Recently I learned that a couple of my friends cannot visualize images in their minds. One friend mentioned that it takes effort for him to visualize something you've told him to think about. He also mentioned that when he reads books, he "sees" facts and logical connections, but no imagery. Another mentioned a similar experience--he "sees" facts, but can't even imagine an elephant in his "mind".
Why is it that some might not be able to "see" images in their minds?
