Birds of a Feather Flock Together

What factors are most important in forming friendships? What's more important: actual similarity, or perceived similarity? Find out...


Have you ever stopped to think about why you’re friends with the people you’re friends with?

If you have, chances are that you’ve noticed that your friends share some things in common with you. Maybe you all went to the same school or laugh at the same TV shows.

We tend to like and spend time with people that are like us.

This explains why we’re more likely to become friends with people that are of the same gender, age, ethnicity, and level of education as us. Social psychologists call this homophily and it’s one of the most replicated effects in psychology research.

But homophily between friends doesn’t stop at demographic characteristics.

We tend to be friends with people that share our views of the world, like our political beliefs. Friends also tend to have similar personalities, especially when it comes to extraversion and agreeableness. This means that if you’re shy and considerate, chances are that your friends are similarly shy and considerate.

The fact that we’re friends with people that are similar to us is not all that surprising.

After all, pretty much everyone has heard the saying “birds of a feather flock together”. But what is surprising is just how deep this homophily goes. For example, a study in 2018 found that friends showed more similar brain wave responses to movies than acquaintances, suggesting that friends may quite literally be on the same (brain) wavelength. There searchers that conducted this study were even able to predict which people were friends just by comparing their brain waves. Other research has shown that friends are also more genetically similar than strangers.

There are a couple of reasons why we like people that are like us. First, people that are similar to us feed our need for validation. Talking with someone that sees the world in the same way we do affirms that our views are okay and that we’re acceptable as we are.

Being similar to someone also means that we’re more easily able to predict their thoughts and reactions. This predictability makes smooth social interaction more likely—there’s less explaining to be done and less opportunity for misunderstanding. Feeling validated and having a smooth interaction feel good and thus make friendships more likely.

BUT, we may face reality distortion...

One important nuance to homophily is that there’s a difference between perceived similarity—believing that someone has a lot in common with us—and actual similarity—objectively having a lot in common with someone.

These two kinds of similarity are related but are not exactly the same. When it comes to long-term friendships, research shows that thinking you have a lot in common with someone is more important than actually having a lot in common with them.

This distinction between perceived and actual similarity may explain why we’re sometimes friends with people that are quite different than us. For example, your friend may be older, have a different job, and even have a different in personality than you. Despite these apparent differences, you may still feel similar because you both deeply care about social justice. This one similarity may be enough to create a sense of homophily.

Perceived versus actual similarity may also explain why sometimes we don’t click with people that are very similar to us on paper. Someone may be of the same gender, educational background and even be similar in personality to you, but you may still struggle to find things to connect over.  

So, next time you’re with your flock of friends, you’ll likely find that your feathers have a lot more in common than not.

Sonia Krol, PhD - Social Psychologist and Resident Friendship Guru @ Pally

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