Memory, recall of learning and iteration

John Medina

Best guessing memory theory.

There are many theories about memory but we are now at a stage where we can begin to guess which ones are the most likely to have a high probability of being correct. 

First, it is most likely that memories do not exist in a single location in our brains but rather that each memory is a network of connections. When we recall something whole networks of neurons light up on fMRI read outs. 

Secondly it also seems likely that, although in the past, repetition was thought to improve memory, this was a misunderstanding of how and recalling or reviewing information actually work to improve memory. 

Memory is what makes learning useful. This does not mean that learning and memory are the same thing. Learning is how the things that we learn are connected to the things we have learned in the past. Memory, on the other hand, is our ability to recall those things that we have learned. 

A Misunderstanding. Although lot of memory research has seemed to show that memory is greatly improved by repetition, this site maintains that this is a misunderstanding. It is true that it can be shown on a cellular level that neuron connections are made stronger faster and more efficient by repeating their activation. This is because repeated activation increases the myelin wrapping around axons that connect the neurons. However, we know that in learning there is no such thing as true repetition. In fact ever time we learn something we are changing what we learned previously. This means that  our memory of experiences continues to change over time which can lead to distorted or false memories. It is the same for our memory of facts and theories except in those cases memories are more likely to improve. Sometimes we are merely adding to the other facts and theories that we know, but most often we are modifying one idea or understanding and thus are replacing it with a better more accurate idea. 

Memory question. So here is my question; if there is no true repetition in learning, need there be any true repetition in memory? There does not seem to be any good reason to believe that repetition as mentioned in the research on memory is any more un-extended or unaltered repetition than there is in learning. The research into memory indicates that both repetition and elaboration are essential to the ability to recall information. It should be pointed out, however, that it is possible that repetition alone without elaboration may not actually conducive to enabling recall at all. Although all the books talk about the importance of repetition, this seems to ignore the fact that true repetition is essentially impossible to generate.

Iteration leads to elaboration. Repetition may have a part to play in consolidation of memory, but it may not be quite in the way people have thought. Consider, the repetition involved in learning a skill is not repetition at all, but rather iteration. Each repeated action is actually a variation enabling us to adjust what we are doing and so improve our actions. Every time we recall, relearn, or reacquaint ourselves with something we have learned previously, we are adding new connections. Sometimes they are a complete revision but always there are some new connections. The mere fact that the recall or relearning takes place at a different place or time insures there are new connections. Repetition may aid in consolidating memory mostly because it provides the memory with further opportunity for elaboration. Elaboration may be what is critical rather than repetition as it is in fact iteration and not repetition at all. Be that as it may, even if repetition is in fact important in itself in improving memory function, this may still not be sufficient to recommend the use of drills in creating easily recallable memories.

In his book "Why Do I Need a Teacher When I've Got Google?" Ian Gilbert sums it up like this:

"Does rote learning work? Yes absolutely. Repetition reinforces connections between brain cells leading to better myelination and the creation of what can be lasting long-term memories. There are two significant downsides though. One, it is as boring as hell and demands high degrees of motivation of learners, self control and the sort of boredom threshold you would associate with train spotting or reality TV. Two, despite being effective it is not efficient. You may be achieving the results you want to achieve with your classes, so you are working effectively, but are you working efficiently? Could you, by using different memory strategies and techniques, achieve the same result by working less? Could you even achieve better results by working less?" 

It seems likely that memories were designed by evolution to have this kind of flexibility or malleability.

Although current neurological wisdom about memories is that they reside in specific places in the brain this site holds that there is sufficient evidence to consider an alternative idea. This site wishes to propose that memories are a web of connections. We know that when more connections are added to a memory, the memory becomes more elaborated and thus has more meaning. This site considers that this process incidentally creates more entry points for reaching the memories. The more connections there are to a memory, the more different directions your thinking could be taking and still arrive at the memory. The more connections there are the more pathways there are to the memory and thus the easier it is to find the memory and activate its recall.

Repetition in the sense of iteration seems to do two things. One, it causes myelin to wrap around the axons connecting the neurons which in turn allow the signal to move faster, more strongly and more easily. But in skill learning the main function is to obtain finer and finer control of the activity by the timing and strength of the signal. Two, it would seem to also activate the generation and growth of new synapses, dendrites and axons when they are activated. In his book "Brain Rules" John Medina gives us a description of how the hippocampus and the cerebral cortex are connected and work together in creating memories:

"The first army [of nerves] is the cortex, that wafer-thin layer of nerves that blankets a brain... The second is a bit of a tongue twister, the medial temporal lobe. It houses another familiar old soldier, the oft mentioned hippocampus. Crown jewel of the limbic system, the hippocampus helps shape the long-term character of many types of memory...

How the cortex and the medial temporal lobe are cabled together tells the story of long-term memory formation. Neurons spring from the cortex and snake their way over to the lobe, allowing the hippocampus to listen in on what the cortex is receiving. Wires also erupt from the lobe and wriggle their way back to the cortex returning the eavesdropping favor. The loop allows the hippocampus to issue orders to previously stimulated cortical regions  while simultaneously gleaning information from them. It also allows us to form memories...

A conjecture about memory. As you may know, science as yet has not discovered how memories are formed. However, this site has extrapolated a conjecture as to how memories may possibly be brought into being. It should be noted that this idea has not been tested in any way, and so cannot even be designated a theory. It is plain and simple speculation. But it does seem to fit a lot of what is known so far about memory formation. As such it may have as much or more validity than the similar speculation that memories reside in a fixed single location.

Memories are networks or webs of neurons.

When we experience something or learn something, an electric impulse runs through all those parts of the brain that are involved in the experience or the learning. This happens simultaneously and sequentially as we experience or learn it. Because these areas were activated together the connections between them are strengthened and become a web or network of connections that can easily activate together again. Thus a memory is formed, not in some single area of the brain, but as a network of connections spread across many areas of the brain. Every time the memory is recalled the connections would be further strengthened. However, if we do not recall the memory, it would degrade and the connections would wither. Indeed the synapses that connect them would break off and shrivel.

Connection webs. This conjecture is based on the idea that memories may simply be these complex webs of connections between neurons. This would necessitate that meaning is just how the bits of brain are connected together and how they tend to fire in unison as a circuit. This would account for the fact, that when we add more connections through elaboration, the memory becomes both more meaningful and more easily recalled. These webs of connections have end points and connections. Every endpoint for a memory can also be thought of as an entry point to that memory. This means, contra to common sense, the more connections there are the easier the memory is to recall. This plurality of entry points plus the strength of each link would therefor be what enables a memory to be recalled. More connections would mean more meaning and incidentally more entry points which would mean it could be activated by entering the circuit in more ways thus improving recall. When we find a memory hard to recall it is usually because this seeming random structure does not present us with the recall opportunity that we require. We simply can’t find a path to it.

Indeed life loggers such as Gordon Bell who try to record their whole lives have many of the same problems remembering as the rest of us. Even though they may have a photograph or video of every moment of their lives they have nearly as much trouble as we do in finding the memory they are looking for. How does a person who has filmed his whole life find that bit the memory he is looking for? It can be easy if he knows the time and date and his photo or film has readouts for time and date. It might be easy if he knows where he was when the memory was filmed. Again this would require that his film or photo has readouts for GPS. Otherwise he must use the memory in his brain to track down his memory on film.

In some ways our brains also use contextual markers such as date time and place to help find memories. Time of day can be a good contextual marker to help us find a memory but places work even better and are the basis of mind palaces. You are much more likely to remember something if you return to the place where you first learned it or experienced it.

To continue with our conjecture we can ask how brain structures might function to develop such webs of connections. Perhaps the most important rule for brains is that 'neurons that fire together wire together'. Neuroscience research has produced a great deal of support for this idea, so our conjecture starts with it. So the question is, "How does this happen?" The simplest solution would be that when neurons in the cortex fire at the same time they tend to sprout new synapses which connect to other neurons or that have axons the are growing in the direction of the other neurons that are firing at the same moment and that this extending growth would continue until the two or more neurons that fired at the same moment eventually connect up. The problem with this solution is that to grow new synapses and maybe dendrites and even axons so that they reach far distant areas of the brain would take a long time to accomplish perhaps years. This does not seem to be a likely solution.

However, new synapses do seem to be involved. In her book "The Creative Brain" Nancy C. Andreasen says:

"In this particular case, when the neuron is stimulated to a sufficient degree to create a memory that needs to be preserved, a variety of chemical messages are sent to the cell nucleus, where in turn genes are expressed and send messages back out to the synapse that say: 'build more synapses and create new synaptic connections so that you can keep this information for a long time."

The process then, would have to be more complex. What we do know is that the formation of memories has something to do with neurogenesis and the creation of new neurons especially in the brain structure called the hippocampus. There are many theories about how memories are stored in the brain. In his book "Connectome" Sebastian Seung suggests that memories may be stored in the part of the brain called the hippocampus. He says:

"The hippocampus belongs to the medial temporal lobe... Some researchers believe that the hippocampus serves as the "gateway" to memory; they theorize that it stores information first and later transfers it to other regions like the neocortex."

This site holds that memories are not likely to be stored in a particular area of the brain as suggested above, but rather reside in the connections themselves and how different areas of the brain are connected up. If this is the case, the hippocampus may simply act as a device to facilitate the connecting of one part of the brain to another. The reason this seems likely is that there is a complex of white fibers that connect the hippocampus to every part of the cortex known to encode declarative memories. There are connections seemingly running from every part of the cortex to the hippocampus and back again. 

Let us suppose that the formation of each new memory depends on the existence and development of a single new neuron. We can further suppose that each new neuron coming into existence in the hippocampus simply floats around until a number of signals come down from the cortex indicating that something is happening. Suppose then, that the new neuron is attracted to these signals and connects
via its synapses to all these signals and sends the signal back to all the same ares of the cortex connecting them all up. The new neuron would, in that case, not contain a memory, but rather act as a device to connect the various parts of the cortex that have become currently active. Because these connections are already in place the new neurons could connect up to all the active cortical areas almost instantly. How might this come about? When cortical neurons become active they would send those signals to the hippocampus via their many connectors. The new neuron would be attracted to the charged axons and dendrites and would quickly connect to those active fibers thus connecting up all the incoming signals. It would then find the fibers going back to the same cortical areas (which would be near bye) and send them back as a whole to all the same cortical neurons involved thus connecting the whole circuit. In this way a memory would be formed and the firing neurons would wire together.

Synapses are the connectors in the brain. In her book "The Creative Brain" Nancy C. Andreasen says:

"Each of these neurons is designed to make multiple connections to other neurons. The nerve cells multiply their connective capabilities by sending out dendrites, which in turn expand by adding spines. Along the spines are multiple synapses. At the axonal end of the neuron there are also axon terminals containing synapses. The synapses are the real 'action sites' within the brain. There are different types of neurons, as defined by their number of axons and the complexity of their dendrites, and we do not have an accurate way to estimate the total number of synapses in the entire human brain. A typical estimate is that each nerve cell possesses approximately 1,000 to 10,000 synapses.

...As our brains form during fetal life, nerve cells grow and establish connections to one another. Some of them are hard wired and genetically determined, but many are shaped by our experiences. Each neuron does its work by talking across synapses to multiple other neurons at more or less the same time, and each of those neurons are talking to many others. (The technical term for for these interacting neurons is neural circuits.)

...The neural circuits of the brain are designed to monitor and modulate one another. Sometimes the connections send excitatory signals, and sometimes they send negative, or inhibitory, signals. Some connections create short feedback loops between neurons and some have long loops that spread across longer spans of the brain. It is estimated that a large feedback loop covering the entire brain takes only five or six synapses."

Whether one or more of the synapses fire and allow the signal to proceed, depends on the strength of the incoming signal, which in turn depends on the amount of myelin wrapped around its axon. The more times a signal travels along an axon, the more myelin wraps around it, the better and stronger and faster the signal will travel along it in the future. The wrapping of the myelin not only increases the strength speed and efficiency of the signal but also determines the path the signal will take.

We know that new neurons are formed in the hippocampus by means of neurogenesis. But what is the purpose of these new neurons if it is not to store new memories? This site holds that the purpose of these new neurons is to connect fibers that run from the hippocampus to every part of the cortex. In other words although connections in a fully formed brain run from the hippocampus to every neuron in the cortex they only connect when a new neuron formed in the hippocampus makes that connection. When such connections are made in this way we hold that a memory is formed. In the beginning each memory may be connected through a single neuron in the hippocampus. But this is not the most efficient way for neurons in the cortex to be connected. Instead its more like how parcels are dealt with by 'Federal Express'. All parcels first sent to a central hub before being resorted and sent to their destinations. Neurons in the cerebral cortex could be connected more directly to one another. They could be directly connected in the neocortex the layer just under the cortex. Alas, as was pointed out earlier, it would simply take too long for a memory to be formed by forming new synapses and growing axons. However, we can suppose that even while the memory is being maintained by the neurons in the hippocampus that synapses still bud, dendrites still proliferate, and axons still extend all in an effort to connect up with other neurons that are firing at the same moment. Although there are no special fibers to connect the neurons in different parts of the cortex, here is what might happen. Gradually over perhaps years these cortical neurons would become more directly connected up. So it would take a long time, but so what, the memory is intact as long as the neuron in the hippocampus remains undamaged and is fired off at regular intervals that correspond with times previous to when they are about to be forgotten.

As these new pathways become strong and shorter in length, they would be used in preference to the long connections going through the neuron in the hippocampus and the need for that neuron in the hippocampus would diminish, and it would eventually die off leaving the memory in cortex fully connected up, without the hippocampus playing a part any longer. All this requires that the memory be activated often over a long period of time, possibly many years. This process would ensure that the number of neurons in the hippocampus never get to be too many, for as new ones would be forming old ones would be dying off. This leaves us with a situation quite different to how memory is usually thought of, where in the cortex a memory would not just be in one place. Such a memory could perhaps be activated at any or all of the connected junctures that make it up. This could be thousands of places in the cortex. Not only that but these same junctures could also be part of other memories.

