Social media networks are very interesting examples of a digital media environment that creates a very specific type of information architecture. Facebook, LinkedIn, Pinterest, and other social media sites are online communities based on homophily. This characteristic is sometimes called the Matthew Effect from the work of Robert Merton. He cited the New Testament’s gospel of Matthew, “For everyone who has will be given more, and he will have an abundance.” As they say in political speeches dating back to Roman times, ‘the rich get richer.’

An even older version of this effect is, simply put: “Birds of a feather flock together.”

In network science this is known as preferential attachment. When you begin using a social network like Facebook you are connected to other users of that network through your choices, links, likes, and other interactions.

With preferential attachment, the more connections you make, the more connections will will make in the future. The effect of preferential attachment is obvious — the more connections you make, the more connections you will continue to make.

But the connections will not be random. (This is where the birds of a feather idea really kicks in.) Preferential attachment is truly preferential from the users point of view. If you connect with people who play poker or are fans of a particular sports team, or are relatives of yours then your connections will grow in those directions. You will gather a collection of people in your network who are similar to you in numerous ways.

When Facebook suggest you might like to join a group, or LinkedIn suggest you should follow a brand or company it is not accidental or random. They are pouring fuel on the preferential fire.