Just reading and nor thinking makes me fell like: Where are you from? America?
But giving it a little thought:
As we read certain areas in our brain is active of course.
But as our brain works it goes like this: because all brain parts are connected,
all the modules throw out tons of raw info all the time. So form the reading
module raw info goes to the speech module as well - more at "heavier" words and
less on those who we know better (mail me for the entire theory). And because
people usually know how to read well, the movement cannot be seen. You probably
know for your self that children can't read quietly at young age and read faster