The History of Memory is rocked by attempts at explanations, theories, doubts, and of course, recent advances. We will therefore start from the first reflections of Aristotle and other thinkers of the Antiquity, passing through certain beliefs of the Middle Ages and modern-day thinkers, before ending, as always, by the progresses of the last two hundred years
Aristotle and the ancient vision of memory
To start, it seems natural to evoke Aristotle, one of the most influential thinkers of the Antiquity with Socrates and Plato. In his treatise entitled On the Soul, he tried to define what memory is. He compared the human mind to a blank slate and assumed that men were born without any knowledge and that they are, in fact, only the sum of their experiences. For Aristotle, memory is like a writing that remains etched in wax, and whose inscriptions remain more or less durable.
In Antiquity, the belief was that there were two types of memory: natural memory, which is innate and that everyone uses every day, and artificial memory, which is formed through learning, experiences and memory exercises, which designate exercises to strengthen memory. It was also at this time that these exercises, or rather, the art of strengthening the memory, would be born.
The method of Loci: from Simonide of Ceos to Quintilian, via Cicero
The method of Loci is a perfect example. Although probably legendary, its invention is attributed to Simonides of Ceos, a Greek poet who lived in between the 6th and 5th centuries BC. According to the legend, it all began when Simonide attended a dinner. At some point, he had to suddenly leave the building. At this particular moment, because of an earthquake, the roof of the building collapsed, killing everyone inside. The very lucky Simonide was then called to help identify the bodies. He managed to do so using a particular process. He drew from his memory the exact place where all the guests were seated at the table, and therefore managed to identify them one by one, without exception.
As you may have understood, the method of Loci is a place-based method, which is used to retain lists of ordered elements. It was actually Cicero, a statesman during the Republic of Rome in the 1st century BC, who brought us this story of Simonide of Ceos. Cicero saw in artificial memory a way of developing the intellect and increasing certain aptitudes, such as public speaking. According to him, memory could allow oneself to order his ideas and thoughts optimally. Let’s take the example of a verbal jousting. In order to refute the arguments of his opponent, Cicero assumed that he had to integrate perfectly what his opponent was saying, in order to be able to disassemble his arguments one by one. The art of memory, for a politician like Cicero, was therefore essential. Like Simonide of Ceos, Cicero relied on the method of a place-based memory, meaning he visualized his ideas, represented them, to better remember and use them to complete his speech. Moreover, the poet and pedagogue Quintilian, who lived in the first century of our era, summarized the thought of Cicero in his textbook Institutes of Oratory, written in the year 92: “We must remember what has been said by the adversary, to refute it, not in the same order, but in the most suitable place. […] The talent of improvisation is nothing but a great memory. Indeed, while we speak, we have to foresee what we will say next, and, as the thought is always carried beyond the present moment, all that it meets on the way, it gives it in deposit to the memory and this serves as an intermediary hand, which transmits to speech what it has received from the invention.”
Raymond Lulle and the great art of memory
Much later, in the second half of the Middle Ages, Ramon Llull, who lived from 1233 to 1316, invented an art of memory based on combinations of signs. Llull called himself the “Illuminated Doctor,” because he had, or rather asserted that he had, a divine illumination which asked him to convert ‘’infidels’’. Always in order to better describe his ideas, and thus, in his case, to promote the conversion of non-Christians, Llull laid the foundations of a logical machine. The goal was to have a method to defend and spread beliefs in the most effective way possible. I quote Jean-François Prévéreaud, who in an article on the website Industrie et Technologie explains the principle of Llull’s logical machine : “The theological theories, subjects and predicates were represented under geometric figures on concentric dials, some of which were moved randomly, while others automatically positioned themselves according to the true or false nature attributed to the information they carried. Llull asserted that this machine automatically demonstrated the veracity or inaccuracy of a postulate”. He baptized his machine Ars Magna. What is also interesting about the story of Llull is that as early as the 13th century, people could already understand that human memory, whether innate or artificial according to Aristotle, is not infinite. They started very early to look for ways, tools, to complete human memory. And this research, over the centuries, would eventually give birth to machines, which would lose their initial goal. But we all know these machines today, since you are using them to listen to this podcast.
