that is allSocial networks like Facebook can spread moods
BBC, 13 Mar 2014
'Emotional contagion' sweeps Facebook
phys.org, Jun 2014
"People who had positive content experimentally reduced on their Facebook news feed, for one week, used more negative words in their status updates," reports Jeff Hancock, professor of communication at Cornell's College of Agriculture and Life Sciences and co-director of its Social Media Lab. "When news feed negativity was reduced, the opposite pattern occurred: Significantly more positive words were used in peoples' status updates."
I do believe that the article above dated March 2014 is referring to the same research as the June 2014 article. Said research caused a major uproar due the ethically questionable but legally solvent 'experiments' done on a set of Facebook participants. So, what I would like to see next is the data showing what happened between the first release of the study's conclusions (in April) and the next burst of media coverage that took place months later. Why the lag and through what channels did it eventually reach mass media?