out of it more abstract information. This kind of more abstract information (not related specifically to any specific time or place) is placed in a so-called 'semantic' store. It is the kind of information like 'birds have feathers and can fly'. No specific bird is meant but all the experiences with birds are summarized in a more abstract form.

Another kind of information storage is information that is much more difficult to describe in words: 'procedural' memory. It is not the 'what' kind of information but more the 'how'-kind. Like when you learn to ride a bike, or learn to play tennis. It is more the movement kind of storage. The brain stores essential parts of a movement or activity to repeat such activities on a later date. We consciously do not know exactly whát is stored, but we clearly notice that something must be stored because we see that we have learned some things.

More unconscious storage of information is 'classical conditioning' and 'operant conditioning'. These processes are rather quickly and usually unconsciously formed. Classical conditioning is the bonding between two stimuli or events, normally unrelated to each other. When for example seeing a big rat in your house, totally unexpected, in the kitchen near the trash can just as you open the trash bin, an association is made between the bin and the rat. Next time you want to open the bin, your anxiety level is raised automatically because of this incident with the rat.

Operant conditioning refers to the relation formed between some kind of behavior and its consequences. For example, when pressing on a lever in a box, a rat discovers he gets some food. The relation between his behavior (pressing on a lever) and that food is then strengthened and formed in his LTM.

The fundamentals of memory training

Now that you know the main types of memory it is time to mention the most essential parts of its training. There are dozens of books and a lot of scientific literature about this kind of training and I have read many. However, my experience with more than 2000 brain injury patients has helped me a lot more to see how and when memory training is effective. I want to share this knowledge with you so you do not need to read all those books. But most of all, I will tell what is not in those books, I can and will tell you about the pros and cons of such training in real life. Especially, I will focus on such training after brain injury because that is quite different from training with a healthy brain.

First of all, memory training relies on a few fundamental principles: Attention, Time, Repetition, and Associating (ATRA).

Every information you want to remember has to be attended to. That is, more or less consciously processed: you have to be aware of it. Without such attention you will not remember it (correctly). This is also the main reason why people forget names so easily when they meet each other and are introduced to each other. They simply do not pay enough attention to the new name. To put it in other words: it has to be in Working Memory for a time long enough to start the consolidation process in LTM.

very closely related to Attention is time: spending enough time with the information to be remembered. Simply just hearing a name and not spending any time on it will not help you to remember it for a long time. This is what you will learn in any type of training: it will take a lot of time to learn tips and tricks and it takes time to remember something reliably. Time has a lot to do with how many processes are selected to work on the information to be stored.

of course, repetition increases the time and attention to the item you want to remember. And it has no use to repeat it over and over again, just in as less time as possible. Science now knows you have to spread your repetitions over days, with some sleep in between. That is the best way to store the information in your LTM. Training courses itself use repetition of their information to remember the lessons well.

But the most fundamental part of storing information in our LTM is associating this information to the information we already know. It is exactly HOW we couple or associate new information to our knowledge, that determines how well we will store and remember it. That is the reason most training courses pay so much attention to the methods to store something in our LTM.

Several methods used are visualization: trying to form images of the information to remember. Usually we remember images much better than verbal information so this method tries to train associations based on images. Other methods use localization (trying to imagine information stored in specific places, well-known to you), or weirdness (making the information associated with very strange ideas or images).

All these training methods just try to hook new information onto old known information in LTM. Essential in this process is the ability to order and categorize all information. When a book is brought back to the library, the librarian knows exactly where it has to be put, to be found again. Imagine, a book on history is put back between books about sex...that would result in not finding this book again...between 100.000 books. The precise process of categorization has to be logical, consequent and clear to ever find information back in your brain storage systems. 

Examples of how to remember common things in daily life

The most common problems in daily life are remembering peoples' names. That is usually not caused by your poor memory but by your poor learning habits: You just don't attend to or spend enough time to the name you hear. You have at least to repeat this name once, preferably aloud. Then you have to try to relate this name to something extraordinary which is an attribute of that person. You have to think of an association that triggers some kind of feature of that person (e.g. his big nose, sharp pointed ears) that you certainly will remember. I myself, just use some information of what that person has done in his life, usually his career, and relate this information to his name. When trying to remember his name or face, I just have to bring back the story of how he became a carpenter and almost immediately his face and name pop up. Of course, everyone has its own style of learning. Some remember a name or face by focusing on some physical features of that person, others remember much better when they think of someone's birth place or even date. There are good books in which more nice methods are explained.