Matteo Ricci, the Jesuits, and the art of the memory of the great waves of evangelization
In the second half of the 16th century, Matteo Ricci, an Italian Jesuit missionary, developed his idea of the memory palace. To be more precise, during the attempts of evangelization of the Far East, the Jesuits had indeed the idea of developing tools to strengthen memory, based on the ancient tradition, to store knowledge. For these missionaries who went to the other end of the known world, it made the very long journey easier by allowing them to travel without being encumbered by many books. This technique also had a second advantage: To impress Eastern scholars and savants. The Jesuit missionaries selected to leave already had an exceptional memory and were extremely well prepared. In the case of Matteo Ricci, who was “the director” of the Jesuit missionary enterprise in China, the demonstration of his incredible memory skills also served the purpose of inciting the Chinese to believe in the doctrine unveiled to them.
Herigone-Leibniz: the digit-letter code to extend the capabilities of memory
A few decades after Matteo Ricci, Pierre Hérigone invented the digit-letter code, which would revolutionize the method of memory. This French mathematician had the idea of matching the numbers to the consonants of the alphabet. In order to create memorable sounds, one vowel could be added to each consecutive consonant pair. Shortly after him, Leibniz, a great German thinker, scientist and mathematician, told us: “All attention demands memory.” While he was curator of the Hannover Library, Leibniz had an interested in memory and more particularly in Pierre Hérigone’s code, which he made more flexible. The existence of these codes induces the idea that men had understood that memory is malleable, that it could be trained, stimulated and improved by different processes.
Korsakoff and amnesia
The arrival of the nineteenth century would bring a new eye on memory. At that time, the sciences are making enormous progress. It is in this context that Korsakoff, at the very end of this century, described general amnesia in some of his chronic alcoholic patients. In particular, he described one of his patients in great details: “He was a sick man of thirty-seven, a Russian writer, who had become accustomed to drinking a lot of brandy during his travels to Siberia. […] The patient completely forgot what had happened to him recently; he could not tell if he had eaten that day, if someone had come to see him. What had happened five minutes ago, he could not remember. […] What had happened well before the illness, the patient remembered it perfectly and gave details; but all that had taken place towards the beginning of the disease, the patient remembered it confusedly. For example, he had started a short story in the month of June and had already written more than half of it, and by that time he no longer remembered the outcome he had wanted to give it.” To clarify Korsakoff’s observation, let us take, as Professor Alain Lieury does, the case of a person who drinks coffee while playing chess. If the patient knew how to play chess before the illness pronounced itself, he would then remember the rules and could continue to play because the chess pieces are in front of him. On the other hand, he will not be able to know if he has already put sugar in his coffee, because he will have forgotten to have made this gesture by the time that the sugar melts. I leave it to Alain Lieury to summarize perfectly this phenomenon: “The sick live in their past and in a present that is constantly renewed.” Several decades later, neurosurgery combined with memory tests would demonstrate that amnesia is caused by the temporal destruction of an area called Hippocampus. A discovery owed to the Canadians William Scoville and Brenda Milner. It should also be noted that the destruction of the hippocampus is most often caused by the excessive intake of alcohol and certain drugs such as cocaine.
To evoke involuntary memory, let’s talk of a famous madeleine. The narrator of In Search of Lost Time in Swann’s Way, the first volume of Marcel Proust’s novel, tells us: “The smell and flavor remain for long […]. And as soon as I recognized the taste of the madeleine piece soaked in the herbal tea given to me by my aunt […], immediately, the old gray house on the street, where her room was, came like a stage set to the little pavilion, overlooking the garden, which had been built for my parents on her rear; and with the house, the city, from morning to evening and in all weathers, the Place where I was sent before breakfast, the streets where I went shopping, the paths that were taken if the weather was beautiful. […] All this that takes shape and strength, came out, city and gardens, of my cup of tea.” Proust’s madeleine is thus associated with a trigger that comes to recall a memory in someone’s mind. Although it has been proven today that the memory of odors is much less effective than that of words or images, Proust here refers to a feeling that we all felt one day.
