What's really interesting here is that if people actually demonstrated a little social reciprocity by saying 'hello' to each other, they'd realize that security

What's really interesting here is that if people actually demonstrated a little social reciprocity by saying 'hello' to each other, they'd realize that security and having a neighborhood feel aren't mutually exclusive. Think about it - as a potential burglar, which is a more attractive target? A neighborhood where everyone silently ignores you or one where people notice you, make eye contact, wave, and say hello? tl;dr: Saying 'hello' is a just as effective defensive strategy as it is being friendly to your fellow neighbor.