12 - Memory And It's History
From the time when man first began to depend on his mind for coping with his environment, the possession of an excellent memory has been a step to positions of command and respect. Throughout human history there have been recorded remarkable — sometimes legendary — feats of memory.
The Greeks
It is difficult to say exactly when and where the first integrated ideas on memory arose. The first sophisticated concepts, however, can be attributed to the Greeks, some 600 years before the birth of Christ. As we look back on them now, these 'sophisticated' ideas were surprisingly naive, especially since some of the men proposing them are numbered among the greatest thinkers the world has ever known.
In the sixth century BC, Parmenides thought of memory as being a mixture of light and dark or heat and cold. He believed that as long as any given mixture remained unstirred, the memory would be perfect. As soon as the mixture was altered, forgetting occurred. Diogenes of Apollonia advanced a different theory, in the fifth century BC. He suggested that memory was a process that consisted of events producing an equal distribution of air in the body. Like Parmenides, he thought that when this equilibrium was disturbed, forgetting would occur.
Not surprisingly, the first person to introduce a really major idea in the field of memory was Plato, in the fourth century BC. His theory is known as the Wax Tablet Hypothesis and is still accepted by some people today, although there is growing disagreement. To Plato, the mind accepted impressions in the same way that wax becomes marked when a pointed object is applied to its surface. Plato assumed that once the impression had been made it remained until it wore away with time, leaving a smooth surface once again.
This smooth surface was, of course, what Plato considered to be equivalent to complete forgetting — the opposite aspect of the same process. As will become clear later, many people now feel that memory and forgetting are two quite different processes. Shortly after Plato, Zeno the Stoic slightly modified Plato's ideas, suggesting that sensations actually 'wrote' impressions on the wax tablet. Like the Greeks before him, when Zeno referred to the mind and its memory, he did not place it in any particular organ or section of the body. To him as to the Greeks, 'mind' was a very unclear concept.
The first man to introduce a more scientific terminology was Aristotle, in the late fourth century BC. He maintained that the language previously used was not adequate to explain the physical aspects of memory. In applying his new language Aristotle attributed to the heart most of the functions that we now attribute to the brain. Part of the heart's function, he realised, was concerned with the blood, and he felt that memory was based on the blood's movements.
He thought that forgetting was the result of a gradual slowing down of these movements. Aristotle made another important contribution to the subject of memory when he introduced his laws of association of ideas. The concept of association of ideas and images is now known to be of major importance to memory.
In the third century BC, Herophilus introduced 'vital' and 'animal' spirits to the discussion. He thought that the vital, or 'higher order', spirits produced the 'lower order' animal spirits, which included the memory, the brain and the nervous system.
All of these he thought to be secondary in importance to the heart. It is interesting to note that one reason advanced by Herophilus for man's superiority over animals was the large number of creases in his brain. (These creases are now known as the convolutions of the cortex.) Herophilus, however, offered no reason for his conclusion. It was not until the nineteenth century, more than 2000 years later, that the real importance of the cortex was discovered.
The Greeks, then, were the first to seek a physical as opposed to a spiritual basis for memory; they developed scientific concepts and a language structure that helped the development of these concepts; and they contributed the Wax Tablet Hypothesis, which suggested that memory and forgetting were opposite aspects of the same process.
The Romans
The theoretical contributions by the Romans to our knowledge of memory were surprisingly minimal. The major thinkers of their time, including Cicero in the first century BC and Quintilian in the first century AD, accepted without question the Wax Tablet Hypothesis of memory and did little further work on the subject.
Their major and extremely important contributions were in the development of memory systems. They were the first to introduce the idea of a Link System and a Room System, both of which will be described in later chapters.
The Influence of the Christian Church
The next major contributor to memory theory was the great physician Galen in the second century AD. He located and delineated various anatomical and physiological structures and made further investigations into the function and structure of the nervous system.
Like the later Greeks, he assumed that memory and mental processes were part of the lower order of animal spirits. He thought that these spirits were manufactured in the sides of the brain and that, consequently, memory was seated there. Galen thought that air was sucked into the brain and mixed with the vital spirits. This mixture produced animal spirits that were pushed down through the nervous system, enabling humans to experience sensation.
Galen's ideas on memory were rapidly accepted and condoned by the church, which at this time was beginning to exert a great influence. His ideas became doctrine, and as a result little progress was made in the field for 1500 years. These intellectual strictures stifled some of the greatest minds that philosophy and science have produced. In the fourth century AD St. Augustine accepted the church's idea that memory was a function of the soul and that the soul was located in the brain. He never expanded on the anatomical aspects of these ideas.
