When studying, making notes is often something you do instead of memorizing information. While some of the information will stick in your mind, most of it will remain on paper or screen. When you need to use the information, in conversation, for example, if you’re studying a language, or maybe in an exam, you won’t necessarily be able to check your notes. Cramming before exams will fill your short term memory with the information, but most of it will melt away after, during or before the exams.

This is why I don’t take many notes any more when studying languages. Instead, I try to memorize as much as possible. I used to take notes and have many notebooks full of vocabulary and grammar notes, but can only remember of fraction of that information. It’s as if my brain decides that it doesn’t need to remember things once they’ve been written.

If you are unable to read and write, have problems with reading and/or writing, such as dyslexia, or if there is no written form of your language, you have to rely partly or totally on your memory. In such cases your memory is probably better than those of us who use writing as an extension of our memories, because memory tends to improve the more you use it.

Even where writing is available, some choose not to use it. For example, in India a huge corpus of Vedic texts has been memorized and transmitted orally from generation to generation in an unbroken tradition dating from about 500BC to the present day. One of the sacred duties of the Brahmins is to memorize and recite these texts.

Among the ancient Celts, writing was prohibited, or used only to a very limited extent. Instead they relied on memorization, and to make this possible, much of their knowledge was transmitted from one generation to another in the form of songs and poems – rhythm and rhyme are powerful aids to memory. Julius Caesar was impressed with the way the Gauls memorized enormous amounts of information, and commented:

It is said that [the Druids] have to memorize a great number of verse – so many, that some of them spend twenty years at their studies. The Druids believe that their religion forbids them to commit their teachings to writing, although for most other purposes, such as public and private accounts, the Gauls use the Greek alphabet. But I imagine that this rule was originally established for other reasons – because they did not want their doctrine to become public property, and in order to prevent their pupils from relying on the written word and neglecting to train their memories; for it is usually found that when people have the help of texts, they are less diligent in learning by heart, and let their memories rust.

Source: http://www.celticcorner.com/language.html

Visible speech is one name for writing, and also the title of an interesting book about writing by John DeFrancis. Speech is not the only thing that writing makes visible though.

In the Harry Potter stories there is a device known as a ‘pensive’, into which wizards can empty their memories and peruse them at their leisure. Writing acts in a similar way: it enables you to extract thoughts, ideas, memories and opinions from your head and to examine them, and also to share them with others.

Seeing your thoughts in black and white in front of you on paper or on a screen can help you to put them in some sort of order. Sometimes, in fact, you may not be quite sure what you’re thinking until you write it down.