The webs or matrices of memory. If our memories are, as suggested, complex webs of connections of neurons scattered across the cortex, then iteration of that memory would accomplish two things simultaneously. It would strengthen the connecting axons by the wrapping of extra myelin around them to protect and optimize them. But at the same time it would add more connections (even if those connections were only those that connected the memory to the time and place at which the recall took place. Details would be difficult to recall because they would be at the periphery of the memory and not always activated each time the memory as whole was activated. On the other hand the central core of the memory which John Medina calls the gist of the memory would be easy to recall because that is what would always be activated each time the the memory was recalled. To find a memory a person would have to navigate through a maze of connections, but the central core of a memory, the gist of the memory, would be found because it would be surrounded by so many entry paths while the details would have few entry paths.

It would then follow, that a thousand iterations of activating a memory would have little effect if they all occurred in rapid succession, because their importance would involve two essential functions. One function would be the putting off the natural process of neurons and their connections (synapses) atrophying when they are not being activated. The other function would be the making sure that any two neurons involved in the memory, and thus fired when the memory is active, would continue to extend neural connections toward one another. A strongly connected memory through iteration and elaboration in the early stages of memory consolidation would be of help, but more spaced iteration and elaboration over time would make sure the process continued. What the brain would need is convincing that the memory is needed, and thus cause it to stop or postpone the otherwise entropic process that starts the moment the memory is minted. Iteration at regular intervals over a long period of time could interrupt the dieing off of connections at the very moment when it is most needed, when it is just about to happen and the memory is just about to disappear forever.

Neural Darwinism. One of the problems with the above conjecture, about how memories are formed, is that we are still not sure that axons and dendrites continue to grow much after the first sixteen or so years of life. However, even if this growth does not occur much in adults this does not necessarily invalidate this conjecture. There is another theory mentioned in Sebastian Seung's book  "Connectome" where he suggests that synapses may not be created on demand but rather created randomly. He says:

"Perhaps synapse creation is a random process. Recall that neurons are connected to only a subset of the neurons that they contact. Perhaps every now and then a neuron randomly chooses a new partner from its neighbors and creates a synapse. ...Synapse creation alone, however, would eventually lead to a network that is wasteful. In order to economize , our brains would need to eliminate the new synapses that aren't used for learning. ...You could think of this as a kind of survival of the 'fittest' for synapses. Those involved in memory are the 'fittest' and get stronger. Those not involved get weaker, and are finally eliminated."

This could mean that although synapses may not be created in response to the need for a new memory many new synapses may be created randomly in response to increases in the formation of memories.  

If we take out the possibility of growth of neuron pathways and plug in "Neural Darwinism" the conjecture about declarative memory formation is still viable. In this case we would have to consider that there may be many possible pathways between any two neurons in the cortex and although the initial one created by a new neuron in the hippocampus would be strongest at first this would eventually be replaced by a more direct path through the neocortex. Let us suppose that initially when a memory is first laid down two different pathways are created, one that goes to the hippocampus as has been explained already, and one that goes through the neocortex in a long laborious twisting and back tracking journey through the tangle of neuronic connections. Sometimes, with luck, this path may be shorter than the one through the hippocampus, but usually it would be much much longer. Let us further suppose that every time we recall the memory that connects these two neurons in the cortex that both these pathways are activated. Not only that, but because of the random appearance of new synapses connecting new neurons, maybe another pathway may open up that is shorter or maybe several shorter pathways open up and maybe all of these now activate and form a circuit. The next time the memory is recalled the shorter pathway may be activated while the longer one may be inhibited and not activate. After considerable time and recall and the finding of shorter and shorter pathways and the deactivation of the longer pathways, the path through the neocortex could become quite short indeed. This could be so much so, that the path that includes the hippocampus may not be needed, and may itself be inhibited and deactivated. The process would not stop there but continue throughout life. Each time a memory was recalled or relearned it would try to find a shorter faster path.

A final note about this conjecture. The problem with this conjecture is that it still does not explain how the brain finds a memory in order to activate it. And how would the brain know when it has found it?  Answers even speculative ones simply beget more questions.

The changeability of memory.

Memory as change. Change, as is expressed often on this site, means learning. Changing memory is something that does not make a lot of sense in terms of how we understand computers. In a computer if something is saved it is stored in a particular area of the computer (the hard drive) in a perfect form to be recalled. This is not how the brain works. There is no decision to save in the brain. Short-term memory becomes long-term memory if it is activated often, that is if it is relearned or revisited, accessed, or recalled. Saving, if we could still call it that, takes place over a long period of time. But, as suggested above, learning and thus memory is not mostly about repetition but rather iteration where what is learned is constantly being altered and extended and thus changing. Recall, it is being suggested here, may work in the same way, with the replacing of lost associations and adding new associations every time a memory is recalled.

What associations? It seems most likely that some associations, originally part of a memory, are actually lost forever and that our brains have make guesses about these lost elements. In this way memories get altered as these guesses can be both distorting or completely wrong. Also every time we recall a memory we are also making a new memory. Every time we recall something there are thousands of new associations just waiting to be attached. First there are the associations with what ever the reason was that you made the effort to recall, or the intrusive external event that triggered the memory to automatically pop into consciousness. These can be particularly strong associations. Then there are the associations that comprise the external environment at the time when we are in the process of recalling, and probably the thoughts we have had during and just after the recall. These are weaker often unconscious associations, but they are there nevertheless.                          

Changeable memories. Memories tend to change over time. They seem to be unstable. This is consistent with our theory above, as elaboration would be essential to consolidating any concept, action or memory. Sometimes memories change for the better, and sometimes they change for the worse, but they change. How memories change has partly to do with how they are stored and accessed. It is said this is a function of a memory's storage strength and retrieval strength. Storage strength enables the planning and mapping of reality in memory. Retrieval strength enables the continual updating and accessing of what is relevant in memory. 

Storage strength. Storage strength increases with familiarity, the number of times the memory is accessed. Accessed can mean recalled, but it can also mean studied, tested or any kind of revisiting of the memory. Storage strength is about memory starting off being impermanent. A memory starts off in short term memory. It has an initial storage strength based on the amount of associations it makes with other memories residing in our brains and the intensity of those associations. Storage strength does not weaken but is rather in constant danger of disappearing. If not revisited it will completely disappear. If there are no intense associations attached to it it will disappear quickly. If there are intense associations attached to it, it will last longer but it will still disappear. However, if a memory is revisited it will last quite a bit longer from the time of that revisitation. In fact, each time a memory is revisited the amount of storage strength increases allowing the memory to survive a longer and longer time after each revisitation. 

If we think about this it becomes obvious that we can get the most out of storage strength by not revisiting a memory until it is about to disappear. That way we get the most time available for recollection for the least amount of revisitations. So as we revisit each memory they last longer and longer in short term memory until they reach a condition of lasting so long they become a permanent memory and are said to then be in long term memory. It might seem that storage strength is a function of repetition in that the number of times a memory is recalled increases storage strength. However, whether a memory is recalled or not from a statistical point of view depends on the number of pathways leading to it. It is far to simple to see storage strength as function of repetition. It depends on elaboration as much as specific repetition. Then too, the number of times a memory is recalled is not as important as when those recalls take place. Ultimately memories are allowed to disappear unless they prove to be useful and storage strength is a judgment of how useful each memory is.  

Retrieval strength. Retrieval strength on the other hand is about how quickly a memory comes to mind. The number of pathways to a memory, the intensity of those pathways, and how recently it has been revisited are the main provisions that govern the strength of retrieval strength. While retrieval strength is also improved by the number of revisitations of the memory it is clearly more greatly increased by the sheer number of associations connecting to that memory and the intensity of those associations and when the memory was last recalled. When we revisit a memory retrieval strength is high and it gradually weakens as time goes bye. If it is revisited again the amount of associations to it goes up and its retrieval strength goes up because of that, but then it weakens again until the next time it is revisited. Each time a memory is revisited its retrieval strength comes back stronger than the last time it was revisited but then it weakens till the next time it is revisited. 

However, each time a memory is revisited it starts to weaken, but it weakens more slowly with each successive revisitation. This process goes on forever. It is still working even after the memory has gone into long term memory. This seems to be true of even the longest existing, most stable, long-term memories. If a memory has been in long term memory for a long term without being revisited it seems it falls back into short term memory if it is revisited. In his book "Brain Rules" John Medina puts it like this: "There is increasing evidence that when previously consolidated memories are recalled from long-term storage into consciousness, they revert to their previously labile, unstable natures. Acting as if newly minted into working memory, these memories may need to become reprocessed if they are remain in a durable form. ...If consolidation is not a sequential one time event but one that occurs repeatedly every time a memory trace is reactivated, it means permanent storage exists in our brains only for those memories we choose not to recall! Oh, good grief."   

Types of memories.

Types of memories. Neuroscientists tend to talk about many different types of memory. There are three major types of memory. First memory is usually divided into explicit or declarative and implicit or non-declarative memory. Explicit memory is further broken into episodic and semantic memory. Explicit or declarative memory is also be divided into other types of memory. They are long-term memory, short-term memory and working memory. Implicit memory or non declarative memory is also called procedural memory.

Here we will be mostly talking about semantic memory, working memory and some episodic memory. Memory athletes use their abilities to remember information (semantic memory) so the methods they use work mostly with that type of memory.

Explicit or declarative memory.

Long-term memory. 

Long-term memory. Long-term memory is usually considered to be concerned with both, semantic memory and episodic memory or all explicit/declarative memory. Long term memories are those memories that are considered to be permanently stored and do not require further recall to keep them accessible.

Semantic memory.

Semantic memory. Semantic memory is the type of memory that deals with meaning and structures made up of meanings. That is it the memory of concepts and statements that are constructed from concepts. Semantic memory can also understood to be our memory of facts about the world or how we understand how things are. Thus it is also our theories about the world and how things work in it. It allows us to predict what will happen given certain starting conditions. It allows us to understand and predict outcomes in limited sets of circumstances. 

Semantic associations. Semantic memories are structures of hundreds semantic associations that go to make up each concept in a thought, and the stringing together of these concepts into further meaningful structures that could be declared as statements. This is the type of memory discussed in this site's section on meaningfulness. The associations in this type of memory are what provide the meaning of a word, a concept, a sentence, a text. These associations by linking together produce an abbreviated or symbolic form of the memory. Words for instance are symbols that stand for concepts. Words then are associated with all the elements that make up their meaning but when we recall a concept from memory we will in all likelihood recall only the word into consciousness. In a similar way when we recall some text we will recall only the gist (the meaning) and not word for word text. The brain abbreviates information so it can be processed efficiently. Meaning is a web of associations that we hold in memory although we only access this central core of what it is.

John Medina points out that a word on a list is best remembered if we we make an effort to associate it with as much meaning as possible. The concept or word apple is much less elaborately encoded than say his Aunt Mabel's apple pie. The concept or word apple however, has very elaborate encoding including all the associations needed to give meaning to that word or concept. If when we try to remember the word we concentrate on the number of diagonal lines in the word we are ignoring all the elaboration at our disposal. If instead we think about Aunt Mabel's apple pie the meaning is very elaborate.  Aunt Mabel's apple pie deals with not one but three strong concepts, pies, apples and Aunt Mabel. On top of this there is the fantastic smell of the pie, the delicious taste of the pie, its texture, its usual visual appearance, how it made us feel, etc. Aunt Mabel's pie can be very intrusive. Sudden exposure to pies, apples, aunt Mabel, pie smells, pie tastes may all invoke Aunt Mabel's apple pie into our stream of consciousness.

More about memory webs. It is in this type of semantic memory that it is easiest to see how memories could be webs of connections. The way to get a glimpse of how webs of connections might coalesce into memories is to start with the basic units of semantic memory, the concepts themselves, and more specifically concepts of objects. An object concept is a concrete form existing in the world. We know what these object concepts are because we know their meaning. These object concepts come in many sorts. One sort of object concept is a specific object. Such objects are Betsy the cow, Fido the dog, Bradley the man, Australia the country, and Mabel the yacht. Such object concepts are not a class or a category, or if they are, they are a category with only one member. Also they do not have to have specific names. They can be something like my blue pen or your red scarf. Most object concepts however are a class or a category and thus have many members. The most useful of these object concepts are the next level of abstraction. Such object concepts are a category which has specific objects as its members.

A ball. Let us consider the object concept "ball". We all know what a ball is, but how do we know it? It is suggested here that we know what a ball is because of its connections to memories of specific balls. The concept ball has probably thousands, no millions, no billions of connections. Every time you saw a ball, felt a ball, played ball, bounced a ball, heard about a ball, thought about a ball, the connections would be made and activated but not brought into consciousness. This site holds that it is these connections when activated that give the concept "ball" its meaning, that they are in fact that meaning.

A sphere. Consider the concept of a sphere. A sphere is an aspect of a ball. While most balls are fairly spherical, some footballs are more egg shaped. Although a sphere is not really an object at all we often use the words that stand for aspect concepts interchangeably with those that stand for object concepts. You might describe a sphere as being ball shaped. But this is not really correct. In fact the opposite is true most balls can properly be described as being spherical. When the concept ball is activated the concept sphere is also activated as part of its meaning. Following from our theory a sphere unlike a ball would not have such a large number of connections. It would have only a few connections. However it is still a strong concept because it has a very strong connection to the concept ball and when the concept sphere is activated the concept ball, would for the most part, be activated also as part of its meaning, even though the reverse is more correct. In this way every concept would be a fantastic web of connections. Remember in just six connections you can probably connect to any neuron in the entire brain.

Concept formation. So how might these concepts be built up as we learn and grow? What we know about building memories is that the "connecting axons" of neurons that are activated with a memory get more myelin wrapped around them, making them stronger and quicker. On the other hand the "connecting axons" that are inhibited from becoming active, or are simply not activated, tend to wither and die. 

Let us suppose then, that when forming connections for concepts children select members that seem, for whatever reason, similar to them. Let us call these theories about what concepts are, or concepts that do not match concepts as they are understood by a particular culture of adults. They would be sort of potential concepts or incorrect concepts. These incorrect concepts would be useful for building an internal model of reality, but fairly useless for communicating with others.

