When Festinger and his colleagues studied friendship patterns among married couples in an apartment complex at MIT, they found that people who lived at the foot of the stairs or near mailboxes had more friends on upper floors than did other people who lived on the first floor. This illustrates the power of to influence friendship patterns.

Functional distance

Explanation:

Functional distance is the distance that defines a spacing between people in terms of place of infrastructure that displays likeliness of people contacting and meeting each other.This distance plays an important role in relationship of people through meeting each other as per space.

According to the question, functional space is impacting friendship pattern in the case.As people who live near foot of stairs and mailboxes tend to have more friends because of nearness or less distances of houses but people living first floor have more distance among house so they have comparatively less friends.  

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