The researchers reduced the amount of either positive or negative stories that appeared in the news feed of 689,003 randomly selected Facebook users, and found that the so-called "emotional contagion" effect worked both ways.
Jeff Hancock, professor of communication at Cornell's College of Agriculture and Life Sciences said that people who had positive content experimentally reduced on their Facebook news feed, for one week, used more negative words in their status updates.
He further explained when news feed negativity was reduced, the opposite pattern occurred and significantly more positive words were used in peoples.
Facebook, with more than 1.3 billion users of every emotive disposition, and its news feed feature in which a constantly tweaked, Facebook controlled ranking algorithm regularly filters posts, stories and activities enjoyed by friends proved an ideal place to start.
The researcher plans to direct future research into how expressions of positive and negative emotions influence levels of engagement in other online activities, such as liking and commenting on posts.
The study is published online in PNAS (Proceedings of the National Academy of Science) Social Science.