By Gregory Mitchell
In Mind Development we recognize the process of memorization has several sequential stages: Sensory Memory; Short-Term Memory; Medium-Term Memory; and Long-Term Memory - with further sub-categories of memory described. This understanding opens many doorways both to improved memorization techniques and to enhanced awareness of our mental processes, and hence the possibility of meta-cognitive control.

Sensory Memory
All incoming information is held briefly (1/2 to 2 seconds) in Sensory Memory as a primitive and unanalyzed copy of the actual sensory information. This storage takes place in the Primary Sensory Cortex, which is why this type of memory is so vivid and lifelike, whilst it lasts.

Auditory (hearing) information is held in 'echoic' memory. To understand echoic memory, imagine someone rattling off a string of numbers, then stopping suddenly and asking you what were the last 5 numbers he or she said. To answer the question, you would have to 'replay' what you had heard. Fortunately, the last few numbers would probably still be in your echoic memory, and most likely you could answer the question correctly. If the person had stopped and waited a few seconds before asking the question, however, probably you would not remember any of the numbers - you could not 'replay the tape.' Echoic memories fade after a few seconds.

Visual information is held is 'iconic' memory. To understand iconic memory, look around you and then shut your eyes. For a short time, you retain a vivid image of everything you just saw. However, as you try to analyze the details, the image fades very rapidly, within 1/2 of a second.

If most of the information in sensory memory fades away and does not get processed further, what determines which information is selected for further processing? Considerable evidence from research suggests that it is the information that we pay attention to that moves on for further processing.

Short-Term Memory
The sensory information's next port of call is the Forebrain. It then becomes Short-Term Memory. The duration of Short-Term Memory depends upon the type of material being stored. Without active rehearsal, numbers are stored for 10 to 15 seconds, but colors are stored for up to 3 minutes.

When you are talking or answering questions on an exam, the information must be brought into Working Memory for you to manipulate, and your words and answers come out of Working Memory. As you try to understand the words on this page, your ability to understand these concepts depends on your Working Memory and also to some extent - when contextual information needs to be retrieved - from your Long-Term Memory.

Short-Term Memory is limited in terms of the both its capacity (amount of information it can hold) and its duration (length of time it can hold information). It is fluid and ever-changing - the focus of our consciousness.

Imagine that you are asked to remember a telephone number that is new to you. You could probably keep it in your memory for more than 30 seconds, but only by saying it over and over again 'in your head.' This is called 'rote rehearsal' or 'maintenance rehearsal.' This can help you to keep information in Short-Term Memory for more than 30 seconds but if anything happens to interrupt your rote rehearsal, the information will be lost, unless you have already succeeded through an effort of memorization to move the information into Medium or Long-Term Memory. You can probably think of real life examples where this has happened: you were trying to keep a telephone number in your head, but someone interrupted your thoughts and you lost the number forever. Or a number where you made an effort to remember it; in our course, we have many methods to help you do this easily.

Our Short-Term Memory at any time contains the information with which we reason. Working Memory is that part of Short-Term Memory that contains the information we use for thinking: visually, verbally and numerically.

The main functions of short-term memory can be itemized as follows:

1. The Articulatory Loop
2. The Visuo-Spatial Sketch Pad
3. The Central Executive
4. Episodic & Semantic Buffers

Not everybody has developed this range of functions to the limit of his ability. Circumstances may have resulted in your developing one faculty at the expense of the others. Development of all these functions, some of which reside in the Left and some in the Right hemispheres of the brain, means that we have to become specialized in these areas. Lack of specialized centers in the brain is called Bicamerality (two cameras), because the functions of the left and right hemispheres are the same and duplicate each other. This results in indecision and other problems of dual personality. Thus there is inefficiency, not only in executive action but in the duplication of information left and right. The primary objective of the Mind Development exercises at this level is to get rid of this Bicamerality, so that your will can be united and your brain becomes a more effective instrument.

1. The Articulatory Loop

The function of the Articulatory Loop is to rehearse speech sub-vocally, that is silently. This is necessary in order to maintain a memory trace as an electrical vibration in the Short-Term Memory. A process of sub-vocal rehearsal is used to refresh a fading memory trace before it decays into inaccessibility. The evidence for the existence of this loop is as follows:

a. Errors in speech often have an acoustic or phonemic similarity, for example F instead of S, B instead of G. It is harder to remember passages with similar speech sounds - the letter sequence of DBCTPG is harder to remember than KWYLRQ, test this for yourself.

b. The effect of articulatory suppression, that is, for example, forcing someone to repeat a common word like 'the' while they are trying to remember a series of digits. This has the effect of reducing the number of digits that can be recalled, i.e. the 'digit span'. These two factors mean that the length and accuracy of the digit span depends upon the ability to rehearse the material sub-vocally.

c. It is easier to remember short words than long ones. Short syllable words like 'bishop' or 'rivet' are easier to remember than words with long vowel sounds like 'harpoon' or 'Friday'. Slowly spoken words are not well remembered. It has been found that digit span levels for Welsh-speaking children are less than those for English-speaking children. This is because the time required to read digits in Welsh is longer. The difference disappears when irrelevant speech sounds are used, and proves that English and Welsh speakers are intellectually equal.

Thus one can say that the efficiency of the Articulatory Loop depends critically on the time taken to say the message, i.e. fast talkers remember better. In short, you can remember as much as you can say in 3 seconds, which is typically the length of the loop. (Our findings are that a child of 8 years speaks at 1.5 words per second and a child of 12 years speaks at 2.5 words per second. The child of 8 has a digit span of approx. 4 and the child of 12 has a digit span of about 7, so this indicates that 3 seconds is about the right figure.)

If I gave you a series of letters to remember, your ability to remember the series correctly would probably depend on the number of letters in the series, which you could 'fit into' the 3 seconds of the Articulatory Loop. Most people can remember a series of letters correctly if there are only 3 or 5 letters in the series. About half the people asked to remember a seven-letter series have difficulty. Relatively few people can remember a series consisting of 9 or 11 letters correctly. This finding, that the limit on Short-Term Memory is typically around 7 items, is one of the most consistent findings in all of psychology. George Miller, a very famous cognitive psychologist, coined the phrase “the magical number seven, plus or minus two,” to describe the capacity of Working Memory.

