> Writing in the New Republic in 2014, Jonathan Zittrain, professor of international law at Harvard University, pointed out that, given the massive amount of information it has collected about its users, Facebook could easily send such messages only to people who support one particular party or candidate, and that doing so could easily flip a close election – with no one knowing that this has occurred. And because advertisements, like search rankings, are ephemeral, manipulating an election in this way would leave no paper trail.

> ...another Facebook experiment, published in 2014 in PNAS, prompted protests around the world. In this study, for a period of a week, 689,000 Facebook users were sent news feeds that contained either an excess of positive terms, an excess of negative terms, or neither. Those in the first group subsequently used slightly more positive terms in their communications, while those in the second group used slightly more negative terms in their communications. This was said to show that people’s ‘emotional states’ could be deliberately manipulated on a massive scale by a social media company, an idea that many people found disturbing. People were also upset that a large-scale experiment on emotion had been conducted without the explicit consent of any of the participants.