How behavior spreads

Who’s Damon Centola

Social scientist Damon Centola is an associate professor at Annenberg School for Communication and the School of Engineering and Applied Sciences at the University of Pennsylvania. In his book, How Behavior Spreads: The Science of Complex Contagions, convincingly demonstrates that people’s networks of acquaintances, rather than close friends, matter most in spreading ideas or technology.


A little bit on How Behavior Spreads: The Science of Complex Contagions

A new, counterintuitive theory for how social networks influence the spread of behavior.

New social movements, technologies, and public-health initiatives often struggle to take off, yet many diseases disperse rapidly without issue. Can the lessons learned from the viral diffusion of diseases be used to improve the spread of beneficial behaviors and innovations?

In How Behavior Spreads, Damon Centola presents over a decade of original research examining how changes in societal behavior–in voting, health, technology, and finance-occur and the ways social networks can be used to influence how they propagate. Centola’s startling findings show that the same conditions accelerating the viral expansion of an epidemic unexpectedly inhibit the spread of behaviors.


While it is commonly believed that “weak ties”-long-distance connections linking acquaintances-lead to the quicker spread of behaviors, in fact, the exact opposite holds true. Centola demonstrates how the most well-known, intuitive ideas about social networks have caused past diffusion efforts to fail, and how such efforts might succeed in the future.

Pioneering the use of Web-based methods to understand how changes in people’s social networks alter their behaviors, Centola illustrates the ways in which these insights can be applied to solve countless problems of organizational change, cultural evolution, and social innovation. His findings offer important lessons for public health workers, entrepreneurs, and activists looking to harness networks for social change.

Practical and informative, How Behavior Spreads is a must-read for anyone interested in how the theory of social networks can transform our world.


The Truth About Behavioral Change

How Behavior Spreads: The Science of Complex Contagions, is a great book on the truth about behavioral change for developing intuitions around the spreading of behaviors and information through social networks and why they spread differently.

Knowing about a new service or technology won’t make people adopt it. Would you bother creating a Facebook account or learning the ins and outs of a new software tool if nobody else within your close circle was using the social platform or computer program?

Basically, a book that summarizes a bunch of Centola’s papers in an accessible way. The book tends to repeat itself sometimes, but most similar genre book tend to do the same. The book is clear and consistent — weak ties are good for contagion but clustered networks with wide bridges work better to achieve and maintain complex behaviors.

Despite common misperceptions, Twitter didn’t become the world’s largest communication platform by going viral. Just learning about the platform’s existence didn’t prompt people to start using it. Rather, Twitter grew incrementally, spreading from one social circle to the next. Twitter’s growth pattern was one of “complex contagion” rather than simple, or viral, contagion.


“Twitter didn’t spread virally across the internet; it spread locally, like a grassroots social movement.”

The distinction is relevant for organizations that want employees to embrace new behavior patterns or customers to adopt a new product. Information, like a virus, spreads through simple contagion: You hear it once, and you know it. People who hear you repeat it will know it as well. But adopting technological innovations or behavioral changes requires taking a chance.

So people will embrace innovation only if they see value in it, which is often socially generated. Using Twitter only makes sense if people you know are using it, too. Similarly, you’ll be more likely to consider a new tool useful if you see more and more people around you use it. This kind of “social confirmation” comes from having exposure to new behavior or technology multiple times and through multiple people.

“If we know many people who can vouch for the new technology or business partner we’re considering, we’ll feel much better about diving in.”

Simple contagion relies on weak social ties – long-distance connections among acquaintances. To gain traction, new ideas must reach as many different kinds of people in as many different social circles as possible. Complex contagion, in contrast, depends on strong ties. People adopt an innovation only after they have been exposed to it multiple times and introduced to it by multiple people they trust.


The same principle applies for innovation to spread from one social circle or organizational unit to the next. Within an organization, appointing a single “broker” to spread innovation or promote behavioral changes from one unit to the next won’t suffice. Rather, organizations must build “wide bridges” by establishing several points of contact among the number of people in each unit.

First, people are more likely to trust a new idea if they hear it from multiple people. Second, seeing many different people on an innovating team use new technology in a variety of settings will more likely convince team members of an innovation’s benefits. Third, wide bridges aren’t dependent on individual employees and thus outlast personnel changes.



  • Rather than spreading across the world like an infectious disease, Twitter grew incrementally, from one social circle to the next, following a pattern known as “complex contagion.” 
  • Before embracing something new, people look for “social confirmation” – which happens if they come across the new behavior or technology multiple times and through several people.
  • Twitter’s growth pattern can teach organizations how to get employees to embrace new behaviors or customers to adopt new technology. 
  • To promote adoption across different units, organizations must build “wide bridges” by establishing several points of contact among people in different units.
  • Wide bridges – relationships and interactions with different points of contact in the innovating team – help establish trust in the benefits of innovation.  

Further reading


Author: Muhamad Aarif

A notorious book addict by night and an oil and gas executive by day. As Mark Twain said, "The man who doesn't read good books has no advantage over the man who can't read them." So, read, read, and read some more.

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