Modification. Thus infants would have to modify these connections as they gained information about what others in their culture accepted as being connected, or as being members of that concept category. For this to happen some connections would continue to be activated while others would be inhibited from being activated. The axons that continued to be activated would continue to be part of the meaning of the concept and the axons that were inhibited from being activated, would die off and no longer be a part of the meaning of the concept. On the other hand a child might miss some members of a concept category and have to modify the concept by adding members. This would simply be a matter of firing the various connections and at the same time adding the new connections. They would be more weakly connected at first but would get stronger, the more they were activated as part of the whole concept activation.

Semantic memories. Semantic memories then are concepts, or complex interrelations of concepts (stories), and they are meant to be changed each time they are remembered. While they may seem like static unchanging things they are in fact constantly in the process of changing. Every experience of an object, every recall of it, provides us with more information about it and even when we think we have an immutable understanding of what it is we are still deleting some connections that are not quite right, we are adjusting other connections, and still adding new connections. Not only does our understanding of concepts constantly change but also often the objects themselves change. A concept like a ball may not change but living concepts like animals, insects and humans get older, lose body parts and change in appearance. Concepts of place also change. Trees grow, die, change their leaves. Man made structures like buildings also change as they are built and knocked down.  For this reason semantic memories are meant to be infinitely flexible constantly expanding and contracting to fit the current state of things. 

Episodic memory. 

Episodic memory. Episodic memory is the type of memory that deals with an event or episode in ones own life where a whole lot of information was attended to, and was thus processed into associations that are all welded together in to a whole unit of memory. It is a whole experience that we have experienced, and it has been thought that we should be able to replay it, almost as if it was happening again, when we recall it. It’s like a snapshot or a recording or a video. 

Episodic associations. Episodic memories are structures of hundreds of episodic associations that go to make up these episodes or events. In his book "Brain Rules" John Medina tells a story about an episodic memory of playing fetch with a huge Labrador, that surprised him by coming out of a lake and shaking water all over him. He continues:

"What was occurring in my brain in those moments? As you know the cortex quickly is consulted when a piece of external information invades our brains - in this case, a slobbery, soaking wet Labrador. The instant those photons hit the back of my eyes, my brain converts them into patterns of electrical activity and routes the signals to the back of my head (the visual cortex in the occipital lobe). Now my brain can see the dog. In the initial moments of this learning I have transformed the energy of light into an electrical language my brain fully understands. Beholding this action required the coordination of thousands of cortical regions dedicated to visual processing.

The same is also true of other energy sources. My ears pick up the sound waves of the dog's loud bark, and I convert them into the same brain-friendly electrical language to which the photons patterns were converted. These electrical signals will also be routed to the cortex, but to the auditory cortex instead of the visual cortex. ...This conversion and this individual routing is true of all energy sources coming into my brain, from the feel of the sun on my skin to the instant I unexpectedly and unhappily got soaked by the dog shaking off lake water. Encoding involves all of our senses, and their processing centers are scattered throughout the brain.

...In one 10-second encounter with an overly friendly dog, my brain recruited hundreds of different brain regions and coordinated the electrical activity of millions of neurons. My brain was recording a single episode, and doing so over vast neural distances, all in about the time it takes to blink your eye."

Episodic associations are often only peripherally encoded in a memory. In this case one focuses attention on a specific item of interest, and much of the other information is ignored and unprocessed. However, although this peripheral information is not part of what is recalled in the memory trace, it does still  provide some pathways for activating the memory. This it turns out is very important for enabling recall of any sort. It has been found that the most significant way we can help people remember something, is to put them in an environment as close as possible to the one where they first encoded the information.

Memory episodes.The episodes of episodic memory are usually understood to be constructed or built up in exactly the same way as semantic memories and are thus constantly changing. This makes memory episodes unreliable. While each episode only occurs once it must be recalled many times in order to become eligible to go into long term storage. However every recall is an opportunity to contaminate the memory. It is a catch 22. the more it is recalled the easier it is to remember it but the more it is recalled the more it becomes contaminated. Every recall adds more associations and if those associations are often the same ones they can become strongly associated and thus distort or change the original episode. The only way to avoid contamination is to make each recall is supplemented with new information that more accurately describes the episodic memory. For instance recalling the memory could prompt the investigation of an account of the episode by somebody else which could more accurately modify your own account which could be biased by your memories and beliefs acting as a perceptual filter.

Short-term memory. 

Short-term memory. The relationship between short-term memory and working memory is interpreted in various ways by different theories, but it is usually understood that the two concepts are distinct. Short-term memory generally refers to the short-term storage of information only, and it does not entail the manipulation or organization of information held in the memory. Thus while there are short-term memory elements in working memory models, the concept of short-term memory is usually conceived as being distinct from information manipulating components.

Short-term memory is labile, unstable and of limited duration. It is tending to spontaneously decay from the moment it comes into existence. In order to overcome this limitation of short-term memory, and retain information for longer, information has to be periodically recalled, iterated, or rehearsed. This is called covert rehearsal. It can be performed either by articulating it out loud, or by mentally simulating such articulation. In this way, information can re-enter the short-term store and be retained for a further period.

Working memory.

Working memory. Working memory is a theoretical framework that refers to structures and processes used in the very brief awareness of thinking and manipulating of information. Working memory could also be understood as being working attention. Working memory is a busy temporary workspace, rather like a desktop, that the brain uses to process newly acquired information. Working memory is the processor part of consciousness. The man whose legacy best characterizes this process is Alan Braddeley who described working memory as a three component model; auditory, visual and executive.

1. Auditory working memory. The auditory part of working memory is the part that deals with sound. It is the part that retains linguistic information and processes it.
2. Visual working memory. The visual part of working memory is the part that allows some visual information to be retained in memory and processed. Braddeley saw it acting as a sort of imaging-spatial sketch pad.
3. Executive working memory. The executive part of working memory is the part that keeps track of individual threads of thought and which keeps them separate and keeps each together as a chunk of information. Thus professional chess players can play several opponents at once and keep each game separate in their minds.

Working memory as thinking. Working memory is essentially what you are thinking about at any given moment, what you can manipulate in your mind, and what you can hold in your mind without resorting to recalling another memory. In 1956 George Miller wrote his classic paper about the number 7 plus or minus 2 which seemed to be a sort of limit on the number of items that people could hold or manipulate in this working memory. Now one might be tempted to think that this would preclude humans from remembering numbers greater that seven to nine digits. This is of course not the case.

Chunking. As we know, people remember phone numbers and some people can remember great long strings of numbers like pi, which can be a great number of digits depending on the amount of accuracy you might want. How do people remember these long collections of digits? It is called chunking. We simply cut the number up into smaller numbers (chunks of the original) that can be recalled one after the other. You might break up a mobile phone number up into two lots of five digits but more likely you will break it up according to the rhythm you use when you speak. The number of chunks may be three or four. There are many ways to connect these units together. One way to connect such units is to use a memory system. However, with a small number of units it is not so important to use a memory system you can simple find your own way of connecting the units in the correct sequence. So chunking is a process with which the amount of information a human can hold in working memory can be expanded. Chunking is performed by organizing material into meaningful groups that make up each chunk.  

Chunking in working memory. Chunking is invaluable in enabling working memory to perform efficiently. Although working memory can only hold about seven units or concepts at a time, by means of chunking working memory can be enabled to deal with and manipulate large amounts of units concepts and information. With the use of chunking large amounts of information can be carefully placed in long term or short term memory in such a way that it can be recalled bit by bit in the correct sequence. Although the average person may only retain about seven different units or so in working memory, chunking can greatly increase a person's recall capacity. When used well chunking can make memory seem almost magical.

Chunking in chess. In his book “The Art of Learning” Josh Waitzkin explains how learning to play chess is memorizing various skills that can readily be seen as chunks that are clearly embedded one inside the other. He says that, first you learn how each piece moves on the board, and then you learn how each piece moves against each other piece on the board. Then you learn how pieces can move and attack together in various combinations. Then you learn the great games of the various chess masters. Eventually you begin to see each game chess board as a pattern of potentials with only one or only a few good outcomes. Chess masters have memorized so many of these great games that they only have to glance at a board to know the best move to make instantly.

This chunking allows anybody to remember almost unlimited amounts of information in a given order. Items sit in a chunk which in turn can slip within another chunk which can nestle inside yet another chunk. Theoretically this could go on ad infinitum. Most memory systems rely on chunking. Practice and the usage of existing information in long-term memory can lead to additional improvements in one's ability to use chunking. In one of Anders Ericsson's testing sessions, an American cross-country runner was able to recall a string of 79 digits after hearing them only once by chunking them into different running times. Although he knew little about memory systems he created this system seemingly by simply trying to remember large numbers of digits.

Implicit or non declarative memory.

Implicit memory. 

Implicit memory. Implicit memory is the memory of how we do things. It is called non declarative because we do not declare it. Indeed when it is working well we do not even have to think of how to do it. The memory is in the repetition of the action. This is sometimes called motor memory or procedural memory. It is a type of memory in which previous experiences aid in the performance of a task without conscious awareness of these previous experiences. Evidence for implicit memory arises in priming, where subjects show improved performance on tasks for which they have been subconsciously prepared. Implicit memory also leads to the illusion-of-truth effect, which suggests that subjects are more likely to rate as true statements those that they have already heard, regardless of whether they are true or not.

Research into implicit memory indicates that implicit memory operates through a different mental process from explicit memory. Instead of connecting to the hippocampus implicit memories connect to the cerebellum and the dorsolateral striatum.

The cerebellum ("little brain")is a structure located at the rear of the brain, near the spinal cord. It looks like a miniature version of the cerebral cortex, in that it has a similar wavy, or convoluted surface. The cerebellum is located behind the top part of the brain stem (where the spinal cord meets the brain) and is made of two hemispheres (halves). The cerebellum receives information from the sensory systems, the spinal cord, and other parts of the brain and then regulates motor movements. The cerebellum coordinates voluntary movements such as posture, balance, coordination, and speech, resulting in smooth and balanced muscular activity. It is also important for learning motor behaviors. The cerebellum is highly involved in implicit memory.

The dorsolateral striatum is also essential in the creation of procedural memory or motor learning and thus is associated with the acquisition of habits. It is the main neuronal cell nucleus linked to procedural memory. It is part of the the basal ganglia circuit. Overall the basal ganglia receive a large amount of input from cerebral cortex, and after processing, send it back to cerebral cortex via thalamus. The cortex sends excitatory input to the striatum. The striatum  sends its inhibitory output on to the globus pallidus. The globus pallidus can also be excited by cortical activity, namely by a pathway that travels through the subthalamic nucleus first. The globus pallidus is really divided into two segments, only one of which sends output (yet again inhibitory!) to the thalamus and on to cortex, thus completing the loop.

Essentially, two parallel information processing pathways diverge from the striatum, both acting in opposition to each other in the control of movement, they allow for association with other needed functional structures. One pathway is direct while the other is indirect and all pathways work together to allow for a functional neural feedback loop. Many looping circuits connect back at the striatum from other areas of the brain; including those from the emotion-center linked limbic cortex, the reward-center linked and other important motor regions related to movement. The main looping circuit involved in the motor skill part of procedural memory is usually called the cortex basal ganglia thalamus cortex loop.   

Either the cerebellum, the dorsolateral striatum or the whole basal ganglia may possibly play a similar role in implicit memory as the hippocampus does in explicit memory. 

These memories are often called non declarative memories because although we do not recall them into consciousness as we perform them we could not declare them if we did. They are activated as an activity or a skill and accomplished without us having to consciously think about doing it. It is automatically activated when we wish to use it.   

Procedural memory. In daily life, people rely on implicit memory every day in the form of procedural memory. This type of memory allows people to remember how to drive their car or ride a bicycle without consciously thinking about these activities. It allows us to build up skills requiring co-ordination and fine motor control such as playing a musical instrument, or playing a sport or reacting to defend yourself.

Once we have learned some skill to a sufficient level there is a process which helps to make those actions or reactions automatic, thereby allowing them to sink to a merely physiological level, and to be performed without attention. When riding a bike we may however, modify our performance consciously going this way or that on the bike, or go faster or slower. But the schema of bike riding is unconscious. Of course when you are learning a skill you have to think about it often, and break it down into manageable units or schemas that can then be manipulated more easily. This is another type of chunking. As you continue to learn these schemas gradually sink out of consciousness into automatic activity. There is much about this in the book "The Art of Learning" by Josh Waitzkin. This is covered more extensively on this site in the section on thin slicing, which deals with the creativity of the unconscious. 

Memory as link strength and elaboration.

Memory duration. Memories can last minutes, days, months, years or a lifetime. How long memories last depends on how often they are used and how elaborately they are connected or linked to other memories. Memory experts tend to think of these as two different process, but this may not necessarily be the case. We know, for instance, that if connections are not used they disconnect and the synapses involved tend to die off. Memories with lots of connections would also be more likely to be accessed in a search. So it could be said that the amount of elaboration increases the possibility of use. Conversely the amount of use increases the amount of elaboration, because use means recall. So any case it is clear that these two processes are inextricably bound together. The amount of elaboration increases the possibility of use, and use determines whether the associations become increasingly elaborate or whether they become less elaborate.

Elaborate encoding. The researchers have called the elaboration of associations 'elaborate encoding'. Elaborate encoding is all about meaning. That is to say, the more associations or connections to other information the more meaning, and thus the more easily memorized. Elaborate encoding is accomplished in two quite different ways: 

Initial elaborate encoding. Elaborate encoding can be accomplished at the time of initial experience or learning (encoding). Most of this elaborate encoding takes place in the first few moments of processing information into memory and this site holds that it is the most important consideration in memory. Initial encoding is determined by the intensity of the attention payed to the information, which maximizes the storage strength of the memory, and the breadth of the attention payed to the information, which maximizes the amount of detail remembered. Intensity and breadth of attention are good if we want to retain the memory but not so if we wish to forget the information. 

