Maybe it's some kind of protectiveness of the written words that makes people sit that way at catching up and hiding what they are doing?

There's a scene in The Caucasian Chalk Circle in which one of the characters is teaching another one how to eat like a poor man, and he tells him he should put his arm round the bowl protectively, as if afraid of its being snatched from his grasp. This does have something of that look, as if lefties are constantly engaged in confiding secrets to a teenage diary.