How to Induce a Social Contagion to Improve the World

Social contagions can be a powerful force for good

We always hear about social contagions that negatively impact society: suicide clusters, mass shootings, eating disorders… But a social contagion can also arise in the context of behaviors that are positive. Given the extraordinary power of social contagions, this could be a valuable tool for improving society—especially given the fact that social contagions can be induced.

In 2024, Yale sociologist Nicholas Christakis co-authored a study that demonstrates how this can be done cheaply and effectively. The study centered around encouraging people in isolated villages in Honduras to receive healthcare interventions. Rather than attempting to educate each villager individually, the study selected specific individuals to be educated and then watched the power of social contagion do the rest.

The twist of the study was in how the individuals were selected. In sociology, there’s a concept known as the “friendship paradox,” which describes how, in general, “an individual’s friends have more friends than that individual.” In other words: If you ask a lot of people to name one friend, the people who are named will, on average, be more popular—and thereby have more social influence—than the people who were initially asked at random.

This is just what Christakis did to quickly spark a social contagion. Joined by Edoardo M. Airoldi of Temple University, Christakis randomly chose people to nominate friends to receive an educational intervention. And it worked incredibly well.

According to Christakis:

We found that targeting people’s friends for an intervention induced significant social contagion, creating cascades of beneficial health practices to people who didn’t receive the intervention.

In terms of the specifics of the study, Christakis summarized:

[F]or the same amount of money and resources, you could implement the intervention to 20% of households in five villages instead of all the households in the single village and get five times the results.

Improving the World Through Social Contagion

It’s easy to imagine how the power of social contagion could improve the world, particularly when paired with the friendship-targeting strategy. As Christakis noted in his study, “Any kind of behavior change you wish to effectuate that involves social contagion can in principle be enhanced by using this technique.”

Think about that for a moment: Any kind of behavior. This goes way beyond healthcare interventions in Honduras. Christakis suggests using this power to also promote agricultural innovation and economic development. But even that is just a start.

If you haven’t already, put on your evil genius/benevolent god hat. Now think of a problem in society: illiteracy, low math scores, low birth rates, obesity, drug abuse, gun violence… With sufficient resources, it’s easy to imagine jumpstarting a social contagion in targeted groups to combat each of these.

What are we doing out here on social media, anyway? Are we not sharing ideas, creating memes, growing a following, making connections with bigger accounts in order to increase our influence in the culture?

Sounds an awful lot like we’re already all trying to start social contagions. With a little more planning, a little more cunning, maybe we could manifest real change in the world.