‘…But seriously… Add some girls or I’m going to stand really close to the camera so that I’m all anyone can see. Either way, it’s giving people what they want.’
-Chinny

In being around people often, you’re more likely to find them friendly and attractive. It’s called the propinquity effect. This is assuming that all you’re seeing is the person, not any positive or negative action.  Obviously, this works in the opposite direction if the person is a jerk (more exposure results in a disliking the person that much more… Unless you’re into jerks…).

There have been a number of studies on this stuff. One took place in an apartment complex. After a while, people were asked to name their 3 closest friends. For most people, the majority of their close friends were in the same building, despite how close the other apartment buildings were.

It makes sense, as psychology does for the most part. People are comforted by things they recognize, so it’s not too shocking that a familiar face translates to a friendly face.