When you read to yourself, say for leisure (not reading physics or mathematics for example) or in 'ordinary circumstances', do you hear each word in your head? I think I might just be a retard, but it turns out that I'm skim-reading if and only if I don't 'hear the words in my head'. People weren't always able to do this easily. In fact, there was one priest in the ancient world who was renown for the ability to absorb information from literature without making any sound or even moving his lips. How weird is that.