Whether you want to remember telephone numbers or codes for your bank account or card, you have to associate each number to something very familiar to yourself. Several methods are found in books: relating a number to the first letter of a word (e.g. 8, eight, becomes 'eat'), making up some relation between the numbers (like, 1785, becomes 1+7=8, high five!). Make a sequence of numbers special to you and keep it simple. What usually helps is to chunk: divide a long number into smaller parts (chunks) and associate each part with a word or image. However, trying to remember such numbers in such a way takes some time, perhaps even 10 to 15 minutes. When it is an important number, like your credit card, than this time investment can be worthwhile. When you do not have to remember a number for very long, just write it down.

Everyone shops and has to remember what has to be bought. Normally, just write a short shopping list. Why investing 10 to 15 minutes to remember some things that you will only forget because it is no use storing them?When you really want to impress your wife or others by remembering a shopping list, try imagining the shop where you will go and locate all items you want. When it is a familiar shop with steady locations of each item, this will work astonishingly well. You can also associate each item with a short story in which this item plays a major role. When you want to make pasta with a tomato sauce, it really helps to imagine the process of pasta making and what you'll have to do.

Well, to be honest, just write them on a calendar you'll check every morning or evening. I'll bet this is not something you will read in a book. It is very difficult to remember appointments by heart, unless there are only a few. Normally, you can remember them by vividly imagining the appointment and what you want out of this appointment. Just going through this appointment in your mind (and visualizing it) really helps a lot to remember it in the very next week. Do NOT try to remember an appointment when it is due over 2 or 3 weeks. That makes not much sense. Just write them down on a calendar and get used to looking every morning or evening at a same specified time to this calendar. Another simple option is to get reminded by using a mobile phone alarm or a smartphone or PDA. Of course you can try some training tips in books you have read but really, when having a lot of appointments, why not just make your life much easier and try focusing on what is really important (like, preparing an appointment and making the other quite comfortable)?

Too much value is placed on remembering trivial things or events that happened. What's the point of remembering everything that happened yesterday? You will never succeed in this effort, neither does it help you very much. I've had patients who just recorded every conversation they had, in fear of forgetting it. However, they turned up in having tons of MP3 or WAV-files on their computer or PDA/smartphone. Really nice, flawless memory, until they realized that just listening to all those recordings took at least as long as the time it took to make those recordings! So, that was time spent pointlessly and they stopped living a normal life! When you really want to remember precious and important things, events, happenings, please make photos, videos and store them safely on your hard disk and code this logically with a time stamp and theme-label (e.g. May 2010: birthday of Peter).For what's worth: do NOT bother too much about forgetting things in the past. It really ruins your quality of life, increases your anxiety.Again, you won't find this sort of advice in memory training courses. That is due to a common misconception that our lives should be like products which can be manufactured and mended. Nice idea, but given some thought, this is not really true.

The same advice as given above is valid here: do you really want to remember everything you see or hear on television? Impossible...and useless. When you really want to remember relevant information for yourself, please make a summary, a mind map, a short story in which this information is placed and store this on your computer. Patients with memory problems complain that they don't remember the pages in a book that they are reading. When there are several days in between reading, they forget the characters or the storyboard. Of course, that is not really helping to enjoy the long story in the book. There is no simple solution to this problem. Either, you make some summary of what you have read and re-read it every time you start picking up this book, or you just go ahead and read the book where you were. Normally, most patients do not want to bother to invest a lot of time to make a summary of the book chapters. They start to realize that just thát reduces the quality of reading a book. That is the moment when they start to read more simple books or shorter books in which the storyline is much more clear. Not really a solution you might think? Well, in fact it is. It prevents them from not reading any book anymore and it still gives them the nice feeling of reading. This kind of training is called 'compensatory memory training'.

Usually, with memory problems, someone can repeat a question or story over and over again, much to the annoyance of the partner. My daughters even say to me quite frequently that 'I have mentioned that a few times before'. There is not much we can do about this, unfortunately. You can not write down all stories you tell or questions you ask. It would not be very practical in daily life to carry around a notepad in which you first have to search what you have told or asked already. That is why my advice in these cases is, again, very simple: please agree with each other on a sign that the partner can give when you have already asked or told something. It can be a simple touch on your arm with a loving tender face and the words: 'darling, you've told me..." This really helps to let it rest and not get irritated. It keeps the relationship going and healthy, despite serious memory problems. It is very important to agree both upon this kind of action and to write it down visibly so to remind your partner. I have never seen any serious attempt in memory training books to get this problem solved. Probably, because there just is no real solution.

