Why Neighbors Often Become Friends: The Proximity Effect

What Is the Proximity Effect?

The proximity effect describes the robust finding that the closer people are physically, the more likely they are to form friendships. Proximity works by creating opportunities for social interaction— at work, in the neighborhood, in a club.

Festinger, Schachter, and Back (1950) coined the term functional distance: it is not just physical distance that matters but also the architectural layout — the placement of stairs, corridors, and entrances — that determines how often people run into each other and thus how likely friendships become.

The Festinger Study

The classic evidence: in an MIT dormitory, residents were more likely to be friends the closer their rooms were. Students whose door was next to the stairwell had more friends on other floors than their neighbors did — simply because they ran into residents from other floors more often.

Nahemow and Lawton (1975) replicated the finding in a public housing project with a demographically more diverse sample: 88% of the closest friendships existed within the same building. Friendships between people of different ages or backgrounds existed almost exclusively among direct neighbors.

Functional vs. Physical Distance

The crucial insight: it is not the straight-line distance that counts but the frequency of chance encounters. A neighbor in the same hallway whom you see daily is more likely to become a friend than a resident three floors up — even if the physical distance is similar.

This has practical consequences: architecture can foster or prevent friendships. Shared spaces — kitchens, gardens, communal areas — increase functional proximity and thus the chances of meeting. More on spatial arrangements in our article about seating arrangements and social connections.

Proximity Bridges Differences

A surprising finding from Gitmez and Zarate (2022), based on a field experiment at Peruvian boarding schools: the proximity effect was significantly stronger for dissimilar student pairs than for similar ones.

This means proximity and similarity act as substitutes. Where similarity is lacking, proximity can compensate. This also explains Nahemow and Lawton’s finding: friendships across age and background existed almost exclusively among direct neighbors.

Brief Proximity Is Enough

Back, Schmukle, and Egloff (2008) showed: first-year students who randomly sat next to each other in a single orientation eventwere more likely to become friends later. The seating was purely random — yet real friendships emerged from it.

This underscores the point: you don’t need years of living side by side. Even a single chance encounter can trigger the mere-exposure effect — and with it, the first step toward friendship.

Limitations

Most studies come from a university context. In the age of digital communication, the question arises whether online contact weakens the proximity effect. Dunbar (2025) shows, however: the form of contact does not matter, but the frequency does. Physical proximity remains the simplest way to ensure that frequency.

Frequently Asked Questions

Why do neighbors often become friends?

Because of the proximity effect: physical closeness creates opportunities for repeated contact, which generates familiarity and liking through the mere-exposure effect. Festinger et al. (1950) showed: the closer the rooms in a dormitory, the more frequent the friendships.

How important is physical proximity?

Very. Nahemow and Lawton (1975) found: 88% of the closest friendships existed within the same building. Gitmez and Zarate (2022) showed: students randomly assigned to neighboring seats were 16.6 percentage points more likely to become friends.

Can proximity bridge differences?

Yes. Nahemow and Lawton found that friendships between people of different ages or backgrounds existed almost exclusively among direct neighbors. Gitmez and Zarate confirmed: the proximity effect is actually stronger for dissimilar pairs — proximity and similarity act as substitutes.

Is brief shared time enough?

Yes. Back, Schmukle, and Egloff (2008) showed: first-year students who randomly sat next to each other in a single orientation event were more likely to become friends later. Even short-term physical proximity sets the friendship process in motion.