From the time of St. Augustine until the seventeenth century there were almost no significant developments, and even in the seventeenth century new ideas were restricted by doctrine. Even so great a thinker as Descartes accepted Galen's basic ideas, although he thought that animal spirits were sent from the pineal gland on special courses could be triggered.
The more clear-cut these courses, the more readily, he thought, would they open when animal spirits travelled through them. It was in this way that he explained the improvement of memory and the development of what are known as memory traces. A memory trace is a physical change in the nervous system that was not present before learning. The trace enables us to recall.
Another great philosopher, who went along with the tide, was Thomas Hobbes, who discussed and considered the idea of memory but contributed little to what had already been said. He agreed with Aristotle's ideas, rejecting nonphysical explanations of memory. He did not, however, specify the real nature of memory, nor did he make any significant attempts to locate it accurately.
It is evident from the theories of the seventeenth-century intellectuals that the inhibiting influence of Galen and the church had been profound. Practically all these great thinkers accepted without question primitive ideas on memory.
Transitional Period — the Eighteenth Century
One of the first thinkers to be influenced by the Renaissance and by the ideas of Newton was David Hartley, who developed the vibratory theory of memory. Applying Newton's ideas on vibrating particles, Hartley suggested that there were memory vibrations in the brain that began before birth.
New sensations modified existing vibrations in degree, kind, place and direction. After being influenced by a new sensation, vibrations quickly returned to their natural state. But if the same sensation appeared again, the vibrations took a little longer to return.
This progression would finally result in the vibrations remaining in their 'new' state, and a memory trace was thus established.
Other major thinkers of this period included Zanotti, who was the first to link electrical forces with brain functions, and Bonnet, who developed the ideas of Hartley in relation to the flexibility of nerve fibres. He felt that the more often nerves were used, the more easily they vibrated, and the better memory would be.
The theories of these men were more sophisticated than previous ones because they had been largely influenced by developments in related scientific fields. This interaction of ideas laid the groundwork for some of the modern theories of memory.
The Nineteenth Century
With the development of science in Germany in the nineteenth century, some important advances occurred. Many of the ideas initiated by the Greeks were overthrown, and work on memory expanded to include the biological sciences.
Georg Prochaska, a Czech physiologist, finally and irrevocably rejected the age-old idea of animal spirits on the grounds that it had no scientific basis and that there was no evidence to support it. He felt that limited existing knowledge made speculation on the location of memory in the brain a waste of time. 'Spatial localisation may be possible,' he said, 'but we just do not Know enough at the moment to make it a useful idea'. It was not for some fifty years that localising the area of memory function became a useful pursuit.
Another major theory presented in this century was that of Pierre Flourens, a French physiologist, who 'located' the memory in every part of the brain. He said that the brain acted as a whole and could not be considered as the interaction of elementary parts.
Modern Theories
Developments in memory research have been aided to an enormous degree by advances in technology and methodology. Almost without exception psychologists and other thinkers in this field agree that memory is located in the cerebrum, which is the large area of the brain covering the surface of the cortex. Even today, however, the exact localization of memory areas is proving a difficult task, as is the accurate understanding of the function of memory itself.
Current thought has progressed from Hermann Ebbinghaus's work, at the turn of the century, with regard to basic learning and forgetting curves, to advanced and complex theories. Research and theory can be roughly divided into three main areas: work on establishing a biochemical basis for memory; theories suggesting that memory can no longer be considered as a single process but must be broken down into divisions; and the clinical surgeon Wilder Penfield's work on brain stimulation.
Research into the biochemical basis for memory was initiated in the late 1950s. This theory suggests that RNA (ribonucleic acid), a complex molecule, serves as a chemical mediator for memory. RNA is produced by the substance DNA (deoxyribonucleic acid), which is responsible for our genetic inheritance.
For example, DNA determines eye colour. A number of experiments have been performed with RNA that lend support to the idea that RNA does indeed have a lot to do with the way in which we remember things. In one instance, when animals were given certain types of training, the RNA found in specific cells was changed. And further, if the production of RNA in an animal's body was stopped or modified, this animal was unable to learn or remember.
An even more exciting experiment showed that when RNA was taken from one rat and injected into another, the second rat 'remembered' things that he had never been taught but that the first rat had.
