The researchers looked at two terrorist groups: the Provisional Irish Republican Army from 1970 to 1998, and ISIS of 2015. They constructed mathematical networks of both groups using data from news reports for the IRA and a Russian-language social media site called VKontakte for ISIS supporters living in Chechnya, the Balkans and former Soviet states. The study is published today in the journal Science Advances.
While Twitter and Facebook have shut down pro-ISIS messaging and file-sharing, VKontakte has been less successful, according to Wuchty.
"It turns out women were in central positions," Wuchty said. "While they were not having a lot of connections but a high betweenness centrality."
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Having a high "betweenness centrality" means that women were often the shortest path between groups or members who did not already know each other. Women, on average, play a key role in passing recruitment messages, files online videos of beheadings and audio propaganda and prayers as well as connecting distant parts of the network, the study reported.
"They had a lot of interactions [with group members] but not more than men," Wuchty said. "We were surprised that they [women] were brokering between the different parts of the network."
Wuchty noted that his study did not look at actual ISIS fighters, rather women who were part of pro-ISIS groups. The IRA data came from previous work by researchers at Pennsylvania State University and the University of Albany, and used a database of 1312 men and 70 women involved in various IRA activities, mostly bomb-making. The pro-ISIS network on VKontakte incluced more than 24,000 men and 16,000 women.
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One academic who studies terrorism says the work is creative and new.
"I'm surprised that they were able to pull together data to even address that," said Michael Spagat, head of the department of economics at Royal Holloway University of London. "It's an interesting result too that women play a surprisingly important role."