Subsequent elaborate encoding. Or elaborate encoding can be further elaborated with each successive retrieval of the memory. This additional information added at the time of retrieval can be good if it comes from accurate sources such as when we are studying or we get an alternative view of the same incident from different observers. But it can also lead to inaccuracies where one memory is mixed with a similar memory, or where information that is itself not accurate is added. For instance, false memories or bits of memory can be imported, such as when someone tells us we experienced something, and we come to believe it although it never happened.

The impermanence of memory.

There have also been theories about whether all our experiences and knowledge are permanently recorded in our brains. Are they there, and we are simply not able to find our way to them each time we need them, or do memories decay and get deleted. There are in fact two quite different theories about how recall happens. Here are two explanations from John Medena’s book ‘Brain Rules”.

Retrieval of memories. John Medina in his book "Brain Rules" points out that retrieval of memories is  conceived of as happening in two different ways, the library model and the crime scene model.

1. Reproductive retrieval. John explains the library method of retrieval as follows: "In the library model, memories are stored in our heads the same way books are stored in a library. Retrieval begins with a command to browse through the stacks and select a specific volume. Once selected, the contents are brought into conscious awareness, and the memory is retrieved. This tame process is sometimes called reproductive retrieval."

2. Reconstructive retrieval. John explains the crime scene method of retrieval as follows: "The other model imagines our memories to be more like a large collection of crime scenes. Retrieval begins by summoning the detective to a particular crime scene, which invariably consists of a fragmentary memory. Upon arrival Mr. Holms examines the partial evidence available, Based on inference and guesswork the detective then invents a reconstruction of what was actually stored. In this model, retrieval is not the passive examination of a fully reproduced, vividly detailed book. Rather retrieval is an active investigative effort to recreate the facts based on fragments of data."

The decay and muddling of memories. 

Although current science holds that we use both these systems it is more generally accepted that recall mostly takes the form of reconstructing from clues. Also it is fairly clear that long-term memory is retrieved mostly by reconstructive retrieval. In fact really accurate, detailed, reproductive retrieval is usually believed to only be good or even possible for a few days. It seems more likely, however, that these two systems are simply separate aspects of the same system. When we recall a memory that network of connections becomes active as an electric impulse runs through it. When this occurs the connecting fibers, the axons, get coated with myelin. This does a number of things. It allows the impulse to travel faster next time and it protects the neurons from damage. Thus the more often a memory is recalled the more protected it is and the less likely it is to become damaged. On the other hand if a memory is not recalled it will tend to weaken and become inoperative as the synapses that connect to other neurons appear to wither and die. There are several possible ways in which memories might be damaged which would necessitate the need for a reconstruction process in recall. Thus unrecalled memories are much more likely to become damaged or even deleted over time.

This site holds that we should not be surprised by this state of affairs. We should expect memories to become damaged or partially forgotten over time. We should expect bits of information to become lost. We might expect input of a particular sense to disappear out of a particular memory. We should expect bits of information to be deleted by the brain because it is not used or seems unimportant. We should expect memories to become mixed with other similar memories. We should expect the brain to insert made up information into old damaged memories in order to make them make sense. Of course as explained earlier on this page, the more memories are used, the better the chances of it surviving mostly intact over time, other than massive damage to whole areas of the brain. On the other hand mere recall does not prevent memories becoming mixed up or added to by the very process of reproductive retrieval. Everything appears to break down over time why not memories? It has been found, however, that memories reactivated over spaced periods of time tend to prevent this deterioration from occurring or at least slow it down.

Consolidation of memories. Remembering and forgetting are part of the same process. Consolidation of memory is also about distortion and loss.  John Medina in his book "Brain Rules" explains consolidation as follows:

Possible reasons for the need of reconstructive recall.

Memories get lost. There are many possible ways we can lose memories.

Memories or parts of them may be suppressed so they can be improved. This can require reconstruction if the process needs to be reversed.

Memories can simply fade as part of natural attrition.

The brain can be damaged causing memories or parts of them to be erased requiring reconstruction.

Parts of memories can disappear because those parts are not remembered.

Suppression as both improvement and damage.

Suppression takes place because inhibition allows forgetting in order to improve memories. Suppression is how the brain replaces one memory or part of a memory with a new superior memory. Suppression then is an essential function of learning. A signal is sent usually by the executive parts of the brain located mostly in the prefrontal lobes that suppresses a memory so that it does not activate in circumstances where it previously did. An old theory about the world is suppressed so that a newer superior theory can be activated instead. An old habit is suppressed so that a newer better habit can be activated instead. An old action is suppressed so a newer faster, cleaner, smoother action can be activated instead. Sometimes these inhibiting signals can be used to suppress painful memories which psychologists call repression. Painful memories of this sort are not usually lost because they have strong emotions attached. However, other memories like old theories, old habits, and old actions will gradually weaken and die, because of their lack of activation over a long time. During that time the old memories can still be accessed because they are not gone just suppressed. Sometimes it is necessary to revive such old memories such as when going to a country where they drive on the left after driving on the right for a long while. Although memories may seem to be lost through this suppression, they may be recoverable through reconstructive retrieval if they are not severely damaged.

Natural attrition as damage.

Forgetting as a massive spam filter. Attrition type forgetting's purpose is to prevent bad changes which produce faulty memories and help produce good changes that produce accurate and detailed memories. The problem is that the more memories there are, the more difficult they are to find. Just as spam fills up your email and makes finding useful email difficult, the more memories there are, the more difficult it is to find what you are looking for. Also the more memories there are, the more they tend to overlap and leak into one another. The more memories there are, the more likely there are to be similar memories. The more similar memories there are, the more easily they can be confused with one another and the more easily they will bleed into one another. Forgetting, by reducing the number of memories sharpens the differences between memories thus preventing memories bleeding into one another. We tend to forget those memories that have little emotional intensity attached and those we have no occasion to recall. Our brains work on the assumption that memories that do not have strong emotions attached and or are not recalled often must be unimportant. This means if we do not recall something the memory will tend to wither and die unless it has strong emotions attached. Despite that if a memory contains a lot of elaboration there is a good chance it be recalled in the future even though it has not been recalled for a long while. Forgetting depends on both recall and the likelihood of recall. Memories lost through this kind of attrition can be recovered if only parts are lost by means of reconstruction from clues residing in the bits of memory that are left. This should work better than for brain damage as the clues should be better and more abundant. 

Pruning and strengthening memories while we sleep. The process of forgetting to happen while we sleep. There seem to be two memory processes that occur while we are asleep. One is that some memories are selected to be rerun while we seep, and so improve all the connections within them and thus improve their chances of recall. The other process seems to be that some memories are selected to be deleted (presumably because they have weak connections, few connections or that seem not meaningful or significant). This is a bit like taking out the garbage. In this way whole but unimportant memories disappear every night (a kind of synapse pruning). Basically our brains try to separate the wheat from the chaff while we sleep making one more memorable and purging the other. It is also possible that this sleep pruning of synapses might simply prune parts of memories the parts not recently recalled or not often recalled. This would leave memories with holes in them that would need reconstruction.

Entropy as damage.

Brain damage as forgetting. If a brain is damaged, not only can how a brain works change, but memories or parts of memories can simply be erased. Parts of the brain such as the cortex and the hippocampus which are involved in memory are obvious areas that can cause memory loss if damaged. Information lost in this way can be recovered, if it is only a part memory, by reconstruction based on clues left in the remaining information. But loss caused in this manner can greatly change memories especially as new information is added with each recall.

Naturally occurring phenomena. There are many ways that naturally occurring phenomena might induce memory damage. There are all the ways that brain matter is susceptible to damage over time. There are malfunctions like strokes, virus invasions, chemical imbalances, lack of oxygen and of course blows to the head and actual penetration. Then there is a kind of random entropy caused by neuron weakness or mutation. Fortunately with most of this kind of damage it is only partial (affecting only parts of memories) and thus most of the memories can be reconstructed using the reconstructive sort of recall. Also this kind of damage would be more likely to become worse over time. In this way, recent memories would tend to be far less damaged than long term memories, and thus far less likely to need much reconstruction. Long term memories, on the other hand, would tend to be much more damaged and much more in need of a great deal of reconstruction. This ties in with the fact that the memories, that are recalled more, are better protected from damage.

incomplete recall as damage.

The gist of it. Another way memories might become damaged is the fact that, when we recall a memory, we tend to only recall as much of it as we might need, for whatever it is that cued the recall. In fact, it could be said, that when we recall a memory, we usually only recall the gist of the memory, the important and significant features of the memory. In this way parts of the memory are often not recalled and thus the synapses holding them together could wither and die. This would leave holes in the memory. However, with this kind of loss, the main structure would remain intact, making it easy to reconstruct the memory from clues.

Memories are a bit of a catch 22. On the one hand, if we don’t recall memories they tend to wither and die, but on the other hand, if we do recall them they are likely to become contaminated by new information. Every time we recall a memory new information is added to that memory, and if it is recalled using reconstruction it can become distorted, if the wrong bits are chosen for the reconstruction.

Filling in the blanks.

How do brains reconstruct memories? Well, actually this is something our brains are especially good at. For a start our brains are continually filling in a hole on our vision called our blind spot. It is also constantly turning what would be still pictures into something that constantly moves. This is why video and moving pictures work. Our brains do the same thing with memories, they do what they do best, they fill in the blanks with their best guesses. Our brains fill in the blanks in our memories with bits from (presumably) similar memories. This is not, of course, a perfect process and our brains can and do make mistakes. Obviously similar memories tend to get mixed up and are often become consolidated into a single memory. Dreams get mistaken for memories, stories people tell us can become memories or parts of memories. Indeed how our brain selects information to fill in the holes in our memories may explain how humans end up with so many false and distorted memories.

Memory sets.

Each memory is connected to other memories especially similar memories. Each memory has to make sense internally and also in terms of those other connected memories. How the bits selected to fill in the blanks are chosen probably comes down to what seems to fit, what seems to make the most sense, what provides the most meaning. The memory has to make sense, not only within itself, but in terms of those connected memories. A memory’s very existence may depend on it making sense with those connected memories. In fact sets of memories may also be damaged by the deletion of whole memories and thus may in turn prompt the brain to fill in those blanks with whole new memories.

Just as most of our memories are probably reconstructed using clues left in damaged memories to select similar bits from other memories that seem to fit into the blanks and make sense, so too can other elements seem to fit and make sense. This brain function is not a conscious act. It is unconscious and can be mistaken in ways not likely in a conscious brain. 

The malleability of memory.

Particularly with episodic memory we are forced to concede that such memories are unreliable. We know that details get changed. We know contextual markers can get changed. Sometimes whole memories get included that never happened. Memories tend to become, not what makes sense logically, but what makes sense to our unconscious brains. Memories are meant to be malleable in this way, again, because of evolution. Cave men did not need to remember specific events so much as, recurring events and dangerous sorts of events. They needed for the world to make sense and be predictable. But as explained before, this brain for predicting ancient times makes mistakes especially in this modern world. 

Implanted or false memories.

When probing for so called suppressed memories therapists have had to ask questions, and depending how questions are asked, they can easily become suggestions. Suggestions are a place that our brains can mine when they are looking for bits to fill in memories and make sense of them. Obviously such suggestions can be both intentional and accidental. 

Leading questions. Some kinds of questions are not allowed in courts in some circumstances partly for the very reason that they may interfere with or distort the memories of witnesses. These are leading questions. A leading question is a suggestion and is added to a memory as we recall it. It becomes part of the memory and can easily distort the memory later if the question part is damaged and it becomes part of the original memory.

The compounding of false memories. False memories can become compounded by the efforts of others to get at the truth. A person who has absorbed a bit of a story, a suggestion, a bit of fantasy or a lie may become trapped by it. Such a memory element can disturb others who are driven to probe deeper to learn more. In the process of doing this they may add more suggestions that also get added to the memory. They may add detail to the memory or even add related new false memories.

Various ways memories can become distorted.

There are many other ways our brains can  select information to fill in the blanks which can cause memory distortion. A story we have heard or read, a lie, a fantasy, or even something we have dreamed, can seem to our brains to make sense within a memory and make sense with other memories. In this way, bits of stories, fantasies, dreams and lies can end up being incorporated as parts of our memories or even whole memories. This is especially true of children who have difficulty differentiating between reality and fantasy, truth and lies. 

 Memory facilitation. 

Facilitation at the time of recall and at the time of imprinting.

Memories can be facilitated by circumstances at the time of imprinting and circumstances at the time of recall. Memories are usually facilitated by circumstances at the time of both imprinting and recall.

Memory facilitation at the time of imprinting.

Memories can be facilitated by circumstances at the time of imprinting in many different ways but all of them depend on the amount of attention being paid to the to the information. These are things that go on in our brains that determine the strength of the links in a memory which in turn make recall more likely. They also determine whether we will remember it in the correct sequence or not. These can be described as initial conditions that prevent memory deterioration.

Salience. What are some of the kinds of links that make memories more meaningful and thus memorable? Of course a person first has to notice something to remember it so salience is a factor.

Meaning aids recall.

However, if there is any one thing that could be said to be essential to remembering it is meaning. If something is meaningful or significant to a person it focuses their attention which makes the memory much more likely to be remembered. But what exactly makes one experience, theory or object meaningful and another not so? It could be a number of factors. Indeed we know a lot of different factors each of which seems to both convey more meaning and also make an experience, a theory or an object more memorable. This site suspects that, not only do each of these things add meaning and thus make memories easier to find or reach, but that it is actually the number of links that provide the meaning combined with the strength of each link. Each link, not only provides more information of a memory, but it also acts as an entry point through which the memory can be accessed. The more links the more access points the more likely the memory will be accesses either accidentally in random thoughts or intentionally in guided thoughts.

The amount of connections and strength of connections as meaning.

This plurality of connections makes sense of the fact that more information, contra to expectations and common sense, seems to make memories more memorable not less. This is called elaborative encoding. Add more links and recall becomes easier. In his book “Moonwalking with Einstein” Joshua Foer points out that it is easier to remember a person whose profession is baker than a person who is named Baker. Even though it is the same word, baker as a profession, has all kinds of associations and memory links that connect to it, while the name Baker does not. Professions are highly elaborately encoded.

