How exactly did it come about that one day we were all referring to our rapidly increasing junk email as spam? Why does one particular pet name suddenly become popular… all across the nation? A new study delves into these questions and discovers the structure of our social networks influences whether we spontaneously adopt new social conventions. Large social networks which allow us to freely mix are more likely to arrive at consensus than communities which do not permit as much interaction.

“Large homogenously mixing populations were significantly more likely to spontaneously create social conventions than smaller populations with less connectivity,” wrote the authors in their published paper. In a release, Dr. Damon Centola, an associate professor at University of Pennsylvania, further explained how certain ideas or behaviors gain a foothold and suddenly emerge as popular.

“It is a common misconception that this process depends upon some kind of leader, or centralized media source, to coordinate a population,” Centola said. “We show that it can depend on nothing more than the normal interactions of people in social networks.” Social norms shape every aspect of our lives, from how we say hello to how we eat. To understand how these conventions arise and take hold of groups of people, Centola and his co-author Dr. Andrea Baronchelli, a physicist and assistant professor at City University London, invented an experiment featuring a web-based game. After recruiting participants using online advertisements, the research duo randomly divided them into one of three social network groups.

Three Network Types

Participants in the "geographical network" interacted with just four other players and, when it came time to play, they were randomly partnered with others in the same spatial neighborhood. Participants in the "small world network" similarly interacted with just four others, but they played with random partners selected from diverse neighborhoods. Participants in the "random mixing network” interacted with as many people in their group as they wished and played with random partners selected from their entire network.

The game worked like this: Participants were paired, shown a photograph of a human face, and asked to give it a name. If both players provided the same name, they won a small amount of money. If they failed, they lost a small amount of money (though they did not have to pay off their debt), and saw their partner's name suggestion.

The "Name Game" continued with new partners for as many as 40 rounds. Throughout, the players remained ignorant of each new partner's identify. They also did not learn their position with their network, which consisted of 24 players.

Strangely, distinct patterns soon emerged. In both the geographical and small world networks, participants quickly arrived at partial consensus but never settled on one overall "winning" name for the population. Instead, a few names quickly emerged as popular choices, but the participants never elevated one of those names to overall winner.

Spontaneous Consensus

Something else entirely happened among the participants in the random mixing network. At first, it was utter chaos. Everyone said different names and no one would coordinate, but then all of a sudden people who had never interacted with each other were all using the same names. Ultimately, everyone agreed on a single "winning" name within this network.

“Consensus spontaneously emerged from nothing,” Centola said.

Wanting to be certain of their results, the researchers doubled the size of the networks to 48 players and conducted the experiment again. The same patterns repeated themselves. Once again, the researchers doubled each network to 96 players, and once again they saw a duplication of results. This consistency indicates these patterns likely would scale up indefinitely, suggest the researchers, who also note the process of consensus building can be manipulated by adjusting how participants interact with one another.

“By making simple changes to a social network, the members of a population become more likely to spontaneously agree on a social norm,” Centola said. Considering the results of this study, global norms of behavior, attitudes, and who knows, political structures may be inevitable in the post-Internet age.

Source: Centola D, Baronchelli A. The spontaneous emergence of conventions: An experimental study of cultural evolution. PNAS. 2015.