People often share stories, news, and information with the people around them. We forward online articles to our friends, share stories with our co-workers at the water cooler, and pass along rumors to our neighbors. Such social transmission has been going on for thousands of years, and the advent of social technologies like texting, Facebook, and other social media sites has only made it faster and easier to share content with others. But why is certain content shared more than others and what drives people to share?

Well, according to Jonah Berger, the author of a new study published in Psychological Science, the sharing of stories or information may be driven in part by arousal. When people are physiologically aroused, whether due to emotional stimuli or otherwise, the autonomic nervous is activated, which then boosts social transmission. Simply put, evoking certain emotions can help increase the chance a message is shared.

In the study, Berger, the Joseph G. Campbell Jr. Assistant Professor of Marketing at the University of Pennsylvania, suggests that feeling fearful, angry, or amused drives people to share news and information. These types of emotions are characterized by high arousal and action, as opposed to emotions like sadness or contentment, which are characterized by low arousal or inaction. He is also interested in how social transmission leads online content to become viral.