Familiar strangers

From danah boyd’s “G/localization: When Global Information and Local Interaction Collide“:

In the early 1970s, Stanley Milgram was intrigued by what he called “familiar strangers” – people who recognized each other in public life but never interacted. Through experiments, he found that people are most likely to interact with people when removed from the situation in which they are familiarly strangers. In other words, two people who take the same bus every day for years may never interact, but if they were to run into each other in a different environment across town, they would say hello and talk about the bus. If they run into each other in a foreign country, they will immediately be close friends.