Working Memory is clearly essential if we are trying to understand a spoken sentence, or remember a string of digits. Working Memory is an active process where the goal is not necessarily to move the information into permanent storage, but to keep it available until it is put to use - think of a phone number you'll repeat to yourself until you can dial it on the phone.

We essentially 'think' out of our working memory, but the capacity of Working Memory is only seven (plus or minus two) items. If the limit on working memory was literally 7 letters, I could not write my own name, much less form a complete sentence. It is true that Short-Term memory has a capacity of 7 somethings, but the limit is not necessarily 7 letters. We can increase the working capacity of Short-Term Memory by combining bits of information into meaningful units, or chunks.

So the memory span of young adults is typically around seven elements, called chunks, regardless whether the elements are digits, letters, words, or other units. However that span does depend on the category of chunks used (e.g., span is around seven for digits, around six for letters, and around 5 for words), and even on features of the chunks within a category. For instance, span is lower for long than for short words. In general, memory span for verbal contents (digits, letters, words, etc.) strongly depends on the time it takes to speak the contents aloud, and on the lexical status of the contents (i.e., whether the contents are words known to the person or not).

A new piece of information may be connected by association with things that we already know or will readily be reminded of, or which are typically linked by logic or character. This connection then forms a single chunk in our symbol space. Many memorization techniques take advantage of this to effectively expand Working Memory.

Focusing on meaning therefore helps with chunking. Understanding the meaning of information to be learned involves understanding how new information relates to other new information or to information you already know.

Focusing on meaning not only helps with chunking, it also helps you to get information into and out of Long-Term Memory in the most efficient way. Repetition in itself is not a very efficient strategy for moving information from Short-Term to Long-Term Memory, but if we focus on the meaning of information to be learned and try to relate it to information that is already in our Long-Term Memory, this seems to help the new information to be effectively filed away. Since Long-Term Memory appears to 'file' information according to meaning, this will also help you to be able to find that information when you need quick access to it in the future.

The Articulatory Loop also appears to be a useful checking mechanism which is good at preserving the order in which information is to be given out. This is particularly noticeable when one is asked to suppress sub-vocalization by saying a word repeatedly under your breath. If two words of a given passage were then reversed, one would be less likely to notice whilst suppressing sub-vocalization. Thus one would use sub-vocalization when reading difficult prose, e.g. a legal document where meticulously accurate comprehension is necessary. But one might not sub-vocalize very much when reading a novel, since the concepts are easy to understand. What one does experience while reading romantic fiction, however, is a mental image of the sound of the characters speaking, as well as a visualization of their surroundings. These 'voices' are not the function of the Articulatory Loop, but of another system which produces auditory and visual imagery.

Visuo-Spatial perception refers to our ability to process and interpret visual information about where objects are in space. This is an important aspect of cognitive functioning because it is responsible for a wide range of activities of daily living. For instance, it underlies our ability to move around in an environment and orient ourselves appropriately. Visuo-Spatial perception is also involved in our ability to accurately reach for objects in our visual field and our ability to shift our gaze to different points in space.

The association areas of the visual cortex are separated into 2 major component pathways, and are believed to mediate different aspects of visual cognition. In humans, the parieto-occipital region is believed to process Visuo-Spatial and Visuo-Motor types of information, dealing with location. Whereas, the inferotemporal region of the brain is believed to mediate our ability to process visual information about the shape, color and texture of objects. The Sketch Pad can be used, for example, for constructing and manipulating visual images, and for the representation of mental maps.

Try multiplying 8 x 13 in your head. You will find that to perform this calculation mentally you will need to 'carry' digits which have to be held over in the memory. To do this you may imagine a blackboard on which you chalk the figures; this then we can define as the Visuo-Spatial Sketch Pad. It is a specialized visualization function of the right hemisphere.

In addition to the visualization faculty there appears to be the ability to hold spatial recording in memory. Blind people are able to find their way about, bats can navigate in the dark by the reflections of the high-frequency sounds they emit, one can learn to touch type without seeing the keyboard.

Words which can be visualized are more easily memorized than those which cannot. It is therefore possible to use visual imagery as a mnemonic system for the purpose of remembering random sequences of numbers and words.

There is evidence that images are stored directly in the brain, which means that information can be accessed rapidly if it is linked to an image, or ideogram, and if perceived material is reduced to these ideograms. This probably does not apply to long-term memory; for reasons of data space the images are converted into an abstract code as they would be in a computer's memory. In order to display and operate upon various images stored in Long-Term Memory we need to have a recall system functioning through codes or keywords. Once the image is recalled to Short-Term Memory it can then run as a program would in a computer, creating the image in the mind's eye and operate upon it.

The ability to visualize is reduced if the subject is asked to point to something while seeing a picture, but heavy verbal tasks, such as grammatical analysis of sentences, do not interfere with the image. If you have ever tried to form a mental picture while driving a car you will realize how dangerous this can be. Nevertheless it is possible to hold conversations with other passengers or listen to the radio without danger. Visual imagery can also be affected by heavy demands upon one's mathematical and logical faculties. Being called upon to make a difficult decision seems to affect the area of executive control necessary to maintain the image.

Spatial memory is an essential part of our ability to function as an individual within our environment. For instance, if I were to walk into a darkened room that was very familiar to me, I would have a good idea where all the individual items in the room were so that I didn't walk into them. In order for me to be able to do this, I need to be able to remember what is in the room and where they all are in relation to my entry point, the door. In short, I need an internal map of the room. The map consists of three elements; what items are present, where they are in relation to each other and where I am, in relation to both those items and the room in general.

The generation and operation of such maps require the integration of multiple neural systems. In order to recognize and recall what is present in the room, two neural systems come into operation. A recognition system based in the Perirhinal Cortex tells me that the items present are familiar to me. A second system that deals with the arrangements of individual items based in the Hippocampus tells me how these items are arranged in relation to each other.

