The steep and virulent rise of terrorism ranks among the more disturbing trends in the world today. According to the 2015 Global Terrorism Index, terror-related deaths have increased nearly 10-fold since the start of the 21st century, surging from 3,329 in 2000 to 32,685 in 2014. Between 2013 and 2014 alone, they shot up 80 percent. For social psychologists, this escalation prompts a series of urgent questions, just as it does for society as a whole: How can extremist groups treat fellow human beings with such cruelty? Why do their barbaric brands of violence appeal to young people around the globe? Who are their recruits, and what are they thinking when they target innocent lives?

Many people jump to the conclusion that only psychopaths or sadists—individuals entirely different from us—could ever strap on a suicide vest or wield an executioner's sword. But sadly that assumption is flawed. Thanks to classic studies from the 1960s and 1970s, we know that even stable, well-adjusted individuals are capable of inflicting serious harm on human beings with whom they have no grievance whatsoever. Stanley Milgram's oft-cited “obedience to authority” research showed that study volunteers were willing to administer what they believed to be lethal electric shocks to others when asked to do so by a researcher in a lab coat. Fellow psychologist Philip Zimbardo's (in)famous Stanford Prison Experiment revealed that college students assigned to play the part of prison guards would humiliate and abuse other students who were prisoners.

These studies proved that virtually anyone, under the right—or rather the wrong—circumstances, could be led to perpetrate acts of extreme violence. And so it is for terrorists. From a psychological perspective, the majority of adherents to radical groups are not monsters—much as we would like to believe that—no more so than were the everyday Americans participating in Milgram's and Zimbardo's investigations. As anthropologist Scott Atran notes, drawing on his long experience of studying these killers, most are ordinary people. What turns someone into a fanatic, Atran explained in his 2010 book Talking to the Enemy, “is not some inherent personality defect but the person-changing dynamic of the group” to which he or she belongs.

For Milgram and Zimbardo, these group dynamics had to do with conformity—obeying a leader or subscribing to the majority view. During the past half a century, though, our understanding of how people behave both within and among groups has advanced. Recent findings challenge the notion that individuals become zombies in groups or that they can be easily brainwashed by charismatic zealots. These new insights are offering a fresh take on the psychology of would-be terrorists and the experiences that can prime them toward radicalization.

In particular, we are learning that radicalization does not happen in a vacuum but is driven in part by rifts among groups that extremists seek to create, exploit and exacerbate. If you can provoke enough non-Muslims to treat all Muslims with fear and hostility, then those Muslims who previously shunned conflict may begin to feel marginalized and heed the call of the more radical voices among them. Likewise, if you can provoke enough Muslims to treat all Westerners with hostility, then the majority in the West might also start to endorse more confrontational leadership. Although we often think of Islamic extremists and Islamophobes as being diametrically opposed, the two are inextricably intertwined. And this realization means that solutions to the scourge of terror will lie as much with “us” as with “them.”

Following the Leader

Milgram's and Zimbardo's findings showed that almost anyone could become abusive. If you look closely at their results, though, most participants did not. So what distinguished those who did? The pioneering work of social psychologists Henri Tajfel and John Turner in the 1980s, though unrelated, suggested part of the answer. They argued that a group's behavior and the ultimate influence of its leaders depended critically on two interrelated factors: identification and disidentification. Specifically, for someone to follow a group—possibly to the point of violence—he or she must identify with its members and, at the same time, detach from people outside the group, ceasing to see them as his or her concern.

We confirmed these dynamics in our own work that has revisited Zimbardo's and Milgram's paradigms. Across a number of different studies, we have found consistently that, just as Tajfel and Turner proposed, participants are willing to act in oppressive ways only to the extent that they come to identify with the cause they are being asked to advance—and to disidentify with those they are harming. The more worthwhile they believe the cause to be, the more they justify their acts as regrettable but necessary.

This understanding—that social identity and not pressure to conform governs how far someone will go—resonates with findings about what actually motivates terrorists. In his 2004 book Understanding Terror Networks, forensic psychiatrist Marc Sageman, a former CIA case officer, emphasized that terrorists are generally true believers who know exactly what they are doing. “The mujahedin were enthusiastic killers,” he noted, “not robots simply responding to social pressures or group dynamics.” Sageman did not dismiss the importance of compelling leaders—such as Osama bin Laden and ISIS's Abu Bakr al-Baghdadi—but he suggested that they serve more to provide inspiration than to direct operations, issue commands or pull strings.

