It turns out that it's not just viruses and malware that can be passed on to friends when we're not careful how we use our smartphones and computers. A new study by social scientists at Cornell University shows that our emotional state can also be contagious, especially when it's shared on social media.
The researchers, led by professor Jeff Hancock, manipulated the newsfeeds of 698,003 randomly selected Facebook users, stripping out either positive or negative stories to observe how the remaining updates and alerts would affect the emotional states of users.
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"People who had positive content experimentally reduced on their Facebook news feed, for one week, used more negative words in their status updates," explains Hancock, who is a 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 people's status updates."
The findings show that social networks are actually closer to the real world than some might think. Other studies into the effects of Facebook have suggested that users whose friends post overwhelmingly positive, happy updates and news stories become depressed, withdrawn and even envious.
However, in this study at least, it appears the opposite is true and that just like in everyday life, a person's emotional state can be directly influenced by the moods of the people he or she interacts with.
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However, on Facebook, there is no interaction as such, yet Hancock said people's emotional expressions on Facebook predicted their friends' emotional expressions, even days later. What's more, people who were exposed to fewer emotional posts as part of the experiment started to withdraw, becoming less expressive in subsequent posts over the following days.
"This observation, and the fact that people were more emotionally positive in response to positive emotion updates from their friends, stands in contrast to theories that suggest viewing positive posts by friends on Facebook may somehow affect us negatively," said Hancock. "In fact, this is the result when people are exposed to less positive content, rather than more."
The researchers followed Facebook's strict data use policies, meaning that they never saw the content of individual posts. Instead they counted how many times individual positive and negative words were used in over 3 million posts to arrive at their conclusions.
The full findings of the study, "Experimental Evidence of Massive-Scale Emotional Contagion through Social Networks," will be published in Proceedings of the National Academy of Sciences of the United States of America later in June.