The findings help explain several social occurrences, from why different regions of the country have distinct words for the same product (soda vs. pop) to how norms regarding civil rights spread throughout the United States.
"Our study explains how certain ideas and behaviors can gain a foothold and, all of a sudden, emerge as big winners," said lead researcher Dr. Damon Centola, associate professor at the University of Pennsylvania.
"It is a common misconception that this process depends upon some kind of leader, or centralized media source, to coordinate a population. We show that it can depend on nothing more than the normal interactions of people in social networks."
Centola partnered with physicist Dr. Andrea Baronchelli, an assistant professor at City University London. To understand how social norms arise, they invented a Web-based game, which recruited players on the internet through online advertisements.
In each round of the "Name Game," participants were given an online partner. The pair was then 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 and saw their partner's name suggestion. The game continued with new partners for as many as 40 rounds.
Next the researchers wanted to see whether changing the way that players interacted with one another would affect the ability of the group to come to consensus. They began with a game of 24 players, each of whom was assigned a particular position within an online "social network." The participants, however, weren't aware of their position, didn't know who they were playing with or even how many other players were in the game.
The researchers tested the social effects of three different types of networks: the "geographical network," in which the players interacted repeatedly with their four closest neighbors in a spatial neighborhood; the "small world network," in which the participants still played with only four other players, but the partners were chosen randomly from around the network; and the "random mixing" version, in which players were not limited to four other partners, but instead played each new round with a new partner selected at random.
Clear patterns began to emerge in people's behavior that distinguished the different networks. In the geographical and small world network games, players easily coordinated with their neighbors, but they were not able to settle on one overall "winning" name for the population.
Instead, a few competing names emerged as popular options: Sarah, Elena, Charlene, and Julie all vying for dominance, for instance, but with no overall agreement.
However, after the first few rounds of the random mixing game, it first appeared that no winner would ever emerge, as players suggested name after name, trying to match their latest partners' choices, with very little hope of success. Yet within just a few rounds, everyone agreed on the same name.
"Consensus spontaneously emerged from nothing," Centola said. "At first it was chaos, everyone was saying different things and no one could coordinate, and then all of a sudden people who had never interacted with each other were all using the same words."
The experimental results closely resembled the researchers' mathematical model of how network structure might influence the process of social coordination. The model predicted that random mixing would allow one name choice to take off and become a big winner, a concept known as "symmetry breaking" in physics.
"We were shocked at how closely human behavior matched our models," Centola said. "But we were also nervous. It worked so perfectly the first time that we were afraid it was a fluke!" Yet the results remained the same whether the game was played with 24, 48, or 96 players.
"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.
Next the researchers want to investigate how a few coordinated individuals, which Centola terms "committed minorities," can flip the global consensus from one norm to another.
"We would like to know how small the committed minority can be, yet still instigate widespread social change," he said. "It's a question that a lot of people would like to know the answer to."
The findings are published in the journal Proceedings of the National Academy of Sciences.
Source: University of Pennsylvania
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