11/19/2010 10:10 am ET Updated May 25, 2011

The Divorce Contagion: An Interview With Rose McDermott

When Rose McDermott, a professor of political science at Brown University, got divorced two years ago, she noticed that a cluster of her friends were splitting up at around the same time. She sensed this was no coincidence, and her hunch sparked one of the more interesting academic inquiries to have surfaced around the topic of divorce in recent years.

Earlier this year, McDermott and two colleagues -- James H. Fowler of the University of California, San Diego, and Nicholas A. Christakis of Harvard University - published a paper titled Breaking Up is Hard to Do, Unless Everyone Else is Doing it Too. Their study shows that divorce can spread like a virus among friends, siblings and co-workers. I interviewed McDermott via an extended email exchange.

KH: Are you the first to study the influence of social networks on divorce, and what got you interested in looking at this particular aspect of divorce?

RM: Yes, as far as we are aware, we are the first to look at the influence of social networks on divorce and the influence of divorce on social networks.
When I got divorced, I felt like the zero node among my friends. I knew my colleague James Fowler worked on social networks and had a good data set we could use, so he joined me in taking a look at whether my intuition - that divorce spread like a virus -- was right. And it was.

KH: When you say you felt like "the zero node," do you mean you were the first in your cluster of friends to get divorced?

RM: Yes, although it turned out that a friend of a friend had gotten divorced first and another friend instigated proceedings prior to my own, so while I felt like the zero node, I in fact was not. I do not believe I was influenced by them, but that was part of the point of undertaking the investigation. I still don't believe I was, but you never know.

KH: When you say you never know, do you mean that you never know what the dynamic really was between you and friends who were in troubled marriages, and how that dynamic might have had an influence on you that you weren't even aware of at the time?

RM: We often don't understand what influences us, or how, or why.

Divorce is so personal and devastating that it seems like it has be completely under the control of the individuals involved. And yet it appears, given our data, that like a disease, it can be communicated through social networks in ways we don't completely understand, and may not be fully aware of.

But once we know something might influence us, we can pay attention to it. I guess if divorce spreads like a virus, awareness of those associations serves to immunize us and sets up a firewall so that we can be more vigilant about what we need to do to make ourselves less susceptible, like work hard to help our friends whose marriages are in trouble.

Our study says is that if you care about your marriage, the state of your friends' marriages is your business, because their outcome can affect your own. That does not give you license to be invasive, but it does mean that paying attention to how your friends talk and think about their marriage, and how such forces influence the way you think about, and act, in your own marriage, can influence your own risk of divorce.

KH: Yes, you found that attending to the health of one's friends' marriages helps the durability of one's own relationship. That's something we all probably know intuitively to be true, but it's nice to see it backed up by a study. What is it about tending to friends' marriages that helps us keep our own intact?

RM: I can speculate, but it will not be more than that. One finding we have is that popular people are less likely to get divorced. This suggests to me that having other social outlets, people who share different interests and activities with us, strengthens our primary bonds by bringing back topics of conversation and interest which keep novelty alive and also prevent any one person from putting too much pressure on their partner, or needing too much, which can be debilitating.

KH: You say in the paper that one process to which the clustering of divorce within a social network can be attributed is what you call influence, or contagion. Can you explain what happens in that process?

RM: I think it is best to think of it like disease contagion--there is something about contact that facilitates transmission, although not everyone is equally exposed or equally susceptible for various individual reasons.

We can't say what it is about exposure that makes one divorced person more likely to communicate that risk to others, although we can speculate about some of those reasons. I suspect that for some, it is simply a kind of demonstration effect, a form of persuasion: "See, if I can do it, you can do it, too!"

KH: Were you surprised by your findings overall? It seems to be pretty amazing to me that one's network of friends would have such a strong influence on the health, or lack thereof, of a marriage.

RM: No. I had a pretty strong prior that turned out to be true. My colleagues on the paper have a book called Connected, which details the many ways that social networks influence our lives, so this is one of many, many phenomena that are affected by our social network. We think these things are personal decisions under our control but we are social animals and we are deeply affected by our social networks. Our networks can affect us for good or ill and we need to be aware of those influences so that we can work to emphasize the good and limit the bad.

This is the start of a regular column in this spot. I hope you'll share your own
stories, questions -- and, of course, your viewpoint -- via comments or email