“FOR DECADES, SOCIOLOGISTS and philosophers have suspected that behaviors can be “contagious.” In the 1930s, the Austrian sociologist Jacob Moreno began to draw sociograms, little maps of who knew whom in friendship or workplace circles, and he discovered that the shape of social connection varied widely from person to person. Some were sociometric “stars,” picked by many others as a friend, while others were “isolates,” virtually friendless. In the 1940s and 1950s, social scientists began to analyze how the shape of a social network could affect people’s behavior; others examined the way information, gossip and opinion flowed through that network. One pioneer was Paul Lazarsfeld, a sociologist at Columbia University, who analyzed how a commercial product became popular; he argued it was a two-step process, in which highly connected people first absorbed the mass-media ads for a product and then mentioned the product to their many friends. (This concept later bloomed in the 1990s and in this decade with the rage for “buzz marketing” — the attempt to identify thought-leaders who would spread the word about a new product virally.) Lazarsfeld also studied how political opinions flowed through friendship circles; he would ask a group of friends to identify the most influential members of their group, then map out how a political view or support for a candidate spread through and around those individuals. […]

Obesity was only the beginning. Over the next year, the sociologist and the political scientist continued to analyze the Framingham data, finding more and more examples of contagious behavior. Smoking, they discovered, also appeared to spread socially — in fact, a friend taking up smoking increased your chance of lighting up by 36 percent, and if you had a three-degrees-removed friend who started smoking, you were 11 percent more likely to do the same. Drinking spread socially, as did happiness and even loneliness. And in each case one’s individual influence stretched out three degrees before it faded out. They termed this the “three degrees of influence” rule about human behavior: We are tied not just to those around us, but to others in a web that stretches farther than we know.” (“Are Your Friends Making You Fat?” by Clive Thomson, September 10, 2009). Surprisingly enough, there isn’t one mention of Everett Rogers nor of Gabriel Tarde in this article.

About Rumors (illustration): “Rumors is a multi-disciplinary, Brooklyn-based design studio founded in 2008 by Holly Gressley, Renda Morton, and Andy Pressman. The studio works closely with clients and collaborators to consider the logic, function, and aesthetic of each project.” (read more).

First discovered this illustration via Stüff Stuff.