When a person needs to simultaneously perform mental tasks such holding and manipulating data and images, and reasoning with that information, Short Term Memory must allocate available cognitive resources. Short Term Memory is like the control tower of a major airport, responsible for scheduling and coordinating all incoming and outgoing flights. To achieve this, there are the two 'slave systems' described above, the Articulatory Loop and the Visuo-Spatial Sketch Pad responsible for short-term maintenance of information, and a Central Executive responsible for the supervision of integrating the information and for coordinating the slave systems.

The Central Executive is, among other things, responsible for directing attention to relevant information, suppressing irrelevant information and inappropriate actions, and for coordinating cognitive processes when more than one task must be done at the same time.

Here we have a mechanism which is subject to the collective will of the individual, acting on the summation of all desires, needs, motivations and conditioning. This consensus acts as the driving force which powers the Executive and causes it to search endlessly in a closed loop around all the sensory inputs looking for information which can be used in the service of this collective will and to fulfill its aims. It is more like a slave than a master in responding to the whole organism. Freud's concept of the Libido, which was the interaction of creative and destructive forces forms only a small part of the total influence upon the Executive, which acts upon other drives for power and guidance from the Ego and Superego.

Baddely (2002) has postulated a fourth component in the Working Memory, in addition to the Articulatory Loop, the Sketch Pad and the Central Executive. There is a temporary store for information he calls the Episodic Buffer, which holds representations that integrate episodic information (concrete, experiential data) into a unitary episodic representation. This information would include phonological, visual, and spatial information and data retrieved from Long Term Memory.

As yet, the storage location of the Episodic Buffer is not certain, but it is surmised that it may be the Hippocampus, as this would explain a lot of phenomena. In my opinion, the Episodic Buffer acts as a bridge between Short Term Working Memory and the locations of Medium Term Memory and Long Term Working Memory (readily accessible expert information). Medium Term Memory is, for the most part, episodic and temporary, though some of its contents may be stored in Long Term memory if they need to be. Long Term Working Memory is a temporary store of expert knowledge retrieved from Long Term Memory for the task at hand - it is a very much expanded Episodic Buffer.

Recent studies have led to the proposal that Working Memory operates not as a gateway between sensory input and Long Term Memory but as a Workspace. Access to acquired knowledge and prior learning in Medium and Long Term Memory occurs and is integrated in the Episodic Buffer with current sensory input before that complex of information becomes available to Working Memory.

Further research is supporting the existence of a Semantic Buffer, filling a similar role to the Episodic Buffer but for semantic material. The Semantic Buffer is a Working Memory center that stores meaning(s), rather then the surface features of words and phrases. In this way, the theme or topic of an entire discourse may be held in mind, and one may paraphrase or translate to an alternative language. In short, there is a storage buffer for the lexical context of discourse. Current experimental work has suggested that such global structures of meaning play an important part in the cognitive processing of discourse, e.g. in comprehension and recall.

Working Memory
Working Memory is the active system that temporarily stores and manipulates information that is needed in the execution of complex cognitive tasks, such as learning, reasoning and comprehension. Working Memory is all that is currently in view. There are two types of components: storage and central executive functions. The four storage systems within the model are the Articulatory Loop and Semantic Buffer (which are responsible for the temporary storage of verbal and semantic information respectively) and the Visuo-Spatial Sketch Pad and Episodic Buffer (which are responsible for the temporary storage of visual and sensory information).

The Central Executive is very active in Working Memory and is responsible for the selection, initiation and termination of processing routines (e.g. encoding, storing, and retrieving). Encoding refers to the processes of placing items into memory. Retrieval refers to the processes through which we recover items from memory.

Right brain

Left brain

The Central Executive is a limited capacity system used for a variety of purposes, including tasks that involve planning or decision making; trouble shooting in situations in which the automatic processes appear to be running into difficulty; novel situations; dangerous or technically difficult situations; and situations where strong habitual responses or temptations are involved.

Extensive damage to the frontal lobes may result in impairments in Central Executive functioning. The classic frontal syndrome is characterized by “disturbed attention, increased distractibility, a difficultly in grasping the whole of a complicated state of affairs... well able to work along old routines but cannot learn to master new types of task, in new situations.”

An important function of the Working Memory is the ability to store and manipulate numbers. We can recognize similarities, like an 'And' function, we can add, subtract, multiply and divide. Our arithmetical digit span seems to depend upon speed - the faster one can operate with the information stored in Working Memory, the greater the span and accuracy.

Until recently, a person's IQ - a measure of all kinds of mental problem-solving abilities, including spatial skills, memory and verbal reasoning - was thought to be a fixed commodity largely determined by genetics. But recent modern research demonstrates that the very basic brain function called Working Memory in fact underlies our general intelligence, in particular our Fluid Intelligence, opening up the intriguing possibility that if you improve your Working Memory, you would boost your IQ too. This is what Mind Development has found to be the case, over many years experience.

Reasoning ability is central to intelligence. Fluid Intelligence relates to our ability to solve novel problems. Although many different cognitive processes may be executed in the solution of a task, individual differences in Working Memory efficiency, skills and resources play a crucial role in determining the speed and correctness of the results obtained.

Measures of Working Memory capacity are strongly related to performance in other complex cognitive tasks such as reading comprehension and problem solving skills, and with measures of the intelligence quotient. Some researchers have argued that working memory capacity reflects the efficiency of executive functions, most notably the ability to maintain a few task-relevant representations in the face of distracting irrelevant information. The tasks seem to reflect individual differences in ability to focus and maintain attention, particularly when other events are serving to capture attention. These effects seem to be a function of frontal brain areas.

