I also struggle to create mental imagery. In this scenario, I do imagine a scene, but it's not generally composed of imagery. I'm aware that this probably won't make sense to someone who has a primarily visual imagination, but when I'm imagining a scene like this, it's more like a network of facts in my head - I piece together the underlying concepts behind what's being described, rather than a visual representation of them.
For example, if I'm imagining a room full of people, I'll have a mental model of everyone's positions in the room, which I'll then update if the story mentions that someone is stood at the left of the room and I'm imagining them at the right. However, I don't have a picture of the room in my head while I'm doing this, there's no image of where the people are stood - it's just something I 'know'.
If I'm given a description of a person's appearance, I incorporate facts about their appearance in my mental model of them, but I still don't form a mental image representing them. If I was asked to draw someone that was described to me, I could attempt it (despite my poor drawing skills), but I would be converting my mental model into a picture at this stage - I wouldn't be drawing from a picture in my head. When I try to recall a fictional character, my mental model of them is overwhelmingly based on things like personality traits, and my perception of how their mind might work. I can remember details of appearance, but they take the form of 'has ~5cm, dark straight hair', rather than a picture of how said hair might look.
This is exactly how my brain works also. It's very frustrating to not be able to call up an image.
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: