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The Chemistry of the Best Friendships

How people sync up in both obvious and hidden ways.

Key points

  • We meet new friends in three ways: Propinquity, shared life stage, shared interests.
  • We seek novelty in life, but prefer familiarity in our friendships.
  • It's normal that you sometimes "click with a person" right from your first meeting.

There are three basic ways that we encounter potential new friends. The first is propinquity or proximity. When we cross paths regularly, live in the same neighborhood or building, or share a workstation in the office with someone, it makes sense that acquaintanceship may deepen into friendship as a result of the consistent exposure that occurs through the use of shared space. While there is an old saying, familiarity breeds contempt, the opposite is also true, we tend to like someone more or find someone more attractive as we spend increasing amounts of time with them.

Social scientists consider this the “mere-exposure effect” and it was first described decades ago (Zajonc, 1968). We grow conditioned to a person’s presence and come to appreciate and count on them showing up in that space. While more men tend to seek novelty in their sexual relationships than women (Hughes et al., 2021), it appears that we all seem to have a soft spot for things and people who are familiar to us. This may actually play a role in more “impromptu” attractions to others, as well, as we’ll see later.

Shared life stage is the second way that we frequently find new friends. We take satisfaction and pleasure when spending time with people who are experiencing the same challenges, or rewards, that we are experiencing. When we move from high school to college or college to our first job, we tend to seek out the company of others who are experiencing the same transition we are. Whether it’s going from singlehood to coupledom or “never parents” to “new parents,” we gain support and a sense of belonging with similar others.

Lastly, shared interests are a reliable path to friendship making. When we get into a new fitness program or start making our own beer or take up calligraphy, we are going to be bumping into new people who share these interests whether it’s through chatting in the juice bar or trying to decide what to buy at the craft beer making supply shop. We join online interest groups, too, that bring us together with people who share our passions and new online and IRL friendships can grow from these interactions.

How Quickly Do We “Know” We’ve Met a New Friend?

We know that there are three paths that lead to new friendship pools where we are likely to build our social networks, but do we ever know “right from the start” that we’ve met a friend? Is “friendship at first sight” possible? Science suggests it is absolutely possible – and the reasons we may feel “instant affinity” for a friend are similar to the reasons we might feel “instant attraction” in a “love at first sight” moment. While we may all have felt the same excitement of instant connection with someone, the “someone” who generates that feeling of warmth in us is going to tell us a lot about who we are as individuals and what we think, feel, or believe we need in a friend or partner. It’s totally on target to say that you can know a person based on the company they keep because we tend to be like, or want to be like, the people we choose to hang with.

Instant Friendship

Science indicates that folks who share a friendship tend to be “in sync” with one another in ways that are both visible and invisible to the naked eye. Visible reasons that we feel immediately connected with potential friends include similarities in age, identity, career path, and likes and dislikes. We tend to like people who are like us. We also tend to like people who see the world the way we do, we like people who share our sense of humor, for instance. If someone laughs at the same things we do, whether it’s something amusing in a person-to-person situation or how our dogs interact at the dog park or the jokes that a co-worker or teacher is trying to crack, we tend to develop an affinity for that person.

Folks who share our taste in music also fall into the “likely friend” category—we’re sharing an identity, of sorts, with other Swifties or Deadheads or Parrotheads, for example. While friendships can develop between those who have seriously diverse tastes from our own, there is likely a deeper shared “something” that draws us to others early on. Research suggests that we are generally similar to our friends in how we perceive, interpret, and respond to our environments.

The resemblance we can’t see includes how our brains fire in synch with those of our friends. Brain wave patterns between friends and between romantic partners show a surprising similarity (Parkinson et al., 2018). In fact, studies indicate that our brain’s neural responses to various stimuli, such as videos, are very similar to those of our close friends. In fact, neural response similarity can even predict the level of closeness between two friends—whether they were friends or friends of friends or even “friends, once or twice removed,” like distant cousins are described.

While we may run across potential friends through proximity, shared life stage, or shared interests, there remains a bit of mystery as to why we “click” with some potential friends and not with others. It may be that the romanticized idea of “chemistry” that we ascribe to romantic attraction is actually a determinant in who we choose as friends, as well.

Facebook image: Kaspars Grinvalds/Shutterstock


Degges-White, S., & Borzumato-Gainey, C. (2014). Friends forever: How girls and women forge lasting relationships. Lanham, MD: Rowman & Littlefield.

Hughes, S.M., Aung, T., Harrison, M.A. et al. Experimental Evidence for Sex Differences in Sexual Variety Preferences: Support for the Coolidge Effect in Humans. Arch Sex Behav 50, 495–509 (2021).

Parkinson, C., Kleinbaum, A.M. & Wheatley, T. (2018). Similar neural responses predict friendship. Nat Commun 9, 332.

Zajonc, R. B. (1968). Attitudinal effects of mere exposure. Journal of Personality and Social Psychology, 9(2, Pt.2), 1–27.

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