Working Memory is the brain's short-term information storage system. It's a workbench for solving mental problems. For example if you calculate 71 - 7 + 6, your Working Memory will store the intermediate steps necessary to work out the answer. And the amount of information that the Working Memory can hold is strongly related to general intelligence. Of course, writing things down is an important way of extending Working Memory, and this enables organization of information and calculations to be accomplished that would not be possible for most people with information held within the mental space alone. However using notes to extend Working Memory does not exercise and improve the mental ability to hold and juggle a large number of items in the mind, with instant random access to each, as is needed for maximum fluid intelligence.

Recent studies suggest that Working Memory can be improved by training (Klingberg et al., 2002). After training, measured brain activity related to Working Memory increased in the prefrontal cortex, an area that many researchers have associated with Working Memory functions. Perhaps of greater importance, another study has found a period of Working Memory training increases a range of cognitive abilities and increases IQ test scores. Working Memory training - as accomplished, for example, by the memorization techniques included in our Memory Course - is therefore key to unlocking brain power.

I-tags
Within the mind, visual experiences can be distinguished from auditory experiences and from experiences of other sensory modalities. In turn, perceptual experiences can be distinguished from memories, emotions, thoughts, etc. This universal ability implies that certain features of data coming into the field of consciousness can be consciously noted and marked or 'tagged' as such.

Tags are thus seen to form the basis both of phenomenal consciousness and the self. Recently the concept of tagging has been recognized as a fundamental aspect of the creation of memories. Brian Lancaster (in 'Mind, Brain and Human Potential') explains the continuity of the self by means of 'I-tags.' These are the basic data from which our sense of identity is constructed. He proposed that when an event is consciously experienced, its representation in memory includes a reference to the 'I' which actually experienced the event. There is a personal connection and identification with the experienced perception. Subsequent voluntary recall consists of making a connection to the appropriate I-tag. When an I-tag exists there is no effort required to 'find the memory.'

At any given moment, a number of such I-tags are activated, as sensory systems interact with memory. We may intentionally evoke an I-tag or similarity of circumstances may remind us of stored I-tags. Thus I may be using a mouse which triggers one I-tag, sitting at my desk, which includes memories of its purchase, another I-tag, listening to favorite music, another I-tag, and so on. Each I-tag embodies my past identity state when the given entity was experienced previously. The 'I' is continually constructed from an endless flux of I-tags.

Each individual I-tag is the basis of meaning since it embodies the individual's involvement with some specific object or event in the past. It is this 'involvement' - of making an impression with the current sense of self - which makes the difference between experience passing by as a stream, and it's incorporation into our memory storage.

Unless a memory is I-tagged it cannot usually be recalled, it is filed directly into Trash files. Recall will then only occur in the presence of an appropriate environmental trigger (souvenir), or through retrieval by hypnosis. In short, we have to have an I-tag to retrieve something. Mnemonics provide, such a tag.

Medium-Term Memory
From the Forebrain, the remaining material is transferred to the Hippocampus where the consolidation of the material in preparation for sending to Long-Term Memory takes place. The Hippocampus is the storage site of Medium-Term Memory, which is stored for 24 to 48 hours. Medium-Term Memory is a separate system, intermediating between Short-Term Memory and Long-Term Memory. Short-Term storage is electronic, Medium-Term storage is chemical and Long-Term storage is protein based.

Medium-Term Memory is a way station and sorting house where information is stored for a few hours up to 48 hours, in case it is useful. Most of this data is eventually classed as not useful and discarded; the remainder of this Hippocampal content is consolidated and passed on to Long-Term Memory. If we only had a Short-Term Memory and a Long-Term Memory, most of what we have learned would be forgotten in the first two minutes, not over a period of 48 hours or so, where it can be used and evaluated, and the most useful stored for later re-use.

Without Medium-Term Memory, we would not be able to find the car in the evening that we parked in the morning, before we started work. And we would not be able to enjoy a novel, because we would have forgotten the beginning of the page long before we got to the end; we would no longer have a global grasp of the story. Many phenomena are explained by reference to Medium-Term Memory. One researcher suggests that dreams are forgotten within a minute because there is no Medium-Term store, only a Short-Term store, and that unless information is stored first in Medium-Term Memory and reviewed several times, it will not re-file as Long-Term Memory.

Note that Medium-Term Memory capacity can be increased by intensive practice over a long period, for example learning the intricate maps of London if you wish to be a taxi driver, or spending 10 hours every day memorizing the Koran. The Hippocampus has the capacity to grow new cells, if it is used extensively, so the size of the Hippocampus is increased in size, especially the posterior Hippocampus.

The major difference between Short-Term Memory and Medium-Term Memory is that Short-Term Memory content is lost if we switch our attention to another task, but Medium-Term Memory content is not. It is still there when we return to it - material stored at this level is stored for hours. How long it is retained and whether it is then stored for long-term retrieval, depends on how actively we review and refer to the information.

No matter how diligently one studies, no matter how well material seems to have been learned a few minutes after completing the task, it is not long before time begins to erode our memory. An hour later, it may be possible to recall little more than half or even a quarter of what was committed to memory (and far less if no effort was made to pay attention to the material, understand its meanings and inter-relationships, and compare it to existing knowledge). A day later, almost everything seems to have evaporated from the mind, except perhaps for the most stand-out or impressive facts. People forget what they had tried so hard to remember at a rate corresponding to the following graph:

Passive Storage
The curve that represents the rate of forgetting sweeps swiftly downward, showing that only 30 minutes after information has been acquired, a significant amount of the new knowledge is already being lost. For the first 30 minutes, a lot of what we have learned may be retrieved from Medium-Term Memory, but after about 30 minutes, the first stage of consolidation begins so the rate of forgetting becomes rapid. Memory continues to suffer a rapid decline and after 4 hours about 50% of the content has been forgotten, and 90% has been forgotten after 24 hours - or even less if the material had not been properly paid attention to in the first place. Which means we retain at most about 10 percent of the information we hoped to commit to memory - unless a more active process of remembering is adopted.

Active Storage
Material that is rehearsed, because we are actively working on it (e.g. using the information at work) will be reliably stored for several hours and some residue will remain for several days. In the case of Active Storage, approximately 20% to 30% of the material being worked on is transferred to Long-Term Memory. It is impossible to give an exact figure; this depends on how impressionable is the data - its relative importance and emotional coloring.