Elaborate encoding. So, in memory, more associations means a memory is easier to find. When a memory is formed it forges links or associations with many other bits of information in our brains. This is called elaborate encoding. John Medina says "The more elaborately we encode information at the moment of learning, the stronger the memory. ...The trick for business professionals, and for educators is to present bodies of information so compelling that the audience does this on their own, spontaneously engaging in deep elaborate encoding." While associations that enhance the meaning of some memory obviously make it more memorable, other associations the are only peripheral or contextual, but will still enhance memory retrieval because they provide more links or handles for opening the memory. The more associations of any sort added to a memory the easier it is to remember. It follows then, that the more interesting something is, the more associations are added effortlessly and automatically to it. Makes you wonder why things are so boring at schools doesn't it.

Strong emotions aid recall.

The next most important of these conditions is strong emotion. Memories tend to be much more resilient (have strong links) if the memories are connected with a strong emotion. Strong emotions linked to memories such as fear, horror, disgust, surprise, joy and awe tend to rivet our attention, forge strong links, and make memories so vivid that our minds are drawn back to them again and again. These emotions make memory recall inevitable and forgetting difficult.

The strange, the weird and the bizarre aid recall.

Other things that focus our attention, forge strong links and make memories so vivid that our minds are drawn back to them again and again are a memory’s strangeness, its weirdness and how bizarre it is.

Lewdness, horror, tragedy and humor aid recall.

We are also attracted to certain types of incidents and they are in turn memorable. They are easy to recall, because, as with the things mentioned above, we were programed by evolution to find and remember them. What are they? Look at the media. What is it that fills the Internet? Why it is sex, lewdness and pornography. This is all highly memorable, and even more so, when it is about people we know or think that we do. Thus we find the lives of celebrities filling magazines with gossip and lewd stories about their lives. What about newspapers. They are filled with tragedies, disasters, and warnings of coming disasters. The less reputable papers are full of horrors, the disgusting, the weird and the bizarre and of course sex. All these things we have been programmed to find memorable by evolution. Even humor with its surprises and misunderstandings we are sort of programed to remember. Indeed we have a ravenous appetite for all of these things.

Increased sensory information aids recall.

What else could be a factor? Well we have at least five senses and the more information we receive from each sense pertaining to a memory the better. Each bit of sensory data provides a link. Although evolution has shaped our memories to be mostly visual, connections from other senses obviously help make those memories much easier to access. As explained above every link is a gate or access door to a memory. Information from other senses provides strong links that act as contextual markers or cues or triggers that activate the memories. Smells or odors are well known to be particularly effective in this regard. Taste and touch are also known to be quite good in this regard. Although we use sound for language, we are not well adapted to remembering in it, but it can provide cues or triggers for memories quite well. When it comes to visual sensory data, a written word is not a powerful image. A spoken word is easier to remember but a picture (as they say) is worth a thousand words. However, the best kind of visual image is a moving one. We are much better adapted to notice a moving image and much better adapted to remember it. Ultimately the best kind image to remember is a moving one. You might even say a movie is worth a thousand pictures.

Rhythms, rimes and song aid recall.

On a lesser level we have also created art forms that aid memory. In a play, for instance, each actor has to remember a large amount of lines. The way they do this is, each actor uses what the other actor says, or what is said just before they are to speak, as a cue or trigger to recall and make their line pop into their head. The rhythm in poetry and song and rimes also aid greatly in recall enabling us to remember great long poems and complete songs. Indeed a lot of history, myth and stories owe their very existence to the minstrels and bards that kept them alive when writing was an arduous effort carried on by few.

It has been said that William Shakespeare wrote the whole of 'Romeo and Juliet' in iambic pentameter. This is a simple rhythm often used in poetry where an unstressed syllable is followed by a stressed syllable. This gives the rhythm de dum de dum de dum. Shakespeare used this rhythm a lot in his plays usually when nobles were speaking. This not only made those bits of his play highly memorable but it would also have been very helpful to his actors in remembering their lines. 

Memory systems as aids to recall.

In his book “Moonwalking with Einstein” Joshua Foer explains that the earliest documentation of how memory systems can be used to aid recall was in a book produced in ancient Greece. The book was called “Rhetorica ad Herennium”. These memory skills were attributed to the Greek poet Simonides whose story begins Foer’s book. Even though many books have been written, on the subject since, that have added new systems and insights, the ad Herennium is still considered the bible by memory athletes.

Plato's Phaedrus.

Socrates and other philosophers and thinkers of his time were greatly concerned about the newfangled technology of writing and how it seemed, to them, to make the younger generation lazy at using and building their memories. Plato’s Phaedrus tells the story of the God Theuth and Thamus king of Egypt. Theuth invented writing and then offers it to Thamus as a gift. But Thamus refuses the gift as he believes that writing would make people lazy and that they would forget how to use their own memories.

Socrates felt that young people’s lack of desire to hone their abilities, so that they could remember great masses of information, was a sign of degeneration and that people were becoming poorer less perfect beings. This is much like people worrying today that we can no longer do mental arithmetic, or that people do not remember facts the way they used to, because it is so easy to look things up on Wikipedia or Google when we need them.

What Socrates, and these others, failed to understand, was that without his pupil Plato writing things down most of Socrates’ words would have been lost and we would never have known them. Writing was simply an early form of external memory which humanity has been improving ever since. These external memories are the basis for cultural, social and racial memory which is at the heart of all human progress. 

The place of memory skills in the modern world.

This does not mean that memory skills have no place in the modern world. We still need to retain information in order to become experts in various fields and in order to be creative. Also we cannot live our lives totally dependent on google. What these ancient skills enable us to do is to take control consciously of what we wish to remember. They enable us, to not have to remain at the mercy of ancient evolutionarily created mental mechanisms, that are unsuitable for our time. It turns out that the skills taught in the “Rhetorica ad Herennium” are still useful in the modern world. We have someone to thank for having the temerity to write down these memory skills.

Mnemonics.

Humans have invented many ways to organize information. The first letters of words combined with the alphabet make a good system used in most libraries to find books by author, title, subject or publisher.

First letters and words can be used to help recall also. Used this way they are called mnemonics. My first experience with a mnemonic was while at school. Our maths teacher wanted to teach us the order in which to perform mathematical operations. Her answer was BOMDAS. B for brackets, O for of, M for multiply, D for divide, A for add, and S for subtract. It was the only thing I ever learned from her but its power is such that it pops into my head whenever there is need for it. She also told us if we could not remember it we were a SADMOB which is the same letters backwards. There are in fact two more common mnemonics that mathematicians use. They are PEMDAS parentheses, exponents, multiplication, division, addition and subtraction and BODMAS brackets, orders, division, multiplication, addition, subtraction. 

The down side of memory.

Memory athletes (experts) try to organize a very limited amount of information and often only for a short time. This seems to be because the secret of memory is in finding the memories you want when you want them and not in keeping all your memories. Savants such as S and Kim Peak often had problems interacting with the world because their brains were continually getting sidetracked into memories that they do not need or want to recall. Having a great memory, for these people, seems to be more of a curse than an advantage. 

Memory systems.

Working memory.

Remember working memory can only deal with a small number of items and must rely on chunking to create memories with large numbers of items. This is essential to any memory system.

Image and spatial memory.

The other main ingredients of a good memory system come from two notable facts. We humans have very good memories for images and we have very good memories for spatial relationships.

All of us have in our heads an enormous library of paths. We know our way through all the rooms in our houses. We know how each room looks and we use the objects in the rooms as landmarks to enable us to navigate our paths though the house. We have in our heads the maps of thousands of streets and we know our way along them by means of the many landmarks we have memorized along the way. We know well the place where we work. We know the rooms and the doors and how they relate to each other. We know where we go shopping all its ins and outs and the paths we will travel though the shopping area. Many of the shops and signs are landmarks that we use to navigate those paths. We store all these maps and landmark relationships in our brains without much apparent effort

When it comes to images we have an equally large library of these stashed away in our brains. Just think of all the images you can recognize and identify. Not only that, but if we see a group of images, we can pick out the ones we have seen a bit later. If we are presented with a mixed group of images, half of which we have seen before and half we have not, it is easy to pick out those we have previously seen.

In his book “Moonwalking with Einstein” Josh Foer relates how he and some other learners were presented with thirty images that appeared and disappeared very quickly. They were then asked to identify them in a group of mixed images twice the size. They surprised themselves by all identifying all the images correctly. They were then told that they would have done nearly as well if they had tried to identify ten thousand images. Indeed an experiment was performed in the 1970s where researchers asked a group of subjects to do just that. The subjects were able to identify over 80% of the images that they had seen.

Evolutionary optimization of image and spatial memory.

Evolution has shaped humans to desire high calorie foods like sugar to supply energy needed for bursts of fast movement in escaping danger, and desire a lot of it, because ancient man lived in a world of scarcity. We now however live in a world of abundance were sugar has become poisonous. Our bodies were similarly shaped by evolution to produce these bursts of high energy maximum effort exercise, but we now live in a world where we watch TV and spend most of our time sitting in front of a computer.

Unsurprisingly, how our memories work, has also been shaped by evolution and that early harsh environment. Because of our evolutionary beginnings our memories are optimized for the recall of images and spatial relations. Early man needed to recall images of both dangerous and useful objects. Early man also needed to know where those objects were. He needed to know how to find some and how to avoid others.

Connecting images to what we want to remember.

So we can remember spaces and images and chunking helps us layer, these chunks of memory, one inside the other. Memory systems take advantage of all this. But for a memory system to work, we have to somehow connect, each item we want to remember, to an image. There are many ways to do this, and a lot depends on the type of items we are trying to remember. Memory athletes usually try to remember things that are not easy to remember such as numbers or words or playing cards. If you want remember a list of words you can use images that are suggested by the words. However, if you might want to remember a passage or quote from a book you will find that many of the words (like ‘the’ and ‘are’, indeed all these) do not suggest images. For numbers you can just pick images at random and connect them by brute force of imagining them together over and over. For a pack of cards some images might suggest themselves but many would need the same brute force.

Memory palaces.

A memory palace is a system that uses both our abilities in remembering images and our ability to remember places and spatial relations within those places. A memory palace does not have to be a palace or even palatial. It just has to be a place we know well. It can be a house, a street, a shopping center, some people have used the stops along a railway line, and at least one person has used his own body parts making himself the palace.

The way a palace works is, first the items to be remembered are each connected to an image. Then you create a mind palace in your mind. In Foer’s book he describes his first attempt where he used, as a palace, the house of his youth, a house he knew very well indeed. He then took the images he had prepared and stashed them one by one in different places (rooms) in the house as he proceeded through it. To remember the images, and thus the items they were connected to, all he had to do was retrace his steps through the palace. To his surprise the items popped into his mind as he did this.

The major system.

One system for remembering numbers, which is talked about in Foer’s book, is the major system. It is and effective system but it is a poor system to use in competition because it does not work well with very large numbers. The system is simple however. Each single number (0-9) is allocated a letter. They should all be consonants. In this way every two numbers become two letters. Two consonant letters, of this sort, will suggest a word which can be transformed into an image. But you see the problem. The images would only give you two digits plus two digits (and so on) to put in your memory palace. With such a system it is difficult to quickly build up a very large number.

The PAO system.

A better system is the PAO system. PAO stands for person, action, and object. To create a PAO system you first have to memorize 100 images and link each of them to all the two digit combinations from 00-99. Each image has to be of a person performing an action on an object with no duplicate of person, action or object. Thus you have 100 images linked to 100 number combinations. You then create a new image that represents 6 digits. You do this by taking the person from the first two digits, the action from the second two digits, and the object from the last two digits, thus creating the new image. At this point you can already remember 6 digit groups. Memory athletes have found when dropping these images off in their memory palaces they can drop them off 3 at a time at each location (loci) and still remember them quite well. So here we are in our memory palace. We have placed three images at the door and we have 6+6+6=18 digits securely deposited and we have only just entered the hall. So now we are dropping off 18 digits at a time as we proceed through our memory palace. When we have filled each room with 3 images each we need only to retrace our steps through the palace to conjure up very long strings of digits indeed. This kind of system has few limits, and does not end there. A person may be able to learn 1000 images and thus begin with 3 digit groups. Also a mind palace can have as many rooms as you might like. A real palace can be a very big place. The only problem is our need to be familiar with it. Perhaps you could use the building where you have worked if you have explored it sufficiently and are familiar with it.

Of course with Sherlock Holmes what is implied is an overall system. For this you would need to build a super memory palace. You could then shrink down each of your other mind palaces linked to an image and drop them off one by one (or three by three) in the rooms of your super palace. This site has not come across an instance of anyone doing this, but it does not seem impossible.

In designing these person, action, object images, it is best to keep in mind what makes an image meaningful and thus memorable. Remember you are trying to make each image so extraordinary and surprising that it requires no effort to remember it. You will find sex and the bizarre may be your biggest allies in this. However, heed this word of caution. Josh Foer found that using his family members as characters in his PAOs made them far easier to remember, but when his grandmother ended in lewd and lascivious behaviors, he found it very disturbing. He had to remove grandma.

Focus and attention aid recall.

All the above ways of facilitating recall have many things in common. They all increase the number of links to a memory they, all increase the strength of the links  within and to a memory, they all increase the amount of meaning in a memory, and they all focus our attention on that memory. All these things can also be accomplished by an act of will. It can be accomplished through effort full attention at the time of imprinting. The person endeavors to pay attention and thus remember something. This may be interpreted as follows: If we pay attention various associations are formed between this incoming information and information already residing within our heads. These associations give the new information meaning. However, if one tries to accomplish such memory imprinting through making an effort to pay attention, one will tend to fail after about ten minutes, depending on how boring the information is. On top of this, effort full attention is easily scattered as we are lured away by sufficient distraction.

Effortless attention, automatic processing. 

