We are the product that Facebook has been testing

[Commentary] . Perhaps we should grow up and accept that this is how the world works when we use an advertising-funded social network stuffed with details of our lives and those of family and friends.

But if we find it creepy, that is what the experiment proves. With this blunder, Facebook’s data scientists have drawn to attention two things of which most of us may have been vaguely aware, but have not pondered very hard. First, Facebook does not feel the need to ask permission before carrying out its tests. Second, Facebook wields incredible power over the behaviour of users. The emotional contagion paper concludes that “given the massive scale of social networks such as Facebook, small effects can have large aggregated consequences.”