Not under-investigated, just suppressed! ;)

The Method of Loci is an ancient technique that used to be taught for thousands of years as a standard part of a classical eduction, way back when people needed to remember things before the invention of smartphones and printing presses. But in the middle ages it was banned for being immoral! Apparently, some bad apples were abusing the Method of Loci to remember "immoral" things they shouldn't be thinking about, using "fabulous" images they shouldn't be imagining.

https://www.guildsomm.com/4cb697f52c/discussion_forums/f/gen...

>Remember to use physical objects in these palaces since they have easily imaginable traits; when you are dealing with more abstract or untranslatable ideas it is best to convert them into objects based on the way the words sound, so Valmur becomes Val Kilmer, Les Preuses becomes purses, etc. Additionally, you don’t need to be concerned with reality when making these memory palaces. The more slapstick, unique and vivid they are, the easier they will stick. Raunchy imagery always works well, to the point where some religious orders in the middle ages banned the practice because it was deemed immoral.

Memory Palace techniques have been known as the Mind Palace, Method of Loci, and Memory Journey, Art of Memory, Ars Memorativa, Memorative Art, Mnemotechnics, Architectural Mnemonic, Graphical Mnemonic, and Textual Mnemonic.

https://en.wikipedia.org/wiki/Method_of_loci

https://books.google.nl/books?id=MRFFAQAAQBAJ&printsec=front...

https://en.wikipedia.org/wiki/Art_of_memory

>The most common account of the creation of the art of memory centers around the story of Simonides of Ceos, a famous Greek poet, who was invited to chant a lyric poem in honor of his host, a nobleman of Thessaly. While praising his host, Simonides also mentioned the twin gods Castor and Pollux. When the recital was complete, the nobleman selfishly told Simonides that he would only pay him half of the agreed upon payment for the panegyric, and that he would have to get the balance of the payment from the two gods he had mentioned. A short time later, Simonides was told that two men were waiting for him outside. He left to meet the visitors but could find no one. Then, while he was outside the banquet hall, it collapsed, crushing everyone within. The bodies were so disfigured that they could not be identified for proper burial. But, Simonides was able to remember where each of the guests had been sitting at the table, and so was able to identify them for burial. This experience suggested to Simonides the principles which were to become central to the later development of the art he reputedly invented.

>He inferred that persons desiring to train this faculty (of memory) must select places and form mental images of the things they wish to remember and store those images in the places, so that the order of the places will preserve the order of the things, and the images of the things will denote the things themselves, and we shall employ the places and the images respectively as a wax writing-tablet and the letters written upon it.

>[...] However, this transition was not without its difficulties, and during this period the belief in the effectiveness of the older methods of memory training (to say nothing of the esteem in which its practitioners were held) steadily became occluded. In 1584, a huge controversy over the method broke out in England when the Puritans attacked the art as impious because it was thought to excite absurd and obscene thoughts; this was a sensational, but ultimately not a fatal skirmish. Erasmus of Rotterdam and other humanists, Protestant and Catholic, had also chastised practitioners of the art of memory for making extravagant claims for its efficacy, although they themselves believed firmly in a well-disposed, orderly memory as an essential tool of productive thought.

>One explanation for the steady decline in the importance of the art of memory from the 16th to the 20th century is offered by the late Ioan P. Culianu, who argued that it was suppressed during the Reformation and Counter-Reformation when Protestants and reactionary Catholics alike worked to eradicate pagan influence and the lush visual imagery of the Renaissance.

>Whatever the causes, in keeping with general developments, the art of memory eventually came to be defined primarily as a part of Dialectics, and was assimilated in the 17th century by Francis Bacon and René Descartes into the curriculum of Logic, where it survives to this day as a necessary foundation for the teaching of Argument. Simplified variants of the art of memory were also taught through the 19th century as useful to public orators, including preachers and after-dinner speakers.

"The Art of Memory" is also the title of a 1966 book by Frances A. Yates about the history of mnemonic systems.

https://en.wikipedia.org/wiki/The_Art_of_Memory

Here's some racy discussion from that book about those problematic morally reprehensible corporeal images:

https://books.google.nl/books?id=MRFFAQAAQBAJ&printsec=front...

>What we are reading is very extraordinary indeed. For scholasticism in its devotion to the rational, the abstract, as the true pursuit of the rational soul, banned metaphor and poetry as belonging to the lower imaginative level. Grammar and Rhetoric which dealt with such matters had to retreat before the role of Dame Dialectic. And those fables about the ancient gods with which poetry concerned itself were high reprehensible morally. To move, to excite the imagination and the emotions with metaphorica seems a suggestion utterly contrary to the scholastic puritanism with its attention severely fixed on the next world, on Hell, Puratory, and Heaven. Yet, though we are to practice the artificial memory as a part of Prudence, its rules for images are letting in the metaphor and the fabulous for their moving power.

>And now the imagines agentes make their appearance, quoted in full from Tullius. Remarkably beautiful or hideous, dressed in crowns and purple garments, deformed or disfigured with blood or mud, smeared with red paint, comic or ridiculous, they stroll mysteriously, like players, out of antiquity into the scholastic treatise on memory as a part of Prudence. The solution emphasizes the reason for the choice of such images is that they 'move strongly' and so adhere to the soul.

>The verdict in the case for and against the artificial memory, which has been conducted in strict accordance with the rules of scholastic analysis, is as follows:

>"We say that the ars memorandi which Tullius teaches is the best and particularly for the things to be remembered pertaining to life and judgment (ad vitam et iudicium), and such memories (i.e. artificial memories) pertain particularly to the moral man and to the speaker (ad ethicum et rhetorem) because since the act of human life (actus humanae vitae) consists in particulars it is necessary that it should be in the soul through corporeal images; it will not stay in memory save in such images. Whence we say that of all the things which belong to Prudence the most necessary of all is memory, because from past things we are directed to present things and future things, and not the other way round."

Lots more on the Memory Techniques Wiki:

https://artofmemory.com/wiki/Main_Page

Here's some more recent research -- isn't the point of memorizing to cause lasting changes to the brain?:

An ancient memorization strategy might cause lasting changes to the brain

Using the memory techniques of the pros alters patterns in brain activity, new research says

https://www.theverge.com/2017/3/16/14950798/memory-palace-me...