Hi Bosy,
I also fall in the unluckly group who just can't get images. I doubt if the author was wrong about the proportion who can get the images. I think It should be 90% of all population who can't get images. Maybe they can but they don't know. I was very disappointed in myself when I know I'm among 30%. I was so serious about it that I didn't do any imagestreaming. I was absolutely wrong. Fortunately, a cool friend of mine told me not to care about images and just describe whatever. He told me to look the colorful objects around me then close my eyes and describe in using all 5 senses. Suddenly , more imgaes will emerge... This should works for most if not all people.
I also found that listening to Memory Supercharger does help.