I do not visualize with pictures at all. I cannot close my eyes and imagine a loved one's face, what my car looks like, or the route I took to get somewhere. This is the precise opposite of Temple Grandin who speaks of thinking only in pictures. Wikipedia cites Silverman's research, saying 25% of the population thinks only in words. When I studied in college I transcribed sections of my notes that I thought would be important onto colored paper with colored pens; each section of information a different color. I was able to tell you that the information was on the second page at the top in pink ink, not because I could "see" it, but because I had imprinted the information along with the positional and color words. I cannot rotate things in my head. I rotate a map if I want to read it so that I am always going up. What does this have to do with anything?
One of the major strategies we teach for comprehension is visualization. We ask kids to play a movie in their heads, to paint a picture, to see it in their heads. This is a great strategy but we need to recognize that not all students can do this. They all need practice to try, but some will encode the information with a series of verbal descriptions. We need to be sensitive to those who struggle with visualization. They need to try it, but we also have to explain that it might be a radio broadcast rather than a movie. For learners trying to pick up the skill, this might be tough. They do not have the experience with radio that older people do. They are bombarded with visual media. we need to give these students who cannot visualize strategies to help them "see" the images as well.