Indeed, there is little evidence that masterminds orchestrate acts of terror, notwithstanding the language the media often use when reporting these events. Which brings us to a second recent shift in our thinking about group dynamics: we have observed that when people do come under the influence of authorities, malevolent or otherwise, they do not usually display slavish obedience but instead find unique, individual ways to further the group's agenda. After the Stanford Prison Experiment had concluded, for example, one of the most zealous guards asked one of the prisoners whom he had abused what he would have done in his position. The prisoner replied: “I don't believe I would have been as inventive as you. I don't believe I would have applied as much imagination to what I was doing.... I don't think it would have been such a masterpiece.” Individual terrorists, too, tend to be both autonomous and creative, and the lack of a hierarchical command structure is part of what makes terrorism so hard to counter.

How do terror leaders attract such engaged, innovative followers if they are not giving direct orders? Other discoveries from the past few decades (summarized in our 2011 book, co-authored with Michael J. Platow, The New Psychology of Leadership) highlight the role leaders play in building a sense of shared identity and purpose for a group, helping members to frame their experiences. They empower their followers by establishing a common cause and empower themselves by shaping it. Indeed, Milgram's and Zimbardo's experiments are object lessons in how to create a shared identity and then use it to mobilize people toward destructive ends. Just as they convinced the participants in their studies to inflict harm in the name of scientific progress, so successful leaders need to sell the enterprise they envision for their group as honorable and noble.

Both al Qaeda and ISIS deploy this strategy. A large part of their appeal to sympathizers is that they promote terror for the sake of a better society—one that harks back to the peaceful community that surrounded the prophet Mohammed. Last year University of Arizona journalism professor Shahira Fahmy carried out a systematic analysis of ISIS's propaganda and found that only about 5 percent depicts the kind of brutal violence typically seen on Western screens. The great majority features visions of an “idealistic caliphate,” which would unify all Muslims harmoniously. Moreover, a significant element of ISIS's success—one that makes it more threatening than al Qaeda—lies in the very fact that its leaders lay claim to statehood. In the minds of its acolytes at least, it has the means to try to make this utopian caliphate a reality.

Crucially, however, the credibility and influence of leaders—especially those who promote conflict and violence—depend not only on what they say and do but also on their opponents' behavior. Evidence for this fact emerged after a series of experiments by one of us (Haslam) and Ilka Gleibs of the London School of Economics that looked at how people choose leaders. One of the core findings was that people are more likely to support a bellicose leader if their group faces competition with another group that is behaving belligerently. Republican candidate Donald Trump might have been wise to ponder this before he suggested that all Muslim immigrants are potential enemies who should be barred from entering the U.S. Far from weakening the radicals, such statements provide the grit that gives their cause greater traction. Indeed, after Trump made his declaration, an al Qaeda affiliate reaired it as part of its propaganda offensive.

Most Syrian refugees (above) do not view the West as their enemy, a fact that writers in the ISIS-run magazine Dabiq have bemoaned, calling for an end to the “gray zone” of constructive coexistence.

The Gray Zone

Just as ISIS feeds off immoderate politicians in the West, so those immoderate politicians feed off ISIS to draw support for themselves. This exchange is part of what religion scholar Douglas Pratt of the University of Waikato in New Zealand refers to as co-radicalization. And here lies the real power in terrorism: it can be used to provoke other groups to treat one's own group as dangerous—which helps to consolidate followers around those very leaders who preach greater enmity. Terrorism is not so much about spreading fear as it is about seeding retaliation and further conflict. Senior research fellow Shiraz Maher of the International Center for the Study of Radicalization and Political Violence at King's College London has pointed out how ISIS actively seeks to incite Western countries to react in ways that make it harder for Muslims to feel that they belong in those communities.

