Does anyone know of (tested?) exercises for developing visual mental imagery from scratch?
Warning: Anecdote, personal experience!
I used to have occasional super-vivid "waking dreams", as well as regular dreams, but it was otherwise almost impossible for me to think in terms of images instead of words. Then I had a friend adopt me as his art student. I never learned to draw, but I learned to take his line drawings and add color, then shading.
The process of learning to shade required me to learn to do more visualization than I used to, since I simply couldn't model the correct lighting without having an internal model advanced enough to contain that nuance. It's still weak visualization, since I can't visualize line structures at all (I strongly suspect properly learning to draw would fix this, specifically focusing on taking a scene in front of me and capturing it), but I can visualize colors and shading just fine.
This suggests to me that practice works just fine, and that learning to draw / color / shade will specifically push you to do exactly this, depending on what sort of visualizations you want.
I also found that if I spent 4+ hours continuously practicing, I'd spend at least a few minutes looking at the world and automatically analyzing it in terms of shadow and light and color, which was very helpful for mapping this skill on to reality. So, the occasional obsessive day once you've got the basic knack might help :)
Previously: Generalizing From One Example
Summary: I do not have visual mental imagery. I want it. How do I get it? What exercises, if any, will help?
In further detail... Here's Francis Galton's Statistics of Mental Imagery paper. I'm not quite at the 3% level of completely unable to form mental images, but I'm close. In particular there are three times I have vivid, sharp mental imagery, and the existence of such times tells me I have the brain hardware to visualize. It's enough to let me know that I want it all the time. Unfortunately I don't know how to get it. And searching online has proven difficult and frustrating... for example this article is first of all about a different meaning of "visualize", it's talking about some kind of self-help motivational thingy, and second of all it starts by saying "How to Visualize: I want you to relax and close your eyes. Picture a hot, sunny day at the beach."
Full Stop. Halt, Catch Fire and Burn.
That's already too far. For those of us who don't visualize, practice definitely does not consist of pulling up mental images, playing with them in new ways, and expanding our imagination. I'm very good at imagination in some ways, but I lack that first ability to pull up a mental image. That's what I want to learn how to have!
Here is a description of what I can do, what I have tried, what I have learned, etc.
I see vivid visual mental imagery in 3 situations: