For instance: Fox News' stories tend to provoke anger more than anything else. People tend to react with overwhelming positivity to sports teams and (go figure) political candidates.
And the most "loved" and "wowed" news stories - the stories that, crucially, are most likely to be shared - tend to have a surprisingly narrow set of subjects in common: nature, animals, celebrity children, inspirational local stories of the fireman-rescues-kitten/heroic-service-dog genre.
Are we shocked that these stories provoke shock and love?
No, of course not. But this reaction data is really important, particularly as we continue thinking through Facebook's reluctant role in the information ecosystem.
As Facebook reiterated in its News Feed announcement Wednesday, the site is laser-focused on surfacing content that's "relevant," a subjective term it objectifies through clicks, comments and shares.
Previously, in the era of the "like" button, this metric was blamed for a preponderance of likeable stories on Facebook, to the detriment of more serious, important news. (Ferguson, Missouri, which took hours to trend on Facebook, is a favored example.)
Now that we have more fine-grained data on how users feel about posts, one imagines we'll be surfaced more stories that provoke clicky, sharey feelings -- stories like "cashier is nice" and "area home improvement store hires man with service dog."
Facebook doesn't currently use reactions data in its News Feed; the little icons weren't even mentioned in Wednesday's big News Feed revamp. But the company has made it clear that it intends to use that data to inform its algorithm in the future - and Woolf's analysis gives us a hint at exactly what sorts of stories may look most attractive to it.
For many users, of course, this all poses no problem. (As the stunning success of sites like Little Things has shown, millions of people use Facebook just to check in with their cousins and "love" photos of rescued cats.) But roughly half of all Internet-users alsouse Facebook for news - and personally, when my feed's all family, friends and returning soldiers, I'm leaving for Snapchat.