The so-called 'tip-of-the-tongue' phenomenon occurs in everyone and increases with advancing age. Everyone who is telling some story knows that they sometimes can not remember a word or concept immediately when they want to. There is no point in getting irritated about this. It only worsens your problem. Just continue with your story or think of something else. Let your unconscious mind do the work: it just might come up with the right words in a few minutes. Another tip is just to describe what you really want to say: when using more words and especially more images or activities related to the words you are searching for, the chances will increase that your brain comes up with just the right words. Do NOT get stuck on these words you're looking for. It only gets you into a loop you won't come out again!

You know the situation: you start walking towards the kitchen and on arriving you have forgotten what you intended to do there. This happens all the time to any of us, especially with advancing age. Don't get irritated but just go back to where you came from. When you start doing this walk again, normally your brain will be sort of 'reset' and your intentions will pop up again. That's due to the fact that any intention is temporarily associated with just the things you are doing right now. Including your surroundings: what you see, hear and smell. Confronted with the exact same surroundings again (by walking back and starting again), usually brings back your intentions. 

Again: how does your memory function really?

There are lots of things that are not yet clear about the functioning of the human memory system. However, several interesting models have been developed by different scientists. Below I will try to summarize these different models in a language you can understand as well. In this attempt I will give several examples from daily life to make some things clear. If necessary I will refer to good informative websites about memory processes.

Process nr 1: The uptake and storage of new information

As far as science knows everything starts with attending to information that comes towards us. That can be of a visual nature (images), auditory (sounds) or touchable (tactile). Not many people know that our brain can use all 5 sensory channels at the same time to store information (seeing, hearing, smelling, tasting, touching). In storing a nice face of a pretty girl you once have met at your dancing lessons, pretty much everything around her will be stored by your brain. Her voice (auditory), her face with the beautiful eyes (visual), her smell or special perfume that you still can remember, her soft hands (touch), but also the ball room in which you were dancing together, the colors of the floor there, and possibly some music that was playing when you danced with her. All that is stored together with that girl.

In this directory about ‘that girl’, residing somewhere in your Long Term Memory (LTM), you will find all that extra information. That is possible because at the time of storing all this, your working memory (WM) was stuffed with all this kind of information. Within this WM all associations, all relations are made. The longer information units are held in WM, the more such relations between these information units are strengthened. This explains pretty much why that perfume is still being remembered by you: it was constantly in your WM, together with other information. When she talked to you with her lovely voice, when she touched you, when you went through certain steps with her, all this kind of information was coupled with that perfume that always was around and IN your WM. No wonder that when smelling that kind of perfume you will get immediately flashbacks of those dancing days and that girl. But another special thing is going on with a scent: it is extremely related to emotions. A nice perfume is strongly related to feelings of happiness, being in love and sexual feelings. Your brain is on high (sexual) alert when smelling nice perfumes. Everything that is related to this perfume odour will be remembered extraordinary well. Just as a very gentle touch of her soft hands can be remembered at least as well. 

It is, by the way, a misunderstanding to think that everything in your WM should be completely conscious. I seemed to suggest that in earlier texts but what I meant is that an important part of your WM is indeed conscious, but another part is not. Concepts like classical conditioning or operant conditioning are referring to more unconscious associations between information units. Unconscious meaning that you really do not know this, are not aware of this. However, if unconsciously associated with each other, this kind of information will not always be remembered actively. Therefore it is wiser to associate information on a more conscious level, to remember it better. Probably this is so because when consciously processing information we have the freedom of hów we associate things with each other. We have more to say about hów things are sequenced in our LTM. This kind of order can make us remember even more information than normal.

An example of conscious processing or sequencing of information is given here, to show it works much better than just relying on automatic brain processes. We have a memory test, for example the Rey Verbal Learning Test, in which we have to remember 15 normal words. For example: fire, house, leg, cow, milk, bank, money, liquid, blood, carpet (not all 15 words, I know). In hearing these words the first 5 or 6 words are put in your WM. Most people can remember these with no trouble at all. Because your WM is not overloaded yet and these words are automatically repeated in the phonological loop. So far so good: nothing special has to be done to remember all these words.

However, when hearing the rest of the 15 words after having heard 6 or 7, the capacity of your WM is limited and getting overloaded. Some words must fall out of this WM. Usually the first 3 or 4 words will be staying in WM due to the repetition loop. But the middle words will keep disappearing out of your WM. The last 3 or 4 words will be in your WM as well, due to the so-called ‘recency effect’. They will not be pushed out of it by other words (because no other words will follow). Remembering the first 3-4 words is called the ‘primacy effect’: these words were kept a little bit longer in your WM and so are stored a bit better than the middle words. When confronted with such a 15-word test for the first time, usually healthy people can remember 6 or 7 words, just as much as can be stored in WM at the same time.