On the other hand interest can focus attention automatically and effortlessly. This in turn causes elaborate encoding to be automatically imprinted as memory and can cause memories to be revisited likewise effortlessly. We do not have to use effort full attention to focus, we are instead focused by our interest. In his book "Brain Rules" John Medina gives an example of automatic processing where intense associations are formed by means of great emotional excitement as follows:

Types of interest that focus attention. 

This interest that supports effortless automatic processing comes in a number of different flavors.

1. Fight or flight Interest. Interest comes in many forms but the strongest form comes from that brain function that continually scans all incoming sensory data for signs of a threat. This function automatically focuses our attention on anything that might be threatening to us. This kind of self protection interest focuses our attention to enable us to protect ourselves from threat by activating the reticular system that prepares us for fighting or fleeing. In doing this it can produce fear so intense that the memories when imprinted have very strong storage strength and retrieval strength. This has been long known and is the basis for using it in the home and at school to make knowledge memorable. Unfortunately fear, anxiety and worry are used so pervasively both in our homes and in our schools that their effect is greatly diffused and thus diluted. Fear anxiety and worry become defused by being added to almost all learning. By being undifferentiated in this way fear anxiety and worry lose their impact just like too many advertising messages become just a babble of noise. It also has the unfortunate effect of rendering learners continually and permanently anxious. This in turn has the unfortunate side effect of preventing our bodys from repairing themselves due to the high concentrations of the hormone cortisol which prepares us for fight or flight. Cortisol redirects other body resources to enable flight or fight and in the process shuts down the replacement of damaged tissue with new tissue. This all this overuse of fear in learning makes it a very infective emotion in making learning memorable. Fear should be reserved for life and death memories.     

2. Intellectual Interest. Intellectual interest occurs where similar information has brought pleasure previously and thus we anticipate this new information will also bring pleasure, thus focusing our attention on the information. Intellectual interest can produce strong storage strength and retrieval strength but starts out in a delicate easily crushed form. This type of interest is not only very effective but it also becomes increasingly effective the more a particular interest is fed. 

3. Emotional Interest. Emotional interest occurs where some strong emotion rivets our attention on some event or episode. This can also be used as way of re-enabling effort full attention but can also establish effortless attention. All emotions can be helpful in this way to some degree. However, some emotions such as anger, joy, excitement, awe and disgust can attach associations that are highly riveting.

4. Surprise Interest. Surprise interest (curiosity) occurs where something unusual or unexpected rivets our attention on some event or episode. This can also be used as way of re-enabling effort full attention or establish effortless attention. Surprise is of course an emotion but one deserving a special mention and is also linked to reticular activation but with less stress and cortisol release.

5. Humorous Interest. Humor is a kind of surprise. It too can rivet our attention on some event or episode. Likewise it can also be used as way of re-enabling effort full attention. But it is just magic in creating effortless attention. It glues associations to memories with strong retrieval and storage strengths. 

6. Story Interest. Story interest occurs where the information comes in the form of a story. The interconnectedness of a story provides its own way of automatically focusing attention effortlessly. Stories have been used to imprint memories long before recorded history in the rhymes and songs of the bards.

7. Simple Interest. Simplicity in interest occurs where information has been presented in a compressed form, where the gist of some idea or concept has been teased out and conveyed in an understandable way. The brain seems to recognize this gist as having already performed much of its work and favors it with strong focus of effortless attention. It may also be that the gist has by its very nature many handles on it that connect easily and strongly with many associations to information already residing within our heads. Otherwise it would not be understandable.

8. Prurient interest. Sex, as explained above, is always interesting to humans, and will always automatically focus our attention. It has the power to produce massive storage strength and retrieval strength.
   

Memory facilitation at the time of recall. 

Memories can also be facilitated by circumstances at the time of recall or any form of revisiting the memory. This too depends on the amount of attention being paid to the the information. 

Effort full attention. 

Elaborate encoding can be accomplished through effort full attention at the time of recall. The person endeavors to pay attention, or focus on what is being recalled, relearned or studied. This may be interpreted as follows: when we pay attention various associations are formed between the recalled memory and other information, both new information, and the information already residing within our heads. All these associations give the memory more meaning. Similarly when one tries to accomplish memory improvement through making an effort to pay attention, one will tend to fail after about ten minutes. Also this effort to pay full attention is easily distracted by anything of greater interest. 

Effortless attention, automatic processing. 

On the other hand interest itself can focus attention automatically and effortlessly while we are in the process of recall, or attempting to improve memory storage-strength/retrieval-strength by means of revision, relearning or study. This enables further elaborate encoding to be automatically added as augmented memory. This in turn can enable the same memories to be recalled far more effortlessly at a later date. When we do this, we do not have to use effort full attention to focus, we are instead being focused by our own interest.  

Types of interest that focus attention. This interest that supports effortless automatic processing can also become attached at the time of recall or revision and comes in the same number of different flavors.

1. Fight or flight Interest. Fear, as previously explained, is often used in schools to terrify students into remembering. This pervasive connection to all learning is just as attachable to memories at times of subsequent revision, recall or study. This activation of the reticular system that prepares us for fighting or fleeing automatically focuses our attention on anything that might be threatening to us. Unfortunately what we learn in school is usually not itself scary. The fear that is added as links to a particular memory, in this case, is quite far removed, in some distant future of possible failure. It turns out therefor that it is not a very effective sort of interest to focus attention at the time of recall, revision, study or relearning.

2. Intellectual Interest. Intellectual interest is the most effective interest at the time of recall, revision or relearning. Our desire for more similar information causes new information to be added which both strengthens and clarifys the old information. The more information we have on a subject the more intellectually interesting it is, and the more we want to know about the subject. This in turn strengthens the memory in every way as it becomes more elaborately encoded. 

3. Emotional Interest. Emotional interest for the most part works strongly at the time of first  imprinting of a memory but is less and less effective at times of recall, revision, study or relearning. Not only do the original emotions fade with time but is all but imposible to add new emotions to old memories. The best that can be hoped for is that the orignal emotion is rekindled with each recall and thus does not fade. This can happen with fear, if the initial fear is srong enough, but fear more than any other emotion tends to get supressed especially if combined with pain and suffering. A more likely emotion to be retained by rekindeling with each recalling is strong anger and fury. This emotion may be rekindled with each recalling even when combined with pain and suffering.

4. Surprise Interest. Surprise interest (curiosity) works well to focus attention at the time of imprinting memories but also works very well at the time of recall, revision, study and relearning. The unusual, the strange, the unexpected and the bizarre rivet our attention on some event or experience at the time of recall or study in a way few other things can. 

5. Humorous Interest. Humor too can rivet our attention on some memorized event or experience at the time of recall or relearning. Humor generates effortless attention for revizing already imprinted memories and thus augments the memory and greatly strengthens the learned knowledge. It strengthens both retrieval and storage strengths. 

6. Story Interest. Story interest also greatly helps recall both at he time of original imprinting and any subsequent recall relearning or study. The interconnectedness of a story provides its own way of automatically focusing attention effortlessly any time it is heard or read. Stories have been used as a means to strengthen memories long before recorded history as has rhyming and and the rhythm of songs.

7. Simple Interest. Simplicity in interest is interest, and thus memory, in a compact or simplified form, usually understood to be gist of some event, idea or concept. Although it is often teased out by others for consumption at the time of imprinting it is also teased out by ourselves at the time of recall, revision or study so that we can better understand it and incidently make it more memorable. The gist can also be attached as a link when sudying if a simplified version of the knowledge is accessed as part of studying. When this happens it is possible this simplified form can be substituted for the original memory thus making the memory both simpler and more memorable. Curiously, a memory that has been compressed into its gist has more handles or pathways connecting to it, rather than less, even though they are less srong as they are less likely to be remembered in recall.

8. Prurient interest. Sex, while being an excelent way of riveting our attention at he time of imprinting a memory, is also diverse enough to help focus attention on susequent recall of memories or on the reinforcing of memories by means of revision and study.  

Elaborate encoding while recalling. although memories can be elabortely coded at the time of imprinting they continue to be more elaborately coded with each recall or review. This happens mostly by means of curiosity and interest. Even so some residual encoding takes place even without the focused attention enabled by curiosity and attention. Specifically with each recall or review of a memory we also encode new information. Because most recall involves the reconstruction of partial memories associations are borrowed to fill in for the damage. This new information can be, as explained above, distorting or wrong, but it can also be augmenting and right. Obviously review or study have a much better chance of producing more accurate links but it has been shown that the efort to remember is far more likely to produce stronger memories. When more information is added to the memory during recall it is usually concerning events taking place while the recall is happening. When more information or associations are added later, in this way, those associations, if we are not careful in selecting them, can thus distort the memory instead of just making the memory more memorable. Because of this, care should always be taken when recalling to ensure that any new information added does in fact improve the memory and not distort it or invalidate it.   

Real-world examples focus attention. When a memory is formed or imprinted initially it may, if not presented in a way that is clear to every single learner, be unclear to some people because it does not link up with sufficient knowledge already understood in their heads. The more this linking with other memories, in a brain takes place, the more meaning is gained by the new memory being formed, and the more elaborately it is encoded. Now, as explained previously, we usually tend not to remember examples so much as the gist of the principle, idea, theory or concept. However, despite that, concrete examples of principles, ideas theories or concepts, are immensely important in forming those principles, ideas, theories or concepts. While we are still trying to understand a principle, idea, theory or concept, a more abstract explanation can be almost meaningless. What is needed is some concrete examples to ground the information and thus the memory in the real world. It was once thought that the order in which this learning took place was important, but it now seems that there are learning benefits no matter the order of learning. If we learn an abstact principle it is no better than learning an example of that principle. On the one hand many examples of an abstact principle may lead a person to a good understanding of the principle. Yet if we are presented with the abstact principle and then come to understand it better by subsequently being presented with concrete examples of it working, then our learning may be just as complete and effective. What is clear, either way, is that examples are needed to make a principle, idea, concept or a theory meaningful and thus understandable. It can be partially done at the initial time of imprinting a memory, but it can be just as easily done and to a greater extent at various times of recall and revision of the memory. John Medina explains examples as follows: 

"How does one communicate meaning in such a fashion that learning is improved? A simple trick involves the liberal use of relevant real-world examples embedded in the information, constantly peppering main learning points with meaningful experiences. This can be done by the leaner studying after class or, better, by the teacher during the actual learning experience. This has been shown to work in numerous studies. ...Providing examples is the cognitive equivalent of adding more handles to the door. Providing examples makes the information more elaborative, more complex, better coded, and therefore better learned."

While it may well be, that once a central core concept (the gist) has been formed, concrete examples do not need to be constantly referred to in working memory. Examples, may however, be essential to get to the point where it is possible to transform a memory into a gist. When a gist is formed examples may be able to sink into unconsciousness, from where they are not usually retrieved when the gist is recalled, and are only retrieved when absolutely needed. 

Context focuses attention. When we use effort full attention we focus on the elements we wish to remember and associate those elements to other memories already imprinted in our minds. But this is not all that happens. Other, usually weaker associations, are also formed with any incoming data, even though we may not pay specific attention to it. These peripheral associations form a context for the information to be memorized, which seems to take place on an unconscious level. These peripheral associations, provide extra door handles for opening up memories. These peripheral associations of context are recorded with the actual memory although in a way that usually precludes their being recalled with that memory. They instead provide more pathways to the memory so enabling easier access to the memory or a higher probability of the memory being recalled.

The initial experiment showing contextual associations focusing attention was done by Godden and Braddeley with scuba divers learning or making memories in an underwater environment. It was clearly shown in this experiment that when the memories were tested those who took the test on land did far worse than those who were tested in an underwater environment. Many experiments later it had been shown clearly that this was a general rule. Learn in one environment and you will be far more able to access those memories if you are returned to the same environment. The same result was found with study. Study in one place and you will most effectively recall the information if tested in the same place. But it is more than about environments (its about environmental cues). Any association present while learning or studying can be helpful in accessing the memory. Study with blue gray cards be tested with blue gray cards. You will do better if your instructor is your tester (the tester is another environmental cue). If music is playing while you are learning you will access more memories if the same music is playing. If you are in a particular mood when studying then try to be in the same mood when being tested. If you took drugs when studying take the same drug for the exam. 

This may not seem very helpful, as for the most part, we have no control over the circumstances of where we are tested. However, when we are trying to retrieve a memory we are actually trying to find a path to that memory. Strong cues if they turn up provide quick access to the memory. But contextual associations or contextual cues provide many many paths to the same memory and one contextual cue has a greater statistical chance of turning up when we need it than any strong cue. So if we vary where learn and study we are increasing the number of peripheral associations (context) and thus increasing the statistical probability that some of them will come up. It has been shown in studies that there is an advantage in simply learning or studying in two different locations if one is to be tested in a third location. There was an improvement in recall of 40% for people who studied in two as compared with those who studied in one location. Why? The only possible answer is more associations or cues.

This too is true for any kind of contextual cue. Thus any kind of variance in how we study will increase the probability of producing an association with the memories in any testing environment. Therefore we should learn and study using as great a variety of mediums and environments as is possible. We should take information in an as great a number of senses as possible. Any kind of change in routine will increase the probability of useful associations turning up in any environment. Think of it like this. Change when learning and studying will enable easier access to the information in a changed testing environment.  

Introductions or hooks focus attention and summaries aid recall. In the movie business they say that if they haven't hooked you into the story in the first three minutes of the opening credits the movie will be a financial failure. In any kind of presentation of information the first few minutes are are where you have to grab the audience's attention. Newspapers and magazines use headlines and leads to grab our attention to lure us to read the rest of an article and do so by captivating our attention. Books should also do this. Good hooks produce strong memories. Think of the old military formula for getting soldiers to remember. Tell them what you are going to tell them, tell them, tell them what you told them. The first part of this formula, which is by far the most important part, is a precis, brief or outline used to hook us into what is come and that arrests our attention. The second part is the fleshing out of the information in detail. The last part is a summary that provides a skeleton that can be used as a structure on which to rebuild the information in recall. 

