People living closer to the sites of terrorist attacks in the United Kingdom were more likely to vote to remain in the European Union during 2016's Brexit referendum, according to a new study analyzing how terrorism affects people's electoral preferences. 

The study, published April 21 in British Journal of Political Science, found that at the aggregate level, higher exposure to terrorism was associated with increased support for the U.K. to stay with the European Union; at an individual level, U.K. residents recently exposed to terrorism were more likely to perceive the benefits of EU membership. 

Research on the noneconomic costs of terrorism is still in its infancy, according to Vincenzo Bove, the lead author of the paper and professor at the University of Warwick. While the direct costs of terrorism, such as the reduction in national output, are more easily examined, the indirect costs of terrorism are hard to measure. This study shows that terrorism contributes to voting and political behavior in addition to other economic and social factors.

With Georgios Efthyvoulou and Harry Pickard, the co-authors of the paper, Bove said he's "been working on terrorism, and its consequences, for a while."

"We were somehow surprised to see that wider public security concerns were not being adequately investigated," he said. "The U.K. has a long history of battling a variety of deadly terrorist attacks within its borders."

The U.K. continues to battle with terrorist groups within its borders, "from the Irish Republican Army to Jihadi-inspired groups to far-right extremism," Bove said. "Given the lingering nature of the threat, with more attacks likely to happen in the future, we should better understand the extent (and the conditions under which) exposure to terrorism can trigger public responses and how these responses, in turn, affect political behavior."

U.K. citizens voted to leave the EU in 2016's referendum, an outcome that was largely unexpected, Bove said. The margin between leave and remain votes was very slim — 51.89% of voters said they wanted to leave the EU, compared to 48.11% who wanted to remain.  

Since then, a lot of research has studied factors that underpin the U.K.'s decision to leave, including concerns surrounding globalization, migration and the protection of jobs, disproportionately focusing on socioeconomic factors. However, not much research has studied the effects of terrorism on people's voting on and perception of whether to leave or stay with the EU. 

The "remain" camp in the early Brexit campaign argued that the EU gives effective tools to fight common threats and that the U.K. is more secure inside the EU. Prominent policymakers working for the security sector, British intelligence agencies and the British military argued that the U.K. should remain in the EU.

Bove and his co-authors had two competing hypotheses about how terrorist attacks may impact people's likelihood of wanting to remain in the EU. 

On the one hand, terrorism could have the effect of fostering nationalist and patriotic feelings, which could increase anti-foreigner sentiments and support for more restrictive immigration policies. If this is the case, then one might expect stronger support to leave the EU in locations more exposed to terrorist attacks, Bove said. 

But on the other hand, terrorist attacks may expose national security weaknesses, according to Bove, and increase awareness of the possible risks of leaving the EU. 

"Terrorist attacks are powerful emotional events that can simultaneously foster both negative emotions," Bove said, "like fear and prejudice, but also more positive emotions, such as solidarity and sense of belonging. Thus, translating this to political behavior is not always clear-cut."

Bove and his colleagues used data on terrorism from the Global Terrorism Database from January 2013 to June 2016 and the percentage of "remain" votes at the district level from the Electoral Commission, complemented with data at the ward level from previous research. 

The researchers found that proximity to a terrorist attack had a positive and highly statistically significant effect on support for remaining — a 1 km decrease in distance from a terrorist attack increased the remain vote share by .022 percentage points, an effect that was stronger for more "sensational attacks" that grabbed the attention of the media, according to the researchers.

Using survey information that coincides with terrorist attacks, the researchers found that, at the individual level, terrorism increased individuals' views that terrorism was the most important issue facing the country, according to Bove, which means that terrorism seems to "displace" attention from other important concerns, including economic conditions and immigration policies. 

These results show that terrorism is a major source of fear in the U.K., its consequences are far-reaching and it triggers strong emotional public responses and can have significant implications in the context of a "highly divisive and significant referendum," Bove said. 

It's important to study and understand the effects of terrorism since public responses can in turn affect political behavior, and so research in this area is imperative to developing appropriate strategies to mitigate the negative consequences of terrorism, according to Bove. 

"Ultimately, we should ensure that terrorism does not shape our decisions," Bove said, "which is the very goal of terrorist organizations: obtain objectives through the intimidation of a large audience beyond that of the immediate victims."

The study "Did terrorism affect voting in the Brexit referendum?" published April 21 in the British Journal of Political Science, was co-authored by Vincenzo Bove, University of Warwick; and Georgios Efthyvoulou and Harry Pickard, University of Sheffield.