Facebook has been quietly adding a “Likes in Common” link to personal profiles in recent weeks. Located in the Likes box beneath Friends and above Photos in the left sidebar, it pops up a window showing which Pages both you and another user are connected to.
Visibility of the Likes panel can be controlled in the Privacy Settings->Basic Directory Information, meaning you are able to see your Likes in Common with non-friends if they allow it. The feature is important to Facebook because it gets users to interact with the Likes panel, increasing the probability that they’ll form new connections with Pages
The Likes panel link states “[#] Likes in Common”, but graphically only shows one or zero of these mutual Likes. This prompts the user to click the link to learn of the others, increasing engagement with the panel. By placing a mutual Like in the far left slot, Facebook creates a trusted recommendation for the as-yet-unliked Pages in the right two slots. Since you already share one Like, you’re inclined to think their other Likes might be of interest as well.
When two people have mutual Likes, there is about a 65% chance that one will be shown graphically in the far left spot. More than one mutual Like is only shown graphically if a user has no other non-mutual Likes.
What’s interesting is the order in which Pages are shown in the All Likes and Mutual Likes tabs of the pop up. While there isn’t an exact hierarchy of how Page categories are ordered, they appear to be grouped into five types which divide the list into regions. At the top are civic categories for Park, Museum/Attraction, and Library/Public Building. Next are brands, products, and services such as categories for Technology Product/Service, Consumer Products, Food/Beverage, Health/Beauty, Professional Service, and Sports/Athletics. In the third region are smaller business categories such as Local Business, Online Store, Store, Restaurant, and Bar. Near the bottom are organization categories including Education, Religious Organization, Politician and Non-profit. At the end of the order are the media categories for TV Show, Movie, Game, Musician, Website, Page, and Application.
These may be ranked to surface Pages from categories like Product/Service which weren’t supported before the interests-to-Likes profile conversion, while demoting categories like Musician of which many users converted multiple interests into Likes. Alternatively, the ranking could simply favor Facebook itself, as the site’s various product and official Pages fall into the preferred second type/region.
Likes in Common offers users interesting data about their similarities with other users while encouraging them to find new Page to connect to. Along with helping to grow Pages, the feature may inspire third-party developers to create a more sophisticated way of determining with whom you have the most overlapping or differing interests.