Even more effective is a regular schedule of review, incorporating key words and key images, to retain 50% or more of the information.

Mnemonic Storage
When Mnemonics using powerful associations and images are made, Medium-Term Memory is 100% reliable for about 4 to 6 hours and about 90% reliable after 24 hours, if there has been no rehearsal of the encoded material. If material is to be available for a longer period and to be 100% accurate, rehearsal must take place. Unless the material in Medium-Term Memory is rehearsed or reviewed several times it will eventually be forgotten. In contrast, if Mnemonics have been used in conjunction with rehearsal - i.e. the information has been recalled, reviewed, actively used, thought about and integrated - most, if not all, of this encoded material is transferred to Long-Term Memory, in which case recall is nearly 100% even after several years. For this reason, techniques for rehearsal of information and techniques for mnemonic encoding, each comprise 50% of our MD course, Creative Memory.

Mnemonics enhance Medium-Term Memory, so unless the material that has been recoded in mnemonic form is reviewed three or four times it will, for the most part, be forgotten. Mnemonics enhance our capacity to duplicate; once we have duplicated a passage or whatever, we can play with it mentally. This mental play, a combination of comparing and contrasting will lead to understanding and once the material is understood it will become part of Permanent Memory.

Our potential for memorization is much greater than our usual practical ability. When the time of exposure to the source material and the time of recall is after only a short delay our recall of the material is almost as great as our full potential, but the gap starts to widen rapidly after as little as half an hour. With suitable prompts, most of the material could be recovered from potential Medium-Term Memory even after several days, although not much longer than that, because true forgetfulness has started to occur - much of the material in Medium-Term Memory is erased after a few days. This is why our recognition span is so good. When we recognize something the thing itself is the prompt. Mnemonics are a special kind of prompt. When we use the formal mnemonic systems to encode material, this material can be recovered even after several days, because the mnemonics act as a series of recognition prompts so the original memory is retrieved. Key Words behave in a similar manner; Key Words act as prompts or triggers, so the original wording of the passage can be retrieved from potential memory.

Why use Mnemonics if, by and large, storage is at the level of the Medium-Term Memory and forgetfulness will occur in three or four days? When used correctly Mnemonics can reduce learning time to about a third. To give you an example, there are forty and some American Presidents since the time of George Washington. Without Mnemonics you would have to rehearse this list of Presidents about 100 times to make a permanent memory. Learning the same list in conjunction with mnemonics would probably take less than half an hour. A memory expert could do something similar in about ten minutes. Okay, you may say, but I will forget this list in about three or four days, because this material is not actually in Long-Term Memory. This is true unless you use rehearsal and connection of the information with your wider knowledge base. If the material is already in Medium-Term Memory, however, you will only have to review it about four to six times to make the memory permanent, so there is a considerable saving in the time taken to learn the list and make it part of Permanent Memory.

Unless you are using mnemonics there is a bottleneck between Short-Term Memory and Medium-Term Memory: many repetitions are required to get the information into Medium-Term Memory. Mnemonics allow a person to overcome this.

Once material is in Medium-Term Memory you will have an illusion that you have learned it; this is not true, it will be forgotten in a few days at most, very little will have entered Long-Term Memory. To transfer material from Medium-Term Memory to Long-Term Memory involves over-learning: it must be repeated several times to make it important enough to transfer to Long-Term Memory and integrated with the existing knowledge base. The important dimension in Medium-Term Memory is how many times have you recalled the material in a meaningful context, not just the number of times you have been exposed to it. If something is recalled several times it becomes sufficiently important to be stored in Long-Term Memory.

Many students cram just before an exam. When they do this, they only have the material stored at the level of Medium-Term Memory. They believe they have learned the material, but they forget what they have crammed soon after the examination.

Mnemonics should not replace understanding unless you are doing party tricks, otherwise there will be little storage in Long-Term Memory. Long-Term Memory operates best with meaningful material.

Semantic & Episodic Memory
Material in Medium-Term Memory is sorted into three categories: Semantic Memory (meaningful information and concepts), Episodic Memory (episodes of life experience) and Trash. The Trash memory is forgotten as far as the conscious mind is concerned, although some of this content may continue to be stored in Implicit long-term storage and have subconscious effects. It may possibly be retrieved by a hypnotist and is the basis for Recognition memory (these mechanisms will be described in more detail later).

Medium-Term Memory is sometimes called Transient Episodic Memory in the literature; this is in fact a good definition, because Medium-Term Memory has a high imagery content, whereas, in contrast, Permanent Memory or Long-Term Memory proper has a large Semantic (conceptual) dimension. For example if you were to go to a lecture, then recall it in the bus on the way home, in most cases this recall would be accompanied by imagery of the lecture, whereas if you were to try to recall the lecture a month later, for the most part your recall would be Semantic: most of the perceptual details will have been forgotten. Contrary to popular belief much of our autobiographical memory is Semantic; we tend to create imagery after the fact, little perceptual imagery is the original perceptions. One exception for many people, however, is the auditory imagery of music. Songs and music, in common with Episodic memory, are stored in the right hemisphere, whereas Semantic memories are stored in the left.

Until the age of about 14, Episodic Memory (memory for events) is predominant. From the age of 14, Semantic Memory (memory for information) starts to play a larger role and by the age of 18 at the latest, Semantic Memory plays the predominant role. During childhood the right hemisphere dominates in most case, but after the age of 18 the left hemisphere is the dominant hemisphere for 90% of the population.

Most adults may have a good recall of events of the last couple of days, because most of the content of Medium-Term Memory is Episodic, but they will tend to have a poor recall of events from last week or last year, because they tend to rely on longer-term Semantic Memory stored in the left hemisphere. They may know that they went to Brighton the week before and they may know they went by train, because this is the usual way to get to Brighton, but they may have little or no memory of the train journey itself, because they are using the more abstract Semantic Memory to reconstruct the episode of going to Brighton, instead of getting in the right-brain mode to relive the experience.

