Facebook’s experiment on emotional contagion

Facebook tinkered with users’ feeds for a massive psychology experiment > emotions propagate via social networks

Experimental evidence of massive-scale emotional contagion through social networks

In June 2014, researchers from Facebook and Cornell published in PNAS an experiment run on nearly 700,000 users, whose news feeds were altered to show fewer positive or fewer negative posts. People then wrote slightly more negative or more positive posts themselves: emotions spread through social networks. The study also sparked a controversy over informed consent.

Source: PNAS