Discussion and reflection focus attention when recalling. A great deal of research shows that thinking about or talking about an event immediately after it has occurred greatly enhances the memory of that event. It enhances the the durability of the memory the accuracy of the memory and how detailed the memory is. John Medina says: "This tendency is of enormous importance to law enforcement professionals. It is one of the reasons why it is so critical to have a witness recall information as soon as is humanly possible after a crime." wow 

Distraction, alternating targets or interleaving aids recall. It had long been thought that any kind of distraction impinging on focused learning would be detrimental to memorizing. Actually it has turned out to be almost essential to effective learning and the assembling of good elaborate encoding at the time of recall, revision or relearning. Like so many common sense ideas distraction has tuned out not to be what we thought, and the idea that it is destructive to memory has turned out to be mostly false.

This is just an example of evolution at work where early homosapiens had to learn in an environment where distraction was the norm and learning without distraction was impossible. We have therefore become adapted to learn best when we are often distracted or when we have to quickly move from learning about one thing to learning about something else. There are many good reasons, however, why changing from learning one thing to learning another might improve learning overall.

1. Firstly breaks. We need breaks when focusing attention and distractions provide breaks. When making an effort to pay attention to something one is only vaguely interested in, one is likely to fail after about ten minutes. John Medina found it very effective to break up his lectures into 10 minute modules of compressed, essential or core concepts. After each module he would woo back the interest of his audience with an example in the form of a story or an example that would arouse strong emotion or surprise. This he found would keep them going for the next ten minutes. Likewise, when studying, it is probably a good idea to have a break after ten minutes, and if possible indulge in entertaining activity during the break to allow relief from focus. 

2. Secondly transfer. Mixing physical skill practice not only provides breaks in attention but has overall memory retention benefits. Although it has always been the case that coaches mixed practice for training in sports to allow recovery periods for various muscle groups it was previously considered to be a limitation in our ability to repeat actions and not as an aid for learning. However, it has now been repeatedly shown that varied practice of any physical skill works far better than focused continual practice in improving skills. Kerr and Booth who first drew attention to this phenomenon with their beanbag experiment (tossing small beanbags onto bullseyes set at different distances) put it like this: "Varied practice is more effective than the focused kind, because it forces us to internalize general rules of motor adjustment that apply to any hittable targets." Goode and Magill looked at practice for long and short serves in badminton and again random learning beat focused learning hands down. Goode and Margill had their own hunch as presented by Benedict Carey in his book "How We Learn": "Interfering with concentrated or repetitive practice forces people to make continual adjustments ... building a general dexterity that, in turn, sharpens each specific skill. All that adjusting during a mixed-practice session ... also enhances transfer. Not only is each skill sharper; its performed well regardless of context, whether indoors or out, from the right side of the court or the left. The general goal of practice is to transfer to a game. A game situation varies from event to event, making random testing the best condition to appraise the effectiveness of practice."

3. Thirdly whole learning. Mixing practice of any sort (not just physical skills) has overall memory retention benefits. Schmidt and Bjork produced a paper in 1992 called "New Conceptualizations in Practice" in which they looked at practice pertaining to motor, verbal, academic as well as athletic skills. In that paper they concluded the following: "At the most superficial level it appears that systematically altering practice so as to encourage additional, or at least different, information processing activities can degrade performance during practice, but at the same time have the effect of generating greater performance capabilities." Carey puts it like this: "...varied practice produces slower apparent rate of improvement in each single practice session but a greater accumulation of skill and learning over time." 

4. Fourthly interleaving. Mixing practice greatly aids our ability to discriminate, which is not only an important type of memory, but is also an important skill we need to use in identifying the cues essential for recalling specific memories. Kornell and Bjork showed in a study that people were much better at identifying an artistic style in painting, if the style had been initially identified in a mixed random group of paintings, instead of being identified in groups each containing only one artistic style. This may be because we discriminate by identifying how styles differ from one another rather than identifying how styles are similar. Bjork and Kornell called this mixing of styles interleaving (a cognitive science word meaning mixing related but distinct material during a study.) 

   Doug Rohrer a high school Math teacher realized that his students were having problems solving math problems, not because they did not know how to solve the problems, but because they were having trouble identifying each type of math problem when it occurred on a test. If the students could identify each type of problem, he reasoned, they would then recall how to solve that type of problem. Rohrer and Taylor conducted their own study and found that presenting problems in a mixed or random group, as opposed to presenting problems all of the same type, improved students ability to identify types of problems and thus improved students ability to solve each type of problem. Carey in his book explains it as follows: "Mixing problems during study forces us to identify each type of problem and match it to the appropriate kind of solution. We are not only discriminating between the locks to be cracked we are connecting each lock with the right key." Rohrer put it this way: "If the homework says 'The Quadratic Formula' at the top of the page, you just use that blindly. There's no need to ask whether it's appropriate. You know it is before doing the problem." 

It is likely that interleaving will improve any kind of learning as it gives us experience with identifying abstract groupings and connecting them with specific memories. Interleaving also prepares us for dealing with the unexpected as is normal in real world experience. Carey in his book has this to say in conclusion: "Mixed practice doesn't just build overall dexterity and prompt active discrimination. It helps prepare us for life's curve balls, literal and figurative."

5. Fifthly the Zeigarnik effect. A student of Kurt Lewin called Bluma Zeigarnik was given a research project by Lewin when he noticed that the waiters, where they were eating, never wrote orders down, although they were always accurate. Yet on being questioned, after the bill was paid, those same waiters could remember almost nothing of the order. It was not a matter of the time as sometimes the bill was paid quickly and sometimes it took half an hour or longer. Although the original idea was to discover if the completion of the task caused the memory to be lost. The research, however, discovered something else. 

   Zeigarnik discovered that the interruptions and distractions in the waiters work actually shocked the brain causing the information to be continually rehearsed in working memory. In his book "How We Learn" Carey explains: "Running still more trials, Zeigarnik found she could maximize the effect of interruption on memory by stopping people at the moment when they were most engrossed in their work. Interestingly, being interrupted at the 'worst' time seemed to extend memory the longest. 'As everyone knows,' Zeigarnik wrote, 'it is far more disturbing to be interrupted just before finishing a letter than when one has only begun.'"

   The Zeigarnik effect simply states that anything that interrupts the completion of a task will increase the likelihood of it's recall and the more disturbing the interruption the more durable the memory will be and more easily the memory will be recalled. 

Difficulty in recall focuses attention on that memory and is desirable. The harder we work or have to work to retrieve a memory the greater the increase in our ability to retrieve that memory again and the more accessible that memory becomes. This has been called desirable difficulty.  

In his book "How we learn" Carey trys to explain how desirable difficulty might work as follows: "When the brain is retrieving studied text, names, formulas, skills, or anything else, it is doing something harder than when it simply sees the information again, or restudies. The extra effort deepens the resulting storage and retrieval strength. We know the facts or skills better because we retrieved them ourselves, we didn't merely review them." Carey also quotes researcher Roediger who goes further: "When we successfully retrieve a fact ... we then re-store it in memory in a different way than we did before. Not only has the storage level spiked; the memory itself has new and different connections. It's now linked to other related facts that we've also retrieved. The network of cells holding the memory has itself been altered. Using our memory changes our memory in ways we don't anticipate."

Not only that but also when memories come easily, attention does not have to be focused, and so we tend to think that a memory will always remain, but in truth the opposite is true. Without focused attention when recalling, memories tend to slip away. Our overconfidence in the permanence of memories we have recalled easily often leads to surprising amounts of forgetting. This overconfidence we tend to have in the permanence and durability of memories is called the fluency illusion. Sure we know the information now but when we are tested at a later date we are amazed to discover the information has evaporated from memory or cannot be found. We simply do not rehearse it enough for it to become part or long term memory storage because it seems so easy to recall.

By trying to remember information, instead of just looking it up, we avoid this fluency illusion because trying to remember forces us to focus our attention. We can then compare what we remembered with what is in our notes and further elaborate the information by correcting or improving the memory, thus ensuring it will be more accurately remembered in the future. Obviously then, trying to remember some item of information and then looking it up is far more effective in improving a memory than simply looking it up.

It should not surprise us that difficulty or working hard to recall should improve memories. After all it is working our muscles hard that makes them grow and tiny fractures in our bones that cause them to grow stronger. Why should the brain grow better and stronger in a different way to any other body part. 

Also the closer we are to forgetting something the harder we have to work to remember it and the more recent a memory the less hard we have to work to remember it. So, the closer we are to forgetting something the more benefit we get from trying to remember it, because we have to work hard to remember it.

So, a good idea to take advantage of desirable difficulty, is to try and recall and reorganize information from memory, before going to your notes when studying. The information you got right, by working hard to remember it and reorganize it into a new form, will become indelibly etched in your brain. What you got wrong or distorted, and then were able to correct later from your notes, will also be strongly etched in your memory. (Indeed recent research now indicates that getting answers wrong on one test may improve those answer memories if corrected soon after testing. This could mean those students who got the wrong answers on one test may remember better for the next test than those students that got the answers right.) Pretests where one takes a test on information before learning the information also works as the mere trying to retrieve an answer that is not in memory somehow prepares the brain to attach emotional intensity and prepared associations or cues to the memory when the information is eventually learned.

When reviewing in this way, is combined with reviewing when we are just about ready to forget, we create a very effective study program. Similar effects can be accrued by being tested or preferably administering tests on yourself.

Also, obviously, self testing can take the form of explaining the learned material to another person. This not only ensures that we work hard to remember what we have learned (which strengthens the memory) but also ensures that the information is internally consistent and compatible with other people's reality. In this way we can explain why teaching is good for improving both the memory and the understanding of the teacher.  

Making use of desirable difficulty these ways is a win win for remembering.  

Strong first impressions build durable and accessible memories by focusing attention. 

The associations formed when a memory is first imprinted is far more important than those formed on the occasions of its recall. Associations formed when memories are first encoded are more intense and have greater breadth. In his book "Brain Rules" John Medina says:

"Introductions are everything. As an undergraduate, I had a professor who can thoughtfully be described as a lunatic. He taught a class on the history of the cinema, and one day he decided to illustrate for us how art films traditionally depict emotional vulnerability. As he went through the lecture, he literally began taking off his clothes. He first took off his sweater and then, one button at a time, began taking off his shirt down to his T-shirt. He unzipped his trousers, and the fell around his feet, revealing thank goodness, gym clothes. His eyes were shining as he exclaimed, 'You will probably never forget now that some films use physical nudity to express emotional vulnerability. What could be more vulnerable than being naked?' We were thankful he gave us no further details of his example. ...If you are a student, whether in business or education, the events that happen the first time you are exposed to a given information stream play a disproportionately greater role in in your ability to to accurately retrieve it at a later date." 

Intervals in recall improve accessibility and durability of memory by attending optimally. When we are trying to make make memories more accessible and durable, such as when we study, we tend to make a long continuous effort. Experimental studies have shown, however, that this kind of binge relearning is not efficient or effective. There are many reasons why this is the case. 

First of all, remember, effort full attention is only effective for about ten minutes at a time. Pushing ourselves to continue to focus on relearning beyond ten minutes without a break is probably counter productive unless interest renders it effortless.

Also, remember, each time we recall a memory its retrieval strength begins to weaken and its storage strength is usually of limited duration after which the memory will be forgotten. The most effective and efficient way to relearn or to study is to wait until the memory is about to be forgotten and then relearn it. This means finding the least number of times for relearning to provide a continuously durable memory. Memories recalled just before being forgotten are greatly strengthened lasting far longer. If, however, we relearn after the memory has been forgotten, this works too, just not as well. If we relearn a long while before the memory is going to be forgotten, we are flying in the face of one of the brains primary functions. When we try to relearn something we already know our brains are resistant. Why should our brains waste time and effort relearning something we already know. Our brains resist and we have to expend even more effort to relearn it. 

Relearning or studying has been said to work best in fixed, spaced intervals. This is not totally efficient, because it does not take the optimum, and increasing, periods till forgetting into account, but it is an effective strategy. This is especially true if it is performed in conjunction with elaboration to form expanding iterative memories. John Medina says: "Deliberately re-expose yourself to information more elaborately, and in fixed, spaced intervals, if you want the retrieval to be the most vivid it can be."  

A number of studies have now been done that clearly show how intervals can be made more efficient in this regard. One of the first solid looks at spacing was done by a 19 year old Polish college student Piotr Wozniak who was trying to learn English. He had lots of other classes taking up his time but he needed a larger English vocabulary to be proficient in all of them. In his book "How We Learn" Benedict Cary presents the following information about Wosniak. "He found that, after a single study session, he could recall a new word for a couple of days. But if he restudied on the next day the word was retrievable for about a week. After a third review session, a week after the second, the word was retrievable for nearly a month. Wosniak himself wrote: "Intervals should be as long as possible to obtain the minimum frequency of repetitions, and to make the best of the so-called spacing effect...Intervals should be short enough to ensure that the knowledge is still remembered."

Cary continues: "Before long, Wosniak was living and learning according to the rhythms of his system..."  The English experiment became an algorithm, then a personal mission, and finally, in 1987, he turned it into a software package called Super-Memo. Super-Memo teaches according to Wosniak's calculations. It provides digital flash cards and a daily calendar for study, keeping track of when words were first studied and representing them according to the spacing effect. Each previously studied word pops up on screen just before that word is about to drop out of reach of  retrieval." This app is easy to use and free. Although apps do not exist for all subjects anyone can do calculations with chunks of data to find optimal study intervals. They always work out to be intervals that are ever expanding. Many studies have been done by both scientists and teachers showing this to be workable for any subject.

In 1993 the Four Bahricks Study appeared. If Wosniak had established minimum intervals for learning the Bahrick family established the maximum learning intervals for lifetime learning. This kind of learning dealt with lists of words many of which would go past the possibility of retrieval. But being relearned after being forgotten was still effective, especially as they made a conscious effort to find new cues for the words greatly increasing the elaboration of each word memory. In his book "How We Learn" Benedict Cary says: "After five years the family scored highest on the list they'd reviewed according to the most widely spaced, longest running schedule: once every two months for twenty-six sessions." The Bahrick's study used fixed space intervals in their schedule, but it seems likely that this type of relearning would also work best with intervals that are ever expanding rather than of fixed length. 