In terms of general intelligence, researchers often differentiate between fluid and crystallized intelligence. Fluid intelligence relates to our ability to solve novel problems and is intrinsic to the functioning of Working Memory. Crystallized intelligence, on the other hand, refers to our accumulated knowledge and experiences and how well we can access and use these, as well as practical intelligence, or the ability to solve to deal with everyday problems and situations. Semantic Memory stored in the left hemisphere is the basis of Crystallized intelligence. Fluid intelligence tends to be negatively affected by age, although this varies among individuals. Crystallized intelligence is generally well preserved and may even improve in some areas in old age, which supports the idea that wisdom comes with age and experience. In my opinion, increases in Crystallized intelligence across the life-span more than compensate for the decrements in Fluid intelligence that occur after the age of forty. The secret of making large increases in Crystallized intelligence is to continue to study until we are on our death bed!

Long-Term Memory
The brain needs to organize complex information in Working Memory before it can be encoded into Long-Term Memory. In this process of organization, the meaningfulness or emotional content of an item may play a role in its retention into Long-Term Memory. If it is considered important, the information will remain in Medium-Term Memory, particularly if one has used memorization techniques such as chunking or mnemonics.

The process of further consolidation in Medium-Term Memory starts after about 30 minutes. From the Hippocampus, the selected memories are passed on to the Parietal Lobes. Semantic Memory to the Left Parietal Lobe and Episodic to the Right Parietal Lobe. During our waking hours some information can be transferred from the Hippocampus to the Parietal Lobes (the first stage of consolidation), but there is little or no transfer from the Parietal Lobes to the Temporal Lobes of the Cortex during the waking state. Further transfer to the Temporal Lobes occurs during sleep. The Temporal Lobes are  the true site of Long Term Memory.

When material is stored in Long-Term Memory, the rate of forgetting drastically slows down; it is as though the information is no longer fluid but has become crystallized. Perhaps 10% of the content is lost in a year and many memories endure for a lifetime. It is the basis of our knowledge base.

For the most part, transfer from the Hippocampus to the Cortex occurs during sleep, and particularly the REM periods. Zhang (2004) proposed that sleep has two different stages: NREM (non-rapid-eye-movement) sleep for processing the Declarative (conscious, recallable) memory, and REM sleep for processing the Implicit (subconscious, unrecallable) memories. He further suggested that there are two types of dreams. The type I dream, a thought-like dream, is the result of the memory replay when the Declarative memory is transferred from the Medium-Term Memory to the Long-Term Memory during NREM sleep. The type II dream, a more 'dream-like' dream, mainly occurs when the Implicit, subconscious memories are transferred from the Medium-Term Memory to the Long-Term Memory during REM sleep.

The capacity of the Hippocampus is finite, it can only store a few days experience at most. Sleep deprivation for as little as four nights is enough to turn some people insane and eight days deprivation will turn most people insane. In addition, recent studies provide compelling evidence that the Amygdala is critically involved in modulating the consolidation of Long-Term memories, and particularly of emotional experiences.

Long-Term Memory stores our knowledge about the world. This in turn affects our perceptions of the world, and influences what information in the environment we attend to. Long-Term Memory provides the framework to which we attach new knowledge - it allows retrieval of information decades after it is stored, and it appears to be essentially unlimited in its capacity.

Schemas are mental models of the world. Psychologists believe that information in Long-Term Memory is stored in large, interrelated networks of these schemas, which form intricate an knowledge network. Related schemas are linked together, and information that activates one schema also activates ones that are closely linked. This allows relevant knowledge to be called up when information is presented.

Long-Term Memory influences what aspects of a situation we pay attention to, allowing us to focus on relevant information and disregard what is not important, which allows our senses to function efficiently.

Long-Term Memory may be divided into Permanent Memory and Long-Term Working Memory. Permanent Memory stores information for up to a lifetime. Once material is in Permanent Memory the rate of forgetting is negligible.

It is beneficial for memorization to connect the items to be remembered to other related information (e.g., elaborating on sentences to be remembered, mnemonic systems, or rhyming). In studying new materials it is best to:

1. Preview the material
2. Make up questions that you will look for answers to
3. Read, trying to answer the questions
4. Reflect while you read. Think of examples, relate it to what you know.
5. Recite or write a synopsis of the information in each section after you've read it. Re-read what you can't recall.
6. Review the major points and the answers to your questions at the end.

Reading, observing and listening are good methods for absorbing data and information into Working Memory. However, this information does not instantly become knowledge once we have absorbed it since it has not been encoded for long-term storage. It can easily become forgotten if it is not accessed for some time or if new information, using the same stimuli and associations, replaces the old. To help make it part of one's permanent knowledge base, one needs to take it through a 'learning cycle' which may include:

• Comprehending and reflecting.
• Forming concepts (models, frameworks, generalizations).
• Fitting it in with previous experience and knowledge.
• Testing in new situations.
• Gaining experience in application.

The speed of recall of information from Long-Term Memory depends in part on how recently that information has been activated and it also depends on the amount of practice, i.e. the frequency and durations of reviews. A well known psychologist and researcher, Ebbinghaus, has reported that each additional recitation (after you have become familiar with the material) engraves the mental trace deeper and deeper, thus establishing a base for long-term retention. For many people over-learning is difficult to practice because, by the time they achieve bare mastery, there is little time left and they are eager to drop the subject and go on to something else. But reciting the material even just one more time significantly increases retention, so try to remember this and utilize the technique when you can.

Long Term Working Memory
In unskilled people the Working Memory is a function of Short-Term Memory and as such it is domain general. Long-Term Memory may also impact on Working Memory in a domain-specific manner. In the case of experts such as mathematicians, chess masters, physicists and people of that ilk, part of the Long-Term Memory has been recruited to create a virtual center that we call Long-Term Working Memory. By and large, this type of working memory is domain specific, in short it has a limited range of transfer. In contrast to the Short-Term Working Memory we cannot view the content all at once. We have an attention window that permits us to perceive 6-10 items or chunks at the same time. The Long-Term Working Memory is like a spreadsheet and the window of attention is a parasitic function of the Short-Term Working Memory.

