Choose an emotion instead of just a like, and your friends get a better sense of how you feel about their posts. But doing so also tells Facebook something about you.
And that is one big reason Ben Grosser, an artist and a professor at the University of Illinois, who describes his work as "writing software in order to investigate the social effects of software", made an extension that randomises what you tell Facebook about how you're feeling.
It's called Go Rando, and - I'll be honest - it made Facebook likes a little terrifying for me when I first installed it.