Scientists know that memory storage works even better when you spread your new information. In other words: it has no use to repeat new information 30 times in 1 day. Of course, repetition is good but you have to do it more wisely: e.g. 3 times in 1 hour. Next do something different, take a long break, go running and later in the evening you repeat this information again 2 or 3 times. It is also wise to get a good night sleep in between learning. In your sleep, your brain starts to reshuffle and re-order all new information. Furthermore, chemically the strengthening of new synaptic associations (bridges between nerve endings) takes about 6-8 hours. After a night’s sleep, repeating the new information again for 2 or 3 times is wise as well.

Memory storage has to be varied as well. That has a lot to do with memory cues. When actively remembering things, you do need a lot of cues which are ideally all related to the information you want to remember. The chances of successfully remembering something are much higher when it is associated with a lot of other information. So: when learning something do make sure you consciously associate it with several different other information. Remember someone’s name not just by relating it to his face, but also relating it to his job, his income, his family, his hobbies you share with him, his interests. 

The figure above shows what happens when you use an automatic learning process or a more conscious and deliberate strategy to store new information. It is about the example of trying to remember more than 6 words, just like with a 15-word test. The better your learning strategy is, the more words you will store and remember. It is also a nice test of how well your so-called executive functions have been developed. These highest of the cognitive functions are taken care of by your frontal lobes (left and right). You can read more about these functions on my page on Problem solving deficits. It is possible to remember more words with just repeating the words, because in your WM more associations will be made between the words that are staying there for a longer time. Whenever you hear the word COW it can be that other associations pop up like grass land, milk, farm. Such associations are made automatically, more or less unconsciously. The chance that you will remember the words better is higher whenever more associations have been formed. However, just repeating is not enough. You have to do much better than that to remember so many words.

This example in remembering a lot of words when they are presented right after another already shows why the use of strategies is so difficult. You have to have some knowledge, be very flexible and you have to think creatively. You have to have skills to implement the correct strategies as well. Especially putting some order in the information and associating are very important. I myself am very visually oriented so that I can imagine very quickly several images to words. For me it is rather easy to imagine a COW with MILK and a broken LEG. The use of the Visualization strategy has to be very fast because the words are presented quickly as well. A high information processing speed and full concentration is necessary. If you are mentally slow a lot of strategies will not work.

This story about the memory storage process is not the whole story though. More factors are involved in storage: 1. a good working and sufficiently large WM; 2. a sufficient concentration; 3. a sufficient divided attention; 4. a sufficient associative ability; 5. a sufficient comprehension of language and a large vocabulary; 6. a sufficient flexible and creative ability; 7. a sufficient planning and logical reasoning ability. Also physiological factors play an important role. Especially what I have called the memory glue is important: the strength with which nerve cells can be coupled to each other. In one person this is biologically slower than in another person. That depends largely on the biochemistry in your brain, the quality of the “glue”. Some people only need 1 or 2 associations between 2 words and they’ll never forgot these bondings. That can be genetically determined or a result of years of training. Here I suspect that having a good brain condition works miracles: a good base of sufficient nutrients like carbohydrates, minerals, fat, vitamines and proteins is very important.

The so-called ‘photographic memory’

This also explains the patients who actually have a so-called photographic memory. There are some idiot savants (by the way a terrible misnomer and not so friendly) who are often autistic and have a fabulous storage system. One such person is Stephen Wiltshire (nicknamed ‘the human camera’) who has its own art store in London. He clearly has an extremely (over)developed visual memory with which he can draw the skyline of New York or any larger city just by flying around once in a helicopter. The details in his drawings are amazing! Below you can find a link to a YouTube movie about Stephen; it is really pretty amazing.

Link to Stephen Wiltshire YouTube movie 

However, if you think our memory is a camera then think again. Stephen’s storage systems may be like a real camera but in closer detail it isn’t: however brilliant his paintings are, he as well makes detailed mistakes. But the scale of his remembering still so many details baffles every scientist and no one really knows how the brain can do that.

People with the Savant syndrome can do amazingly much and it tells us something about what our brains can do. But it also tells us something more. With the Savant syndrome such a brain is not healthy or normal: often such patients can do some things extremely well but other normal things have not been developed much. Just look at a film like Rainman with Dustin Hoffman who plays the autistic Raymond Babbit. He can do a lot in this movie but taking care of himself in the normal world, he can not. Unable to drive, to do his finances, to shop, to care for children, all these normal things savants usually can not do. It is as if their extreme specialisation in certain areas of their brain has left other regions completely under developed. MRI studies do show that many savants have an extremely better developed right hind brain than healthy people. That can explain their extreme focus on visual details and their very weakly developed language abilities. Although their memory seems extremely developed, it usually is only concentrated on specific details. Real conscious learning strategies they do not use. Not only do they not need them, they actually can not use them as well. For that, you will need very well developed frontal lobes, the same ones that are responsible for their independence in real life.

