Psych Central Reviews

Reviews Home » Book Review: How Behavior Spreads

Book Review: How Behavior Spreads

It has become a cliché to say that something has “gone viral,” and hardly a day (or a newscast) goes by that I don’t hear that tired phrase at least once. Beyond popular memes, just what is the science of how behaviors spread? Do behaviors really follow the same patterns as diseases?

Author of How Behavior Spreads: The Science of Complex Contagions, Damon Centola is an associate professor in the Annenberg School for Communications and the School of Engineering and Applied Sciences at the University of Pennsylvania and is the director of the Network Dynamics Group, which uses “mathematical models and online empirical methods to study collective behavior.” Their research focuses on how social and institutional changes create unexpected effects on collective political, social, and health outcomes. You can find information about their various projects here.

Centola’s work is fascinating. He uses the spread of disease to explain the dissemination of behaviors, comparing simple contagions, complex contagions, weak connections, and wide bridges to the spread of behaviors across a social group.

He then explains that there are “one and done” interventions such as a vaccination and there are maintenance interventions, or a behavior that must repeat over time to be effective, like a medication regimen.

While a communicable disease is a simple contagion that can be easily spread — you don’t necessarily have to know anything about or even be acquainted with a person who spreads a cold your way — behaviors are more complicated. The ways we think would work to spread a behavior or diffuse it often fails, and ways we think won’t work succeed.

Centola examines how a behavior spreads through a social network (real-world or online), and how that behavior can be maintained over time. He looks at clustered and random networks and the effects of “information brokers” in organizations on the potential for change. Within an organization, an information expert or broker may actually inhibit the spread of innovative behavior across what are often the silos of organizational structure.

Wide bridges work better and have helped disciplines that in the past would have had no contact, like psychology, philosophy, neuroscience and linguistics, to communicate and develop beyond the confines of each individual field. Centola looked at this in terms of Burt’s theory of structural holes, which describes gaps “between two diverse social clusters that prevent access to nonredundant information.”

Many things affect the spread of behavior — the number of people adopting them, your relationship to the adopters and whether you find them credible, the cost of adopting the behavior, the cost/benefit of maintaining the behavior, etc. Anyone who has watched the television program “Brain Games” may have seen their social conformity experiment. If not, you can see it here. It is a low-cost simple contagion.

Centola does a nice, progressive job of introducing concepts and computer models, the strengths and weaknesses of models (what data can and cannot show), how to test the theories of behavioral spread, how behavior spreads within organizations, and how to design social networks to induce change.

I also learned about the “Red Queen Effect,” named for the character in “Through the Looking Glass.” In evolutionary terms, to stay competitive and adaptive, you have to keep evolving, or running as the Queen did, just to stay in the same place.

Centola then looks at the ethics of his work. There are specific structures and techniques that go beyond traditional epidemiological work and can spread beneficial behaviors, but they can also be used for control. Centola talks about how a “network-based approach to social control follows a clear and disturbing logic”:

Complex contagions pose a threat to the regime; however, simple contagions are useful. The diffusion of state propaganda and the solace of pluralistic ignorance can flow easily through the web of weak-tie contacts. A weak social infrastructure thus encourages compliance with the dominant regime while actively preventing the reinforcement necessary to mobilize dissent.

Those thousands of weak ties on Twitter and Facebook can try to enforce a regime’s agenda by stifling questions with overly simplistic catch phrases and name calling. Like any cultural evolution, it happens at a pace we don’t notice. An overwhelming number of simple contagions (tweets, for instance) can overwhelm the space that was once home to more in-depth thought and reasoning.

The norm slowly becomes that we “evolve into patterns that are easily transmitted through weak-tie networks, which is to say, they will be behaviors that are easy, simple, and familiar” and are not very effective at changing behavior or “transmitting ideas that will improve the common welfare.”

More complex ideas get the “too long, didn’t read” treatment. This behavior is nothing new. American individuals I know have a different last name than their German ancestors had at the beginning of World War I. The use of threats and bullying for control is probably as old as humanity. Our brains seek shortcuts, and slogans and stereotypes fit that bill well.

One website Centola discussed that I found particularly interesting is called Patients Like Me. Hundreds of thousands of people are helping others with similar illnesses cope, and they don’t know each other at all. So, there are many positive aspects to these tools, too.

I recommend How Behavior Spreads: The Science of Complex Contagions on many levels. It is especially timely considering the effects of social media such as Twitter, Facebook, and Instagram on political movements around the world. I think it is important today to have an understanding of how online social networks can change our behavior for better or for worse. Like the Red Queen, we need to run just to stay in place.

How Behavior Spreads: The Science of Complex Contagions

Princeton University Press, June 2018

Hardcover, 312 Pages

Book Review: How Behavior Spreads

Psych Central's Recommendation:
Worth Your Time! +++

Your Recommendation: (if you've read this book)
1 Star2 Stars3 Stars4 Stars5 Stars (No Ratings Yet)

Want to buy the book or learn more?
Check out the book on!
(All links to provide a small affiliate fee to us if you decide to purchase the book.)

Stan Rockwell, PsyD

Stan Rockwell, PsyD, LPC has been working in the mental health field for over 40 years. He has worked as a therapist at a state hospital, a community mental health center and has been in private practice since 2009. He has also worked in disaster mental health, crisis intervention, as a client rights investigator and advocate, training and research, and graduate student supervision. He is a past chair of professional development for the Virginia Counselors Association. He has been a volunteer field tester for the World Health Organization in the development of the ICD 11 since 2013 and has been reviewing books for since 2012. He also teaches a class at the College of William and Mary that combines taijiquan and qigong with science and Chinese philosophy. He uses eastern and western methods in his counseling psychology practice. You can find him online at and

APA Reference
Rockwell, S. (2018). Book Review: How Behavior Spreads. Psych Central. Retrieved on September 28, 2020, from
Scientifically Reviewed
Last updated: 3 Nov 2018
Last reviewed: By a member of our scientific advisory board on 3 Nov 2018
Published on Psych All rights reserved.