Are mass shootings contagious?
In a span of less than three weeks, three mass shootings have made international headlines: the terrorist attacks in Paris on November 13th, last Friday's attack at a Planned Parenthood clinic in Colorado and now, the attacks in San Bernardino, California. Wednesday's shooting is the deadliest mass shooting in the U.S. since the Sandy Hook school shooting in 2012.
Sherry Towers says looking at how contagious diseases spread can be helpful in understanding why mass shootings happen with such frequency in the U.S. And she doesn't use the term 'contagion' loosely - she was able to use statistical modelling to successfully predict the peak of the H1N1 virus in 2009.
Sherry Towers is a Canadian professor at Arizona State University, where she teaches statistical modeling.
This interview has been edited for for clarity and length.
What prompted your research into this?
I work with a group at Purdue University in Indiana and in January 2014, I was due to have a meeting with that group on campus. The meeting had to be cancelled because tragically a student walked into a lecture and shot another student dead.
On that day I realized that that was the second or third school shooting I had heard about in the previous approximately week and a half. And I wondered, "Is this some kind of statistical fluke, that these things are clustering together or this some evidence of contagion that might be perhaps spread through the media?" So I talked to some of my colleagues, and we talked about the potential of using a contagion model, fitting it to the data, and looking for evidence of contagion in these types of tragedies.
And what did you find out? How are mass shootings like contagious diseases?
So what we found out was that in shootings that garnered a significant amount of national or international media attention -- where there were lots of people killed -- those were the ones that appeared to show evidence of unusual bunching in time, and that appeared to be contagious. In the U.S., shootings where less than three people are killed happen almost daily. And in that sample, where they only get local media attention, we did not find evidence of bunching. So this led us to hypothesize that contagion, perhaps through media, about these kinds of tragedies is playing a role -- where an individual who's clearly mentally ill or mentally distressed who has access to weaponry is either consciously or subconsciously exposed to the idea to do something similar. Because it really is a contagious process when we are infected with the idea from someone else exposing us to that idea.
And this happens mostly when there are incidents when there were four or more victims, because of the national news coverage?
Yes.
Can you tell me more about the pattern of behavior you saw after a widely reported mass shooting?
You see this unusual bunching in time of these events which suggest contagion is playing a role. But unless the shooter actually leaves some kind of manifesto that says "I was inspired by Columbine," we can't really point to particular shootings and say yes, indeed that person was inspired by a recent event.
When you heard about the San Bernardino shooting, did you think that these could have been triggered by the reporting on the recent mass shootings in Colorado or even in Paris?
There is the potential for that. Certainly the F.B.I. are still investigating that but certainly it does follow rather close on the heels of the Planned Parenthood shooting. And rather close on the heels of the of the Paris shooting.
So you're saying the media is the vector of the information that infects the minds of the people who actually do the shooting. So do you think the media has a responsibility to completely rethink how it covers mass shootings?
The media has the right to free speech to cover what it sees fit. But it is certainly true that media outlets have ceased covering suicides, like in large cities where people would for instance commit suicide by jumping in front of a subway train. The media no longer covers that, they self-regulate themselves. I think that it would be a mistake for the government step in and say, "No, you should not be covering these kinds of events." In the Oregon college shooting, the sherriff refused to say the shooter's name. Ultimately the media found it out anyway and they published it. But the sheriff did try to take a stand and not give any attention to the shooter himself but rather focus on the victims instead. It's an interesting tactic, but I think in order to assess whether or not it's effective everybody has to buy into it. Even though it's been talked about, I do not see any evidence that the media is showing some restraint in covering these shootings.
You're a Canadian living in the United States. Do you despair when you hear about this?
I grew up in Vancouver Island. There was a high prevalence of firearm ownership - I grew up in a household with firearms, and most of the people in my town had the hunted so they had firearms in their home. And yet, there isn't the same problem in Canada with these kinds of events. It doesn't mean it never happens in Canada, but it's much much more rare. And so as a Canadian I know that it is not just firearm ownership, I know that it is not just exposure to violent movies or violent video games or even exposure to the media. There is something clearly very multi-faceted in what underlies the culture of violence in the US.
You study H1N1 and that research is important when it comes to vaccines. Is there an analogy for a vaccine that we could apply to this epidemic?
We found that on average these kinds of events are much more prevalent in states that have a high prevalence of firearm ownership. So if you want to talk about prevention, the one way to prevent these things is to actually try to put sensible gun control laws in place. For instance, require background checks on all firearm purchases.