Long-Term Working Memory is a faculty enjoyed by experts in many fields. Long-Term Working Memory vastly increases the expert's symbol field. It comes into being because the Forebrain parasites on the Parietal Lobes, thus the capacity of Short-Term Memory is enhanced. This is so, because Long-Term Working Memory uses a relevant, fast access area of Long-Term Memory. The capacity of Long-Term Working Memory may be vast, but it is domain specific. There is little transfer to related skills, such as typing and playing the piano; or from playing chess to playing dominoes.

An expert in a given domain of activity, such as medicine, chess, music or golf, is “one, who has acquired special skill in or knowledge about a particular subject through professional training and practical experience” (Webster's, 1976, p. 800). Experts will therefore, by definition, have a greater body of knowledge about their domain of expertise than other individuals.

More remarkable is the expert's accurate memory for new experiences in his or her domain. An elite athlete can, after a sports event, discuss the play-by-play action. Expert chess players can readily recall details of chess positions from their matches in recent tournaments. Early in the twentieth century it was believed that experts were innately talented with a superior ability to store information in memory. Numerous anecdotes were collected as evidence of an unusual ability to store presented information rapidly. For example, Mozart was supposed to be able to reproduce a presented piece of music after hearing it a single time. However, more recent research has rejected the hypothesis of a generally superior memory in experts and has demonstrated that their superior memory is limited to their domains of expertise and can be viewed as the result of acquired skills and knowledge relevant to each specific domain. Although, experienced chess players are better at remembering the positions of the balls on a pool table than novices, so there is a small measure of transfer to related tasks.

The key seems to be the use of mnemonic devices and other methods of imposing some sort of order or meaning on the information involved, such as chunking or grouping into patterns and hierarchies. To illustrate, a chess master can usually recall the positions of all the pieces on a chessboard after a quick glance. But if the chessmen are arranged randomly and meaninglessly, his memory is reduced to near-normal. The gist is that long practice and the application of mnemonic devices can vastly improve anyone's memory and, in consequence, memory prodigies are not really so anomalous.

The Peg System of mnemonics, for example, has much in common with the Long-Term Working Memory system. Material encoded on Pegs is invulnerable to distraction, it may be stored and retrieved, after several hours, with random access and 100% accuracy. A Peg System, such as the Major System or the Memory Graph (which will of course be fully described in Creative Memory), opens up the possibility of reflecting on a hundred or more ideas, rather than the three to five that you can reflect on in Short-Term Working Memory. When Pegs are combined with Short Chains, to make a network of data encoded into mnemonics, their potential for advanced thinking is almost limitless.

Note: Short-Term Working Memory can import ideas (data), three to five at a time, from the Peg System and, in turn, the Short-Term Working Memory can export ideas (data), one by one, to the Peg System.

Long-Term Working Memory is developed as a virtual center by mnemonics experts. Although Long-Term Working Memory is domain specific - a memory expert only has a Long-Term Working Memory for mnemonics - the application of mnemonics is more or less domain-general, so a mnemonics expert gets the best of both worlds.

Intuition is not based on Long-Term Working Memory. With Intuition, you are tapping some sub-cognitive area of the brain, possibly the cerebellum, in which case, you do not know that you know until the answer to your query becomes visible: then you know.

In the case of Long-Term Working Memory, you know already that you know. You know that you have certain items in store, and that you could retrieve them if you wished, and you also know that certain items are not in store, so you can't, in which case, you know you don't know. This is Metacognition. The only content you can actually see is the part that has been imported into Short-Term Memory. At a maximum, only about nine items of data or perhaps two or three patterns can be imported into Short-Term Memory from Long-Term Memory at any one time. Not only do you know what is being stored in Long-Term Working Memory, at any given time, you know, also, where to find any particular item, so you can import any item or collection of items into Short-Term Memory, within Short-Term Memory capacity limitations. Once these items have been imported into Short-Term Memory - but not before - they become visible.

To draw an analogy, Long-Term Working Memory is like a spread-sheet, only part of which is visible at any one time. It is like looking at the spread-sheet through the center of a toilet roll. If you wish to see another area, you have to shift the toilet roll, then you cannot see the area that you were looking at before, but you know it is there and you can return to it any time you want. This is the introspective experience.

In my opinion, little or nothing can be transferred to Long-Term Memory in the waking state, but material from Long-Term Memory can be retrieved in the waking state, and recalled rapidly when the subject has an expert memory in a specific domain of knowledge; so the storage site of Long-Term Working Memory cannot be a department of Long-Term Memory, if the content is to be recalled after a short period: it must be stored in Medium-Term Memory.

Long-Term Working Memory can only store information for a day or two, so it has much more in common with Medium-Term Memory than Long-Term Memory proper; like Medium-Term Memory it functions through the Hippocampus and the Parietal Lobes. The Medium-Term Memory acts as a mixing pot: material from Long-Term Memory is contrasted and compared with information from Short-Term Memory.

Contrary to some popular views, Long-Term Working Memory is not infinite in its capacity. I imagine that it has the capacity to store something in the region of 50 items. Although it has a greater storage capacity than Short-Term Working Memory, it is very rigid and the speed of access is only about half of that of Short-Term Memory. There are also certain things that Long-Term Working Memory cannot do, that Short-Term Working Memory can. Content can only be manipulated once it has been transferred from Long-Term Working Memory to Short. From my introspective experience, the Long-Term Working Memory stores patterns, rather than words and images. Words and images are constructed after the fact.

What one starts with is a sense of knowing. If what it has to show you cannot be put into some meaningful pattern, it will not be available for recall. Because the capacity of Long-Term Working Memory is tied to the recall of accepted and meaningful patterns, it does not much amplify the capacity for creative thinking. On the other hand, Short-Term Working Memory is not subject to these limitations, so anything that can extend the capacity of Short-Term Memory must amplify the capacity both for reasoning and for creative thought.