While research into this aspect of memory is progressing, other theorists are saying that we should stop emphasising 'memory' and concentrate more on the study of 'forgetting'. Their position is that we do not so much remember as gradually forget. Encompassing this idea is the duplex theory of remembering and forgetting, which states that there are two different kinds of information retention: long-term and short-term. For example, you have probably experienced a different 'feeling' in the way that you recall a telephone number that has just been given to you and the way that you recall your own telephone number.
The short-term situation is one in which the idea is 'in' the brain but has not yet been properly coded and is therefore more readily forgotten. In the long-term situation the idea has been completely coded, filed and stored, and it will probably remain there for years, if not for life.
Research into direct brain stimulation was initiated by Dr. Wilder Penfield. In more detail: when performing craniotomies (removal of a small section of the brain) in order to reduce epileptic attacks, Penfield had first to remove a portion of the skull lying over the side of the brain.
Before operating, Penfield conducted a systematic electrical stimulation of the open brain, and the patient, who remained conscious, reported his experience after each stimulation. In an early case Penfield stimulated the temporal lobe of the brain, and the patient reported a re-created memory of a childhood experience.
Penfield found that stimulating various areas of the cortex produces a range of responses but that only stimulation of the temporal lobes leads to reports of meaningful and integrated experiences. These experiences are often complete in that when re-created they include the colour, sound, movement and emotional content of the original experiences.
Of particular interest in these studies is the fact that some of the memories stimulated electrically by Penfield had been unavailable in normal recall. In addition, the stimulated experiences seemed to be far more specific and accurate than normal conscious recall, which tends to be a generalization. It was Penfield's belief that the brain records every item to which it pays conscious attention and that this record is basically permanent, although it may be 'forgotten' in day-to-day living.
More recently, theorists have returned to a position similar to that of Flourens, in which they are suggesting that every part of the brain may include all memories. This model is based on holographic photography. In simple terms, a holographic photographic plate is simply a piece of glass, which, when two laser beams are passed through it at the right angle, reproduces a ghostly, three-dimensional photograph.
One of the amazing things about this photographic plate is that if you smash it into 100 pieces and take any one of those 100 pieces, you can shine the two laser beams through it and still get the same (although slightly more blurred) picture. Thus every part of the holographic photographic plate contains a mini record of the overall picture.
British scientist David Bohm and others are suggesting that the brain is similar. In other words, every one of our multi-million brain cells may, in fact, act as a mini brain, recording in some fantastically complex way, as yet indiscernible to our clumsy measuring instruments, our entire experience.
Fantastic as this theory may sound, it goes a long way toward explaining the perfect memories we have in dreams, the surprise random recall, the memories of the perfect memorisers, the statistics from Rosensweig's experiments, the results of Penfield's experiments, the mathematical grandeur of Anokhin's results, and much of the near-death-type experiences.
Even now we are still on the threshold of a wondrous new world of knowledge, similar to that of the first people who began to explore our planet immediately after having discovered that they could make boats.
How Many Brains?
Supplementing this modern research has been the new discovery that we have not one brain but two. Professor Roger Sperry recently received the Nobel Prize for his breakthrough work in this area. Sperry discovered that each one of us has a brain that is divided into two physiological sections, each dealing with different mental functions.
Sperry has shown that, in most of us, the left side of the brain deals with the following areas:
Logic
Language
Number
Sequencing And Linearity
Analysis
Similarly, in most of us, the right side of the brain deals with the following mental functions:
Rhythm And Music
Imagination
Daydreaming
Colour
Dimension
Take In Artwork
This is your super streamlined brain, depicted as if viewed with X-ray eyes from a vantage point to the left of the left shoulder. Thus, you are looking at the left hemisphere, which deals with the mental functions of logic, language, number, sequencing and linearity, and analysis.
The right side of the brain, the back tip of which you can just see, deals with rhythm and music, imagination, daydreaming, colour and dimension. These two ranges of abilities combine to give you a super powered memory.
No matter what you have been taught, somewhere latent within each of you lies each one of these capabilities simply waiting to be freed. Sperry and others also found that the more people use both sides of their brains together, the more the use of each side benefits the other.
For example, it was found that the study of music helped the study of mathematics, and the study of mathematics helped the study of music; that the study of rhythm helped the study of languages and that the study of languages helped the learning of bodily rhythms; that the study of dimension helped the study of mathematics and that the study of mathematics helped the brain conceptualize dimension; and so on. It was similarly found that if a person used more of these areas, the more generally capable was his entire memory.