Edit, 24-Aug-2018: The veracity of this study has been called into serious question. There’s a really good, in-depth article about the many issues with the study, on Techdirt. Rather than just delete this post, as it already gets a bit of traffic I thought it more helpful to add the (better researched) counter to it front and centre.
The New York Times: Facebook Fueled Anti-Refugee Attacks in Germany, New Research Suggests
Karsten Müller and Carlo Schwarz, researchers at the University of Warwick, scrutinized every anti-refugee attack in Germany, 3,335 in all, over a two-year span. In each, they analyzed the local community by any variable that seemed relevant. Wealth. Demographics. Support for far-right politics. Newspaper sales. Number of refugees. History of hate crime. Number of protests.
One thing stuck out. Towns where Facebook use was higher than average, like Altena, reliably experienced more attacks on refugees. That held true in virtually any sort of community — big city or small town; affluent or struggling; liberal haven or far-right stronghold — suggesting that the link applies universally.