What is Reading?

If, while walking down a corridor of any large organisation, public or private, you saw a notice on a door saying “Knock and Enter” what would you do? Of course, you know, don’t you? How do you think you originally learned what it meant?

Do you know that people suffering  ‘schizophrenia’ always obey the apparent order; they knock and enter every time they pass. Why? They read it quite correctly. So why did they make a mistake but you didn’t?

Are there different ways of reading?