This article originally appeared in the San Francisco Chronicle on March 26, 2014.
If your friend in New York or your cousin in Texas is in a positive mood, it increases your chance of being happy, too – provided you are friends on Facebook. That’s according to a new study that analyzed more than 1 billion status updates from over 100 million Facebook users and found that, on social media, feelings are contagious. And positive ones spread farther than negative ones.
Researchers from UC San Diego and Yale teamed with Facebook data scientists and used software to analyze the emotional content of status updates. They wanted to determine whether emotions spread through social media the same way past research has shown they spread through in-person interactions.
The scientists chose a random event already known to slightly increase the number of negative Facebook posts – a rainy day. When it rains, negative comments from social media users in the soggy city increase by 1.16 percent, and positive ones decrease by 1.19 percent.
Those posts, scientists found, influenced one or two of a user’s friends in other cities where it wasn’t raining. Each additional negative post resulted in 1.29 more negative posts from the person’s Facebook friends. Positive posts, which were more common on non-rainy days, had an even greater reach. Each yielded 1.75 more positive posts among friends in other cities.
The researchers did not analyze posts from friends in the same city as the original poster because they couldn’t be sure that the weather wasn’t influencing them directly. As a result, they say the study probably underestimates how much emotion spreads on social media and the impact it can have.
The study authors wrote that this social media ripple effect “gives rise to clusters of happy and unhappy individuals,” and as new technology emerges and social media use grows, “we may see greater spikes in global emotion that could generate increased volatility in everything from political systems to financial markets.”