Memories imprinted or relearned through multiple sensory channels are more accessible and durable. All memories are made up of elements of information coming from all of our bodies different senses. If our brain is using the reconstructive method to retrieve a memory, obviously if the memory includes information from as many senses as possible there is a greater chance of the memory being reconstructed in a more reliable manner. There are simply more clues to what the memory was originally. Not only does more sensory involvement mean more accurate memories but again it also creates more pathways to the memory and thus a more durable memory. This is true for both reproductive and reconstructive retrieval.

1. Taste/Gustatory. Compared to most other animals taste in human beings is a very poor sense indeed. While taste can contribute pathways for finding memories and contribute to episodic memory it provides us with very little useful information unless we train our palates. While taste can prove additional information it does not provide a platform that can be used to communicate complete ideas in the way that language and visual media do. 

2. Smell/Olfactory. Smell is the oldest most primitive sense in the brain. Of all the senses it is the only one that is processed directly without first being mixed with all the other senses. As with taste is very poor in humans, providing us with little in the way of useful information. Nevertheless smell provides extremely strong cues for evoking memories. Similarly smell can prove additional information but it likewise does not provide a platform that can be used to communicate complete ideas in the way that language and visual media do.

3.   Audio/Ecoic. Because of language, and the fact that most of what is meaningful to us is necessarily understood and communicated in linguistic form, hearing must be essential in encoding any memory, but especially so in semantic memory. It is especially useful as an extra medium in which very complicated information can be presented and understood. Hearing information as well as reading it basically gives twice the possibility of recalling it.

4. Visual/Iconic. Vision is the king of the senses. In humans visual processing takes up half of the brain's resources. A visual image is better remembered than a sentence about the same thing. Memories that include images have a much better chance of being remembered than memories that do not include images. We remember best through pictures not through written or spoken words. Animated images are better remembered than still images. Vision is the king of the senses because it is possible to get 4 or five times the possibility of recalling some information simply by taking in that informatin in 4 or five different visual forms. You can take it in in the form of writing, in the form of a cartoon or storynoard, in the form of a video or movie or in the form of animation. 

5. Touch/Enactive. Touch is used in two different ways in remembering. We use it in a declarative memory where we can speak about how things felt. Like taste and smell its main use in memory is in awakening memories although it can convey a fair amount of information if we pay attention to it. Touch is also used in the hidden non declarative memories which involve the feeling of body movement, balance, and the feelings in our muscles as they work and perform actions. Touch like visual and audio can provide atleast two other ways in which complete tasks and descripions can be comunicated and thus provide at least two other aditional ways of increasing the possibility of recalling complex ideas. 

Sleep improves memories. Research has now shown that there is a marked difference in both the retrieval strength and the storage strength of memories before and after sleep. Both storage strength and retrieval strength of new memories are improved after sleep. In the early part of a sleep cycle there is a type of sleep called slow wave sleep. During the slow wave sleep it appears that memories from the previous day tend to be replayed and that we experience these as dreams but do not remember them as we usually do not wake during slow wave sleep. This means that some memories are singled out to be replayed and thus made stronger while other memories are pruned away or discarded. It is a known fact that during this type of sleep that some synapses are downscaled while others are reinforced.

Sleep also seems to be essential for building a mental map of what we are trying to learn. We receive the sensory information while we are awake but we are not immediately able to comprehend or understand it completely as initially the information connects with only a limited amount of the other data stored already in our minds. While we sleep and during the early stages of REM sleep our brains seem to integrate the new information with the old information building a structure that fits it all together. This is also probably experienced as dreams. After sleep information is not only better remembered but better understood or comprehended.

As REM sleep continues this process of repaying memories becomes more and more chaotic. As a result the dreams we have in the later REM sleep become more and more disjointed and transitions more and more abrupt. As a result earlier experience is connected and more unusual connections are made and this is thought to be how creative thought may come into being. Creativity comes about by means of totally random connections being formed and again this is experienced as dreams.   

Repetition or Iteration in memory. In his book John Medina makes special mention of repetition as being important in making memories more enduring and stable. This site takes the position that this could in fact be very misleading. It seems as if that this encouragement to repetition could lend itself to activities that are not conductive to memory improvement at all. We are talking about two activities that, though related, are in fact quite different. Both recall and learning can be repeated but never exactly the same way.

Repetition in recall. Repetition in recall could be simply be recalling the information for no purpose, or for the purpose of rehearsing it so it will be easily activated for an exam. How effective this might be in consolidating memory is difficult to estimate. This site is unaware of any studies done to show that memories recalled where an effort is made not to add new information are still effective in making those memories more enduring and stable.  

Iteration in recall. However, there is no doubt that making use of a memory does in fact cause it to be recalled, and in the process, makes the memory more enduring and stable. When we use the information we have memorized to solve some problem or complete some task, the information has to be recalled, but it also links the memorized information to new information in the form of a concrete example of how the information works and how it is useful. When this happens the information becomes hugely more elaborated and yet more clearly understood, as to it how it functions in reality. In this process the memory is changed and for the better. It becomes a better version of its previous self. The memory becomes an improved clearer more understandable iteration of its previous self.

Repetition in relearning. Repetition in learning could be rereading the same information, rehearse the same information, or rewatching the same information. It can be shown that attempting to do this without taking in any new information could be quite detrimental to remembering and actually difficult if not impossible to accomplish. For a start it is boring. And anything that is boring is very difficult to pay attention to. The brain has already memorized this. Why would our brains help us pay attention to information already memorized? Well it wouldn't would it? So here you are forcing yourself to reread information you already know, or listening to a lecture that you have already heard, or rewatching a presentation you have already seen. Is your memory going to become more durable and stable? Well, maybe, if your brain lets any of that information be attended to. But also maybe not. Maybe it just makes the learning task longer more difficult and unpleasant. This kind of effort can be shown to be very similar to where information is taken in without meaning to tie it together and attach it to other memories in our minds. Also there is a great deal of research that shows that this type of rote learning is only effective for very short periods of time after which it is summarily forgotten.

Iteration in learning. The key to repetition is to be found in elaboration which means it is not really repetition at all. If when we reread a text and we learn something new that we missed or misunderstood when we read it previously, surely this makes all the difference. If, when we reread a text, we make new connections, new associations, our interest and attention are easily maintained. The old information is somewhat activated as the new information is connected to it, so it is sort of repeated and sort of not repeated. It is instead extended and enhanced. This is what can be called a memory iteration. Every time the memory becomes active it changes because each time new information is added to it in an iteration. If it was simply repeated exactly there would be no change.

The same is true if we listen to a tape of a lecture we recorded. The second time through we are actually hearing a different lecture. We are hearing the parts of the lecture that we missed when we first heard it. Our attention is not on the old information we have already memorized but on the information we missed and how it fits together with that information already memorized. The lecture comes together better, it connects better with what we already know, and the information we have now memorized is an extended iteration of what we had remembered previously.

Watching a presentation a second time the same process of iteration occurs. When you watch a movie for a second time you should see a different movie. You should pick up on bits you missed. In the same way watching a presentation for a second time you should experience connections to what you have already memorized that you missed the first time through, or experience internal connections within the presentation that you did not connect together before. The memory of the presentation is a both more complex and more simple than it had been previously. It is an improved iteration of its former self.

The memory paradox. The more information there is the better the memory. It seems, at first sight, that more information should be more difficult to remember than less information, but such is not the case. It seems at first anti intuitive. However, once we understand how memory works this does make sense. First of all, as explained above, more information means more pathways that link to the memory and thus more ways of reaching the memory when we are trying to find it. However, it is also true the more information we have memorized about a subject the more that information can be compressed into an abbreviated or symbolic form that stands for that concept or idea. More information also allows larger ideas or theories to be compressed in the same way into core simplifications or gist as John Medina likes to call it. Basically the more information attended to, at the initial exposure, the better and more memorable the memory. Like wise, the more new information added to that memory in subsequent interactions, the more stable and more enduring the memory.

Summary

1. Interest. Any thing that helps create interest greatly improves memory because it enables effortless attention.

2. Use all senses. Paying attention to information coming from many different senses enables encoding to be much more elaborate and thus greatly improves the likelihood of a memory enduring. It also creates many more paths to reach the memory when attempting to recall it.

3. Contextual associations. Attention is not paid to information that does not seem important to the brain, but much of that information is recorded peripherally any way. Most of this peripheral encoding is contextual. When such contexts of initial encoding are recreated they greatly aid recall of that specific memory. 

4. Discussion and reflection. Discussion and reflection are self induced form of recall and any form of recall aids future recall. However discussion and reflection also greatly elaborate any memory making that memory increasingly durable and retrievable.

5. Interleaving study. Evolution created a learning machine in man in a world of constant interruptions and distractions. Is it any wonder then that we learn or memorize best in environments filled with distractions and interruptions. 

6. Desirable difficulty. When we work hard at recalling a memory this greatly improves the durability and accessibility of that memory for future recall.

7. Examples. Concrete real world examples are best for anchoring memorized information in reality, but even abstract examples are useful in elaborating information and thus making it more memorable.

8. The hook. Any informational sequence must coax you into being interested in it by means of its opening data if an enduring memory is to be encoded.

9. Increasingly spaced intervals. Memory is efficiently consolidated if the memory is relearned just as you reach the point of forgetting it.

Conjecture: A tentative theory of how memory might work. 

The information presented above on the surface seems very disconnected but if the conjectural material presented there is taken a bit further it is possible to present a comprehensive scenario of how memory as a whole might work. This site proposes that the following is just such scenario.

New cells form. We are now sure that neurogenesis takes place in the sub-ventricular part of the brain creating stem cells. These seed cells divide and then half of them migrate to the area of the brain that is being used in the new learning. Many of them (perhaps most) travel to that area of the brain called the hippocampus. This site holds that these new cells become, not new memories, but rather sort of anchors through which new memories might form by connecting to various parts of the brain (primarily in the cerebral cortex). The outer edges of the hippocampus is highly connected to all parts of the cortex. This new cell or cells then become a kind of nexus through which all parts of the new memory are connected. Initially these new memories could be understood to be short term memories. 

Become short term memories. If these new (short term) memories were not recalled they would tend to wither and die. If, on the other hand, they were recalled and elaborated further they would tend to become more permanent as they gather more and more myelin over the connections. As myelin builds up it not only enables the electrical impulses to travel faster through the neurons but also protects the neuron from damage. In this way the neurons involved in the particular memory become more resilient as well as being less likely to wither and die. Thus short term memories could wither away or become stronger depending on whether they were recalled and elaborated or not. There is also the possibility that the memory would be only partially recalled and that therefore parts of it could also become damaged or lost. This would not necessarily stop the full recall of the memory but would involve the memory being reconstructed from clues left in good condition in the neuron connections. The more connections existing the more easily and accurately this reconstruction would be. 

Become long term memories. This site theorizes that long term memory is not one single state but rather a succession of different states ever changing and without some final form. There would be two processes going on both of which would be attempting to create a better fasted more resilient form of the memory each time it would be recalled. 

1/ Using existing paths. One process would be trying to find a better, faster, shorter distance, between the various points on the cortex and the newly minted neuron that is acting as a junction box for them. This would emerge because new growths of dendrites and synapses would occur and be activated shortening the distance involved in all the connectors.

2/ Duplicate memory structure. The other process would be trying to create a duplicate of connections to the same points on the cortex but by making those connections through the neocortex just under the cortex. This might involve the elongation of some neurons or new dendrite and synaptic creation. This duplication could take a lot of time because the pathways might have to be created by means of neuron growth. However, as explained above it is also possible this growth could be the result of random synaptic growth combined with an evolutionary survival of the fittest guiding of pruning of unused synapses. In any case it would still take considerable time. In any case, this is very different to the pathways to and from the hippocampus where the pathways exist and simply have to be joined together. It is quite possible that this duplicate memory structure could take many years to complete. While this duplication is taking place the memory would be in a continuing changing state where the memory consists of growing numbers of connections through the neocortex and reducing numbers of connections that travel down to the hippocampus and back.

Memory independence. At some point all connections with the hippocampus would be severed as connections through the neocortex cortex would be shorter and therefor faster. Of course these connections like those going to the hippocampus and back to the cortex would also build up myelin in response to being recalled and or elaborated. Thus the memory would continue to change even after becoming completely disengaged from the hippocampus. This would explain why some old memorys remain even after the whole of the hippocampus has been removed and the brain is no longer able to form new memories.  

Recall. Recall would involve two procedures. It would involve the activation of the existing pathways of the memory and it would also involve a reconstruction process where the brain guesses the part of the memory that had been damaged or had withered and died. It would do this using clues provided by the memory paths that were still intact. This would then be used to connect new pathways to replace the lost ones. The result of course would not be perfect and would allow the memories to be more likely to be corrupted over time. However the more connections or elaborate the memory the more clues that would provide and thus be less likely to be reconstructed incorrectly.

Memory webs. Memories would be, in this scenario, massive numbers of neurons that are linked together either by immensely long axons that connect by growing toward other neurons all existing in the surface of the cortex or by connections via the dense thicket of other neurons that already connect up roughly to cortical areas required. These webs of connexions would be an ongoing ever changing entities. Each recall would cause changes by creating the further elaboration of additional links and reconstruction of missing parts from clues. Similarly lack of recall would also be causing changes by causing parts of the memory to wither and die. Memories far from being stable structures would be continually changing, growing, malleable structures.

Memory and life long learning.

Life long learning ls made possible by certain types of memory. Life long learning is a habit that is prompted by the pleasure experienced when learning and particularly the deep learning of academic subjects where understanding and connectedness to one's map of reality is essential. Memories formed by means of effort full attention tend to be boring and unpleasant and are therefore not conducive to the formation of a life time habit of learning. On the other hand memories formed by means of effortless attention are highly conducive to the formation of a life long learning habit. Memories formed out of curiosity, interest, surprise, awe, and other strong positive emotions are instrumental in building a life long habit of learning.