The street etiquette of avoiding eye contact lets us go about our business without the distraction of interaction. Most people wear the New York “street face.” It’s a kind of neutral expression with a touch of “don’t mess with me.” It has a do-not-disturb aura. But the truth is that everyone is looking at everyone else all the time. It’s done on the sly, looking away when caught, often with instinctive pretense (as in, I wasn’t looking at you, but at that very interesting doorknob just behind you).
-Jeff Scher, “The Parade”.
Back in the days when I was preparing to attend NYU, they sent a pamphlet with tips and tricks for living in New York. Aside from the whole, look out for cults aspect of it, there was a whole section on not making direct eye contact, lest other New Yorkers view it as a sign of aggression. ‘Cause they were nothing but a bunch of monkeys, I guess.