The links seems so obvious to me with the often mentioned "mental health" symptom of shouting at random strangers: in a high density environment, our universal

The links seems so obvious to me with the often mentioned "mental health" symptom of shouting at random strangers: in a high density environment, our universal gut reaction to seeing a stranger in misery is to pretend that we did not notice, that we did not see them. I've never been on the receiving end of this, but I imagine that it can only be a matter of time until a healthy human mind will try anything to break that invisible barrier (even if it only makes things worse).