THE HISTORY OF MEMORY
From the time when man first began to depend on his mind for coping with the environment, the possession of an excellent memory has placed individuals in positions of both command and respect. The amazing feats in remembering accomplished by particular people were so impressive that they have become legendary!
The Greeks
It is difficult to say exactly when and where the first integrated ideas on memory arose. It is reasonable to state, however, that the first sophisticated concepts 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 6th century B.C., Parmenides thought of memory as being a mixture of light and dark or heat and cold! He thought that as long as any given mixture remained unstirred, the memory would be perfect. As soon as the mixture was altered, forgetting occurred. In the 5th century B.C. Diogenes of Appollonia advanced a different theory. He suggested that memory was a process which 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 4th century B.C. 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 moved around on its surface. Once the impression had been made Plato assumed it remained until, with time, it wore away, leaving a smooth surface once more. This smooth surface was, of course, what Plato considered to be complete forgetting—the opposite aspects of the same process. As will become clear later, many people now feel that they are actually 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. When Zeno referred to the mind and its memory he, like the Greeks before him, did not place it in any particular organ or section of the body. To him and to the Greeks 'mind' was a loose and very unclear concept. The first man to introduce a more scientific terminology was Aristotle, in the late 4th century B.C. 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 properly 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 forgetting to be the result of a gradual slowing down of these movements. Aristotle made another important contribution to subsequent thinking on the subject of memory when he introduced his laws of the association of ideas. The concept of association of ideas and images is now generally thought to be of major importance to memory. Throughout Speed Memory this concept will be discussed, developed and applied. In the 3rd century B.C. Herophilus introduced to the discussion 'vital' and 'animal' spirits. He considered the higher order vital spirits to be located in the heart. These 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 man's brain. (these creases are now known as convolutions of the cortex). Despite the fact of his observation, Herophilus offered no reason for his conclusion. It was not until the 19th century, over 2,000 years later, that the real importance of the cortex was discovered. In summary, the Greeks made the following significant contribution: they 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 Surprisingly, the contributions of the Romans were minimal. The major thinkers of their time, including Cicero in the 1st century B.C. and Quintilian in the 1st century A.D., accepted without question the Wax Tablet concept of memory, and did little further work. Their major contribution was in the development of memory systems. It was they who first introduced 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 the progress of ideas on memory was the great physician Galen in the 2nd century A.D. He located and delineated various anatomical and physiological structures, as well as further investigating 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. These spirits he thought were manufactured in the sides of the brain, and it was consequently here that memory was seated. Galen thought that air was sucked into the brain, mixing with the vital spirits. This mixture produced animal spirits which were pushed down through the nervous system, enabling us to feel and taste, etc. 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 on that account little progress was made in the field for 1,500 years. This mental suppression stifled some of the greatest minds that philosophy and science has produced! St. Augustine in the 4th century A.D. accepted the Church's ideas, considering memory to be a function of the soul, which had a physical seat in the brain. He never expanded on the anatomical aspects of his ideas. From the time of St. Augustine until the 17th century there were virtually no significant developments in ideas on memory, and even in the 17th century new ideas were restricted by doctrine. Even such 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 through the brain until they came to the part where memory 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 been said before. He
agreed with Aristotle's ideas, rejecting non-physical explanations of memory. He did not, however, specify the real nature of memory, nor did he make any significant attempts to locate it accurately. In summary, it is evident from the theories of the 16th century intellectuals that the influence of Galen and the Church had been profound. Almost without exception these great thinkers uncritically accepted primitive ideas on memory. Transitional Period—The 18th Century One of the first thinkers to be influenced by the new surge of science and by the ideas of Newton was 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 which began before birth. New sensations modified existing vibrations in degree, kind, place and direction. After influence 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 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. The more often nerves were used, the more easily he thought they vibrated, and the better memory would then 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 more modern theories of memory in the 18th century. The 19th Century. With the development of science in Germany in the 19th century, some important developments occurred. Many of the ideas initiated by the Greeks were overthrown, and work on memory expanded to include the biological sciences. Prochaska finally and irrevocably rejected the age-old idea of animal spirits, on the ground that it has no scientific basis and 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 50 years that localising the area of memory function became a useful pursuit. Another major theory presented in this century was that of Flourens, who 'located' the memory in every part of the brain! He said that the brain acted as a whole and could not be interpreted as the interaction of elementary parts. His views held the field of physiology for some time, and it is only recently that great strides have been made in the development of our thinking on memory. Modern Theories Modern developments in memory 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 cerebum, which is the large area of the brain covering the surface of the cortex. Even today however, the exact localisation of memory areas is proving a difficult task, as is the accurate understanding of the function of memory itself. Current thought has progressed from Ebbinghaus's work with learning and forgetting curves at the turn of the century, to advanced and complex theories. Research and theory can be roughly divided into 3 main areas: work on establishing a biochemical basis for memory; theories which suggest that memory can no longer be considered as a single process but must be broken down into divisions; and Penfield's work on Brain Stimulation. Research into the biochemical basis for memory was initiated by Hyden in the late 1950's. This theory suggests that RNA (ribonucleic acid), a complex molecule, serves as a chemical mediator for memory. RNA is produced by the substance DNA (deoxyrinbonucleic acid) which is responsible for our genetic inheritance—for example DNA decides whether your eyes will be blue or brown, etc. A number of experiments have been performed with RNA, lending support to the idea that it does indeed have a lot to do with the way in which we remember things. For example, if animals are given certain types of training, the RNA found in certain cells is changed. And further, if the production of RNA in an animal's body is stopped or modified, these animals have been 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 which 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'! It is their position 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' from the way in which you recall a telephone number which has just been given to you, and the way in which 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 will probably remain for years, if not for life. Research into direct brain stimulation has been recently initiated by Dr. Wilder Penfield, a clinical surgeon. 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, and conducts, a systematic electrical stimulation of the open brain, and the patient, who remains conscious, reports his experience after each stimulation. In an early case Penfield stimulated the temporal lobe of the brain and the patient reported a recreated 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 recreated 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 to this the stimulated experiences seemed to be far more specific and accurate than normal conscious recall which tends to be a generalisation. It is 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. That brings us roughly up to date! Looking back over history, we see that real thinking in this area has been going on for only a little over two thousand years years, and that for as many as 1,500 of those 2,000 years virtually no advances were made. In fact only a few hundred years of progressive thought have passed, and during those years man has progressed from thinking of memory in terms of spirits and vague concepts, to tracking it down to a fairly small area in the body. But even now he is still only at the beginning of his search. Every month more than 80 new articles are published from the major research centres in the world. It may not be long before final and dramatic breakthroughs are made.
