Ah, the proverbial "eidetic" memory for the written word.
The interesting thing about that skill is that those people who have it often do *not* understand the message in the words so for them to be able to read it from their memory is a must. In this case reading from the visual memory is no better or faster than reading it off a page from the book.
Once you understand the meaning of the words and applied the information, the actual source or text has less value than the understanding or application you have from the information. In other words you know that 2+2=4 you no longer need the childhood images of 2 lady bugs next to 2 other lady bugs to know that you have 4. You have already processed that information from your childhood to give you faster split second answers. Why waste time calling upon an eidetic memory when our society requires us to think faster than that.
Considering the eye takes in 10,000,000 bits of information per second and you are only consciously aware of 40 bits your brain needs to do some quick elimination to get to the information you really need in a split second. A lingering picture image is unnecessary. I'll even guess that you've been with someone who seeing their car in the carpark has said something to the effect of... "crikey.. someone scratched the paintwork on my car. That wasn't there before... " If we don't have mental photographs we don't notice the difference.
Just for a laugh...
Now for the ladies wondering why the guys never notice a change in hairdo if they have photogrqaphic memories... it comes back to priority and what's too dangerous to notice or rather in their own safety not to notice. they don't know if you like the hairdo or not, they don't know whether they are supposed to like the hairdo or not. So the mind goes... hair changed, wife same, change subject... "what's for dinner?" 
Yes, babayada, I do appreciate the distinction and yes I can recite word for word a couple of the books from when I was 7 to 10, and I wouldn't call that a photographic memory because the images on the pages are fuzzy, yet the words are clear in my mind as is my memory of my irritation surrounding these books.
Alex