How long does it take to gain a Long-Term Working Memory? This depends on the domain in question. In the case of a very narrow domain, such as understanding and remembering the weather forecast, this may only take a few weeks. Most intelligent people can already do this, so they already have a Long-Term Working Memory for weather forecasts. But in the case of broad domains, such as becoming an architect, a bishop or a research chemist - or indeed, the meteorologist who prepares weather forecasts - it could take five to ten years. It all depends on the breadth of the domain and the frequency with which Long-Term Memory is accessed in that domain, integrated and used constructively, alongside Short-Term Memory in the Working Memory.

Several different types of memory are included in Long-Term Memory. One way to divide up Long-Term Memory is into Explicit memory and Implicit memory.

Explicit Memory
Explicit memories are memories that we can consciously remember or 'declare' - they are declarative and can readily be restored to Working Memory, i.e. they are consciously available. Most of what we commonly consider 'memory' is explicit memory. Answers you give on an exam are a product of explicit memory. Everything you 'know' you remember is explicit memory.

Episodic and semantic memories are explicit. Episodic memories (stored in right brain for the most part) are personal, autobiographic memories of experience, such as what your first day of school was like, or what you did on your last vacation - it is memory for specific events in time, and may include emotional and multi-sensory data. Medium-Term Memory may also be called, Temporary Episodic Memory.

Semantic memories (stored in left brain for the most part) are facts or meanings, such as names and dates or ideas and concepts. They are fast changing: quick to acquire but also quick to be lost, if unused for a period of time. Semantic Memory is, by and large a product of a literate culture, thus of recent evolutionary origin, whereas in contrast the other types of memory have an evolutionary history of millions of years.

Implicit Memory
Implicit memories are non-declarative - memories that we do not consciously remember, which nonetheless can be show to influence our behavior. For example, the process of conditioning. You may have been exposed to many adverts of a particular brand and taken little notice, but when visiting a supermarket, this exposure may affect your purchasing decision. This is an example of memories that we are not aware of influencing our daily behavior as a result of conditioning.

The Implicit memory system is common to all vertebrates and accounts for associative learning; the Explicit memory system is unique to humans and requires language. The association between a subject and a predicate in language is structurally different from the associations that animals are capable of. Animals can learn associations between stimuli, but cannot infer subject-predicate associations, and that is the prerequisite to acquiring a language. Language allows humans to think in terms of “representations”, of “aboutness”. Animals, who are not endowed with language, cannot grasp this “aboutness”. The “aboutness” relationship is the fundamental grammatical requirement for language.

Implicit Memory is much larger than Explicit or Declarative Memory. These are further examples of Implicit Memory...

Procedural Memory represents motor or skill learning, which is memory without verbal mediation. This type of memory is encoded and probably stored by the cerebellum. It includes learning how to drive a car or tie your shoelace. Such memories are slow to acquire but more resistant to change or loss. Initial storage of Procedural Memory may be in the motor cortex and there is evidence that this storage may last for up to half an hour. The maximum rate of forgetting takes place during this period. Finally, the memory content is transferred from the motor cortex to the cerebellum. When the content has been over-learned it may be stored for a lifetime. One never forgets how to ride a bike.

Remote Memory simply refers to memories that were acquired early on. Since early acquired information is the foundation for new memories and may be linked to many further more recent memories, such memory is less subject to change and/or loss. We have little or no conscious memory of events before the age of two. During the sensory-motor phase of development, between shortly after birth and the age of about two, memory is almost entirely procedural, hence the site of memory storage at that age is the cerebellum. This is why most traumatic material is also stored in the cerebellum: most traumatic events occur before the age of two.

Trash Memories contain information of an episodic nature that was held and used in Working Memory but not noticed significantly enough to tag it for long-term storage. It is not lost, as may appear to be the case, but is passed on to the Implicit storage of Long-Term Memory. It is the basis for Recognition Memory. The Trash file content is not open to introspection except under special circumstances, such as external triggers (e.g. a diary entry, a photograph, hypnosis or deep psychoanalysis) but it has a vast if not unlimited capacity. In addition to the Declarative and Procedural memory systems, the Trashfile/Recognition Memory system represents a third route to Long-Term Memory.

Memory can be categorized in many different ways. One such way to look at your new memories is in terms of recognition and recall (or declarative) memory. These two types of memory simply represent the depth with which you remember the new material. Recognition memory is a superficial memory - if you have this type of memory for a concept, you will recognize the concept when you encounter it and may be able to generate some of the material on your own if you are prompted or given clues. Recall memory is a much deeper level of memory. If you have this type of memory for a concept, you should be able to generate the concept at any time, without any prompting or clues.

Recognition Memory takes effect because of the large implicit recorded memory storage that cannot be recalled voluntarily, but with the correct stimulus it becomes available. This process is called Priming. People can recognize the faces of people shown in pictures if they have seen them before, even if they were long 'forgotten.'

When there is an appropriate trigger, implicit recall may be strong enough to break into conscious awareness and take on the character of Explicit Memory.

Recognition memory can be a trap. This can occur in the area of study among other things. When you come to revise some materials, often you will recognize what you are reading and think that you already know it when actually you do not. The truth is you do not know it and would not be able to answer questions about it, because the information has not been sufficiently deeply processed for encoding to Long-Term Memory to have occurred.

To end on a positive note: without recognition memory life would be extremely difficult, as much of what we do depends upon it. Recollection, as defined by memory specialists, is the ability to call up specific details about an encounter when one is reminded about it, while familiarity is simply knowing that someone or something has been encountered before. Both are elements of recognition memory and both, new research suggests, are functions of the brain's Perirhinal Cortex. You won't run out of space because that organ is estimated to have a capacity of at least 100 billion images!

Creative Memory is in preparation and expected to be released by Spring 2008.

Without memory there is no knowledge, without knowledge there is no certainty and without certainty there is no will. To further evolve, we need to restore and reintegrate our mental processes of expert memorization.