Process nr 2: The active recall of information

Back to the normal memory processes. I already explained the normal storage process in which it is important to strategically influence this process to store as much information as possible. However, that is still not the whole picture. Although you can have stored very much information in your brain, in your Long Term Store (LTM), that still does not mean you can actually remember it all. You have to find it again. This remembering seems easy but scientists still haven’t figured out how it really works. Out of an enormous amount of information, just like a very large library, you have to find one specific book. This can only be accomplished by using memory cues. Often such cues are information units that are related to what you want to retrieve from your LTM. It is very important to fill your Working Memory (WM) with sufficient good cues. In this way such cues can trigger the correct information, they ‘fish’ in the large ocean for the right fish (information). This retrieval process requires some flexibility and creativity. Without good functioning executive functions you will be less efficient in the active retrieval of information, stored in your LTM. In the picture below I have tried to give an impression of this retrieval and recall process.

As you can see good cues are necessary to remember the correct information. The active remembering of information can be disturbed by more factors at the same time. First, the insufficient active generation of correct cues. It can be that the initiative or flexibility to generate good cues is severely limited. However, when this process works just fine, it is still possible that the association between the cue and the stored information has been too weak. For example, because the ‘memory glue’ was not strong enough. But this association can also be weak due to interference effects: other information can be related to a cue as well. As an example, GRASS LAND can be related too strongly to PIG or HAY STACK. Images of pigs or hay stacks pop up in working memory (WM) so that images of COWS and MILK do not pop up that quickly.

Another example of active recall is the recall of intentions or just made up plans to do. Every one knows the experience when walking towards the during a commercial on TV and not knowing what you were planning to do there. You can start walking back and start this journey again. Chances are you will then remember your original intention again. Another tip is to just look around in the kitchen. These tips work because your WM is filled with several cues. Your intention has been stored right at the moment that you started to move from the sofa towards the kitchen. Often this intention is related to something you saw on TV, or related to some part of the living room that you saw. Starting again at exactly the same spot where you came from, often triggers the right information in your WM. 

Working memory (WM) training: useful or not?

The last couple of years a new sort of function training has hit the news: the training of your WM. Especially the Danish professor Torkel Klingberg has become famous with this kind of training. In some studies he showed the positive effects of this training. But…is this the whole truth? For a long time most scientist did not think it was possible to alter the magnitude of your WM. It was 7 ± 2 units. Klingberg did not believe this and made a training programme that apparently can alter this WM capacity. In fact, it is an attention training because WM is almost synonymous with attention. It is the attention span which, according to Klingberg, can be enlarged by training.

At the beginning of this page I have already explained that the capacity of WM is constantly changing, due to our biodynamic brain system. That was already known for centuries. It is also known for quite some time now that intensive meditation (in fact, attention training as well), can change our brain in a positive way as well. Theoretically (and practically) it seems only logical that increasing WM capacity is possible after intensive training. However, Klingberg suggests that the effects on daily life are, at least, worthwhile. And just this claim has not been investigated thoroughly. For that we need larger studies, with much larger patient groups and well controlled study designs. The most beneficial effects have been found in small groups of children having ADHD (Attention Deficit Hyperactivity Disorder). It is not so surprising that this was found in children: most types of training do work better in children than in adults, probably due to their larger receptiveness and larger learning abilities. But more on this WM training on my pages about Attention training.

Summary: is it really that simple?

Yes it is. Storing information and remembering things really amounts to just paying more time and attention to it. And focusing on what you really want to remember. When it is essential to keep remembering it, just store it permanently on your computer or write it down.

You have to remember that cognitive strategies (conscious strategies) to store information will take much time and energy and you have to decide if that is really worth the effort. Especially when real memory problems are caused by brain damage or head injury, I do not recommend such complex and time-consuming strategies. I usually train patients to compensate: compensate with an electronic device such as a smartphone or PDA. I learn them how to store important facts and information logically and orderly on their computer.

Most training books have nice methods you can learn. But most methods do not result in a higher quality of life, especially not for people with serious memory impairments.

I have promised you to tell things that are not found in most books. Maybe they were not the kind of messages you hoped for. But, nevertheless, this is more real than you normally will see. It is based on my practice with a lot of brain-damaged people, and they have no intention to lie. They just suffer the consequences of brain injury and try to get a decent life. That's why I told you this, to get more out of your life as well when you have problems in remembering things. 

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