Catching a mood on Facebook

Positive and negative emotions spread on social network

SAN DIEGO — Facebook users can spread emotions to their online connections just by posting a written message, or status update, that’s positive or negative, says a psychologist who works for the wildly successful social network.

This finding challenges the idea that emotions get passed from one person to another via vocal cues, such as rising or falling tone, or by a listener unconsciously imitating a talker’s body language, said Adam Kramer on January 27 at the annual meeting of the Society for Personality and Social Psychology. Kramer works at Facebook’s headquarters in Palo Alto, Calif.

“It’s time to rethink how emotional contagion works, since vocal cues and mimicry aren’t needed,” Kramer said. “Facebook users’ emotion leaks into the emotional worlds of their friends.”

Preliminary evidence that the emotional undercurrent of a person’s online messages affect his or her friends supports Kramer’s argument, says psychology graduate student Jamie Guillory of Cornell University in Ithaca, N.Y. Guillory and Cornell psychologist Jeffrey Hancock found that groups of three friends communicating by instant messaging used a greater number of negative words and solved a joint task better after one friend had just watched a film clip showing one child bullied by a bigger kid, versus a neutral film clip.

When one friend saw the bullying clips, Guillory suggested, his or her negative feelings spread via written messages to the others and stimulated more active group discussions about the experimental task: coming up with tips to survive freshman year in college.

Volunteers in that study reported not knowing when their friends had seen the bullying clip. Facebook members may also unknowingly pick up on what their friends feel by reading status updates, Guillory speculated.

Kramer used a computer program to identify words signifying positive and negative emotions in Facebook status updates posted by 1 million English-speaking users over three consecutive days in 2010. He did the same for status updates posted by friends of those Facebook users over the next three consecutive days. Since each user had about 150 Facebook friends, Kramer’s study included about 150 million people. More than 800 million people overall use Facebook, he said.

When a user’s status update included more positive than negative words, updates by that user’s friends posted three days later included an average of 7 percent more positive words and 1 percent fewer negative words compared with their updates just before the user’s post appeared. A corresponding pattern appeared after users posted updates with a surplus of negative words.

“That’s not a huge effect, but it’s a real effect,” Kramer said. Across the entire study group, three days after users posted positive updates, the number of updates containing positive words rose by 1.4 million and the number featuring negative words dropped by 679,000 relative to the day before, he reported.

Kramer found the same results whether users’ updates were sampled at the beginning or the end of the week. So any tendency to feel happier on Friday and sadder on Monday didn’t influence emotional trends in status updates.

There’s no way to know if friends actually viewed users’ updates from three days before, he acknowledged. But the findings point to a subtle form of emotional contagion that ripples across the ocean of Facebook users, he concluded.

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.

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