Baku, March 13 (AZERTAC). Several studies have so far pointed out the positive and negative effects social networking has on people. While Facebook has offered millions of people a way to connect and interact in a way that may have not been otherwise possible, the social giant has also been a home for cyberbullying.

In a new study, researchers from University of California, San Diego have found that feelings displayed on Facebook are contagious. Publishing a paper in the journal PLOS ONE, the team analyzed over a billion anonymized status updates from more than 100 million Facebook subscribers across the United States and found that positive posts beget positive posts and negative posts beget negative posts. They said that while both are common on the site, the positive posts are more influential.

“Our study suggests that people are not just choosing other people like themselves to associate with but actually causing their friends’ emotional expressions to change,” James Fowler, professor of political science in the Division of Social Sciences and of medical genetics in the School of Medicine at UC San Diego, who is lead author of the study, said in a statement. “We have enough power in this data set to show that emotional expressions spread online and also that positive expressions spread more than negative.”

An abundance of scientific literature exists on how feelings among people can become contagious through direct contact with family, friends and even strangers. Because little is known about the emotional contagion in online social networking, Fowler maintains that his study, and others that may follow, is a good stepping stone in determining what can be transmitted via social media.

Working with Lorenzo Coviello, a PhD student in the electrical and computer engineering department at UCSD’s Jacobs School of Engineering, along with several other researchers from UCSD, Facebook and Yale University, Fowler analyzed anonymized status updates from the top 100 most populous US cities over a period of 1,180 days, between January 2009 and March 2012. The team did not view any usernames or words that were posted. Instead, Fowler and his team relied on automated text analysis using a software program known as Linguistic Inquiry Word Count, which measures the emotional content of each post.

Then, to determine the causal relationship between posts, the team ran an experiment using a natural element: rain. They found that rainy weather changes the tenor of posts in reliable fashion. Rainy days increased the number of negative posts by 1.16 percent and depressed the number of positive posts by 1.19 percent.

Despite the small percentages, the team noted that it wasn’t large numbers they were looking for, but rather showing that a random variable - such as rain - can be used as an instrument in measuring the effect of a change in a user’s posts on another user’s posts. To ensure the rain was not affecting the friends of friends, the team restricted their analysis to friends who lived in different cities where it was not raining. And to ensure that it was not a topic contagion, they removed all weather-related status updates from their analyses.

So, the team implies, the change in emotional expression by those experiencing rainy weather did have an effect on their friends who were in dry cities. They found that each additional negative post yielded 1.29 more negative posts among a user’s friends, while each additional positive post yielded an additional 1.75 positive posts among friends.