Fighting terrorism has become a global obsession, even where it is far rarer than many neglected causes of death. It's hard to fight a problem whose causes you don't understand, however, and scans of the brains of men particularly susceptible to recruitment to terrorism suggest much of what is being done is making things worse.
Terrorists usually claim they are motivated by religious or political beliefs, but sociologists have argued that what distinguishes those who choose that path is more often a hazy sense of grievance than devotion.
This isn't an easy claim to test, but an international team of psychologists have used fMRI scans to investigate. Their findings, published in Frontiers in Psychology, support the idea that it is the sense of feeling unwelcome by society that underlies an individual's turn to terrorism.
The authors gave 535 young Barcelonan men of Moroccan background a survey on how they felt about using violence to promote Islamic causes. The city was chosen based on evidence that Moroccans there are less integrated than anywhere else in Europe. It suffered a terrorist attack while the study was underway. Of those who scored highest for susceptibility to recruitment to terrorism, 38 agreed to undergo brain scans.
After additional questions the participants played the computer game Cyberball, with half of them excluded by virtual players with Spanish names and appearances. They were then asked further questions while their brains were scanned.
The scans revealed high activity in the brain's left inferior frontal gyrus among those who had expressed their willingness to use violence for their cause. This area is associated with the matters people regard as too important to be traded. Crucially, those who had been excluded in the game expressed greater willingness to use fight and die to achieve their aims, and stronger left frontal gyrus activity.
Moreover, even when questioned on topics they previously regarded as not justifying violence, the group that had been excluded showed brain activity similar to when discussing matters they considered fundamental. That is, brief online exclusion was sufficient to encourage terrorist-like brain activity in response to previously safe topics. Imagine the effects of a lifetime of feeling similarly unwelcome.
If Hamid and co-authors are right, every act to make an ethnic or religious minority feel unwanted in their country increases the chance of future acts of political violence. When terrorism does occur, blaming the entire community from which the terrorist came, and questioning the validity of their presence, is effectively acting as a recruitment agency for the terrorists.