Propinquity effect

The propinquity effect is the tendency for people to form friendships or romantic relationships with those whom they encounter often. In other words, relationships tend to be formed between those who have a high propinquity. It was discovered by psychologists Leon Festinger, Stanley Schachter and Kurt Back in what came to be called as the Westgate studies conducted at the MIT (1950).

Propinquity can be more than just physical distance. For example, residents of an apartment building living near a stairway tend to have more friends from other floors than others.

The propinquity effect is usually explained by the mere exposure effect, which holds that the more exposure a stimulus gets, the more likeable it becomes.