After running a creative experiment, Damon Centola from the University of Pennsylvania says that the crucial threshold is more like 25 percent. That’s the likely tipping point at which minority views can overturn majority ones. “A lot of models have been developed, but they’re often people speculating in the dark, and writing equations without any data,” Centola says. “Our results fit better with the ethnographic data. It’s really exciting to me how clearly they resonate with Kanter’s work.”

Centola’s team recruited 194 volunteers, divided them into 10 groups, and made them play an online game in which they had to work together to create new social norms. In every round, the volunteers within each group were randomly paired up and shown a photo of a stranger. Without consulting each other, each person suggested a name that best matched the stranger’s face. At the end of every round, both names were revealed. The players earned 10 cents if they had offered the same name, and they lost 10 cents if they had entered different ones. Even though the players only ever interacted with one person at a time, as the game progressed, they quickly arrived at group-wide conventions, where everyone assigned the same name to each face.

At that point, Centola added groups of “activists” to each group. These rabble-rousers all suggested a different name for each face, in an attempt to overturn the established order. And Centola varied the number of activists from one group to the next.

He found that these newcomers were effective in changing minds only if they made up at least 25 percent of the total population. Anything less than that, and their suggestions never took off. Anything more than that, and their alternatives completely replaced the previous status quo. There was nothing in between.

This result matched the predictions from a mathematical model that Centola’s team created to simulate these kinds of interactions. “You see this clump of failures below 25 percent and this clump of successes above 25 percent,” Centola says. “Mathematically, we predicted that, but seeing it in a real population was phenomenal.”

“What I think is happening at the threshold is that there’s a pretty high probability that a noncommitted actor”—a person who can be swayed in any direction—“will encounter a majority of committed minority actors, and flip to join them,” says Pamela Oliver, a sociologist at the University of Wisconsin at Madison. “There is therefore a good probability that enough non-committed actors will all flip at the same time that the whole system will flip.”

Centola agrees. “People need enough reinforcement on a new social norm before they’ll switch,” he says. “Say you shake hands at every business meeting. If you fist-bump, you might seem weird, or trying to be edgy. But if enough people fist-bump, there’s now a feeling that you’re all on the same page. That feeling of riskiness holds people back, and the tipping point creates a group large enough that you’re more likely to meet people showing the same behavior.”