Being a sighted person, it is certainly taking me longer to learn echolocation than it would for someone who is blind, so you may start to register non-visual images in a much shorter amount of time. First this is due to the amount of time I can dedicate to practice, and additionally, my visual cortex is already very busy with my everyday vision to have room for such things as non-visual images. It's known that an unused visual cortex can be re-commissioned to aid in echolocation, so you may have that to your advantage.
I have indeed experienced them and it is an absolute thrill ride when I get a "moment of clarity". Basically, this involves being aware of the big picture as opposed to thinking so hard about the mechanics of it.
So what does it look like?I would describe the feeling of a non-visual image to be a thought. If you picture a shape or shapes in your mind, that might be akin to a non-visual image. In our mind's eye, we can manifest an infinite amount of thoughts, places, shapes and images. When echolocating we can still receive or create this type of imagery, but it will be based on our sensory input as opposed to our imagination. So in that case, I would imagine that it looks different for everyone.
For me these images are comprised of two things:
1. Edges of objects
Remember, there will be no color or text information supplied by echolocation. Objects are outlined because of the sensation that there is a difference between one point and the next. Generally the closer objects have a sense of being more dense, or thicker. Sometimes that translates to being "darker" for me, but like I said, I'm sure it will translate to something a little bit different for each of us.
Have you had any experiences like this during your training? Let me know about your experience with non-visual images in the comment section.