The different emotions we have, the things we learn are momentum shifts.
The more a certain shift happens, the shift is reported by our appropriate brain systems. The brain system’s paperwork, usually written on very thin tracing paper, piles on to a folder that absorbs that certain shift. After a huge number of those certain shifts, eventually we get a big folder stock full of papers, some of which can get lost, and some of the important papers get used over and over again. It might become harder to retrieve specific papers.
For example, if we’ve undergone a lot of momentum shifts in the form of left turns we’ve made in our cars, we’ll have this huge folder of left turns that we can’t possibly remember every left turn. There might be some left turns we might remember at a specific time or we might just remember that we tend to do a particular left turn a lot, but overall, we’ve left turned so much that we can’t quite remember every left turn we’ve made.
That big folder holding all these little papers is part of what we call a “semantic memory”, the memories for the categories we have for life. The little sheets of paper within those big folders make up our “episodic memories”, specific times and places of certain experiences in our life. The size, weight, shape of the folder determines how much, how quickly we recall or even recognize certain things, and that makes up our “procedural memories.”
In Wikipedia, “semantic memory” is defined as memory of general knowledge, facts about the world, main feature being that it’s “absent of context.”
We’ll remember the general fact of a left turn, but we won’t remember where we learned it was indeed a left turn. Similarly, we’ll remember that an apparatus with a flash, a lens, and records certain images of us is called a camera, a furry, purring mammal with whiskers is a cat, an orange spherical object with black lines on it is a basketball. We’ll remember all that, but we probably won’t remember what grade school we were in (which is how I remember a lot of stuff), let alone specific times and places for when we learned it.
If I could extend the metaphor, I think the reason ‘semantic memory’ is “absent of context”, is mainly because the folders usually get too thick. I think context just gets gradually stripped away (or at least lost) from an object or action that we learn about. You’ ve taken too many left turns in your car. You’ve seen what so many cameras, cats, basketballs, have looked like, and feel like that you probably won’t really remember when you actually learned what many of them were. The folder that has recorded the instances of left turns, cameras, cats, basketballs is really really full.
But if you hear about something only once, like me reading about the industrial strength of a material called buckypaper, then that would be defined as a mere episodic memory. I can’t remember the exact date, but I generally remember reading about that when I was with my first job and I remember that it’s really really strong.
It’s important to note however, that I don’t think the “semantic memory” in most people however starts out as a “folder”, I think it starts out as an episodic memory, a thin little sheet of paper.
If we’ve undergone a lot of episodic memories under a certain file, if we get more papers and place into a certain folder, the file becomes bigger and it becomes thicker, it becomes a category and then part of the vast semantic network we have. The category is just one category amongst an infinitude of categories we have.