The scientific progress of the twentieth century
It was only in 1904 that the idea of memory leaving a physical trace was advanced, and it was the German biologist Richard Semon who proposed it. He called this trace an engram. With the advancement of technology in the 1940s, the field of neuropsychology emerged and created a biological basis for coding theories. The American biologist Karl Lashley, for example, had devoted much of his research to the analysis of rats in labyrinths, in a systematic attempt to identify the places where engrams are formed in the brain. He concluded in 1950 that the memories are not located in one part of the brain, but are widely distributed throughout the cortex and that, if parts of the brain are damaged, other parts may play the role of the damaged part.
As early as 1949, the Canadian Donald Hebb, had the intuition that the coding of memories occurs when the connections between neurons are established by repeated uses. This theoretical idea would sometimes be called ‘’Hebb’s rule’’. Indeed, the change in the global study of memory in the 50s and 60s was called the “cognitive revolution” and led to several new theories on how to visualize memory. For example, in 1956, the American psychologist George Miller published an article on short-term memory and considered that the latter was limited to what he called “the magic number seven, plus or minus two. So what does that mean? For Miller, the number of objects that can fit in a person’s working memory would be between 5 and 9, depending on the profiles. Twelve years later, in 1968, the Americans Richard Atkinson and Richard Shiffrin described for the first time their model of modal memory, consisting of a sensory register, a short-term memory and a long-term memory.
Nowadays, the study of human memory is considered as part of the disciplines of cognitive psychology and neuroscience, as well as the interdisciplinary link between these two, known as cognitive neuroscience.
Doctor Alzheimer and the discovery of the disease
Before letting Yannick explain the scientific aspect behind the various memories, let’s take the time to discuss Alzheimer’s disease, which is summarized as follows by the French Ministry of Solidarity and Health: “Alzheimer’s disease is a neurodegenerative disease (progressive brain damage leading to neuronal death) characterized by a progressive loss of memory and certain intellectual (cognitive) functions leading to repercussions in the activities of daily life.” It was the German psychiatrist and neuro pathologist Alois Alzheimer who identified the disease in 1907. But by what means was he able to do it? At the time, he was studying the case of Auguste Deter, a 51-year-old patient admitted to the Frankfurt Hospital for dementia. Her symptoms were: memory problems, disorientation and hallucinations. After the death of his patient, Alzheimer performed the autopsy of her brain and described the two brain lesions of the disease. Three years later, in 1910, the name “Alzheimer’s disease” was given to the pathology. It was in the 1980s that the biological constituents of the two lesions characteristic of Alzheimer’s disease were identified. Then, in the 90s, several genes, responsible for the transmission of Alzheimer’s disease in certain families, were identified.
Finally, to end this Podcast about memory, let’s note that forgetting is frequent and that on average, a person forgets 50% of what his/her memory has stored on the last hour, and this figure rises to 80% at the end of the month. But that does not mean that forgetting reflects a definitive suppression of memories. Memories can be forgotten, but can resurge, being triggered, which means that our memory would be provided with clues of recovery to find them.
History of Alzheimer’s Disease
Introduction to the study of human memory
Artificial Intelligence: from the 1270 Ars Magna to the current thinking machines, by J.F. Prévereaud
Criticism – The Long History of Memory, by Katharine Hodgkin
Dossier the Human Memory over History, by Prof. Alain Lieury
History of Memory by Douwe Draaisma
Quintilian, Institution Oratoire
Overview and History of Memory Research
Medico-psychological study on a form of memory diseases – Part 1 – Philosophical Review of France and Abroad, by Serguei Korsakoff in 1899.