In February 2015 the ISIS-run magazine Dabiq carried an editorial entitled “The Extinction of the Grayzone.” Its writers bemoaned the fact that many Muslims did not see the West as their enemy and that many refugees fleeing Syria and Afghanistan actually viewed Western countries as lands of opportunity. They called for an end of the “gray zone” of constructive coexistence and the creation of a world starkly divided between Muslim and non-Muslim, in which everyone either stands with ISIS or with the kuffar (nonbelievers). It also explained the attacks on the headquarters of the French magazine Charlie Hebdo in exactly these terms: “The time had come for another event—magnified by the presence of the Caliphate on the global stage—to further bring division to the world.”

In short, terrorism is all about polarization. It is about reconfiguring intergroup relationships so that extreme leadership appears to offer the most sensible way of engaging with an extreme world. From this vantage, terrorism is the very opposite of mindless destruction. It is a conscious—and effective—strategy for drawing followers into the ambit of confrontational leaders. Thus, when it comes to understanding why radical leaders continue to sponsor terrorism, we need to scrutinize both their actions and our reactions. As editor David Rothkopf wrote in Foreign Policy after the Paris massacres last November, “overreaction is precisely the wrong response to terrorism. And it's exactly what terrorists want.... It does the work of the terrorists for the terrorists.”

Currently counterterrorism efforts in many countries give little consideration to how our responses may be upping the ante. These initiatives focus only on individuals and presume that radicalization starts when something happens to undermine someone's sense of self and purpose: discrimination, the loss of a parent, bullying, moving, or anything that leaves the person confused, uncertain or alone. Psychologist Erik Erikson noted that youths—still in the process of forming a secure identity—are particularly vulnerable to this kind of derailment [see “Rescue Mission: Freeing Young Recruits from the Grip of ISIS,” by Dounia Bouzar]. In this state, they become easy prey for radical groups, who claim to offer a supportive community in pursuit of a noble goal.

Anti-Islam rallies, such as this one in Phoenix, Ariz., last spring, abet ISIS's strategy to polarize Muslims and non-Muslims and draw followers into the ambit of confrontational leaders.

We have no doubt that this is an important part of the process by which people are drawn into terrorist groups. Plenty of evidence points to the importance of small group ties, and, according to Atran and Sageman, Muslim terrorists are characteristically centered on clusters of close friends and kin. But these loyalties alone cannot adequately address what Sageman himself refers to as “the problem of specificity.” Many groups provide the bonds of fellowship around a shared cause: sporting groups, cultural groups, environmental groups. Even among religious factions—including Muslim groups—the great majority provide community and meaning without promoting violence. So why, specifically, are some people drawn to the few Muslim groups that do preach violent confrontation?

We argue that these groups are offering much more than consolation and support. They also supply narratives that resonate with their recruits and help them make sense of their experiences. And in that case, we need to seriously examine the ideas militant Muslim groups propagate—including the notion that the West is a long-standing enemy that hates all Muslims. Do our “majority” group reactions somehow lend credence to radicalizing voices in the minority Muslim community? Do police, teachers and other prominent figures make young Muslims in the West feel excluded and rejected—such that they come to see the state less as their protector and more as their adversary? If so, how does this change their behavior?

To begin to find out, one of us (Reicher), working with psychologists Leda Blackwood, now at the University of Bath in England, and Nicholas Hopkins of the University of Dundee in Scotland, conducted a series of individual and group interviews at Scottish airports in 2013. As national borders, airports send out clear signals about belonging and identity. We found that most Scots—Muslim and non-Muslim alike—had a clear sense of “coming home” after their travels abroad. Yet many Muslim Scots had the experience of being treated with suspicion at airport security. Why was I pulled aside? Why was I asked all those questions? Why was my bag searched? In the words of one 28-year-old youth worker: “For me to be singled out felt [like], ‘Where am I now?’ I consider Scotland my home. Why am I being stopped in my own house? Why am I being made to feel as the other in my own house?”

We gave the term “misrecognition” to this experience of having others misperceive or deny a valued identity. It systematically provoked anger and cynicism toward authorities. It led these individuals to distance themselves from outwardly British-looking people. After such an experience, one Muslim Scot said he felt that he would look ridiculous if he then continued to advocate trust in the agencies that had humiliated him. In other words, misrecognition can silence those who, having previously felt aligned with the West, might have been best placed to prevent further polarization. To be clear, misrecognition did not instantly turn otherwise moderate people into terrorists or even extremists. Nevertheless, it began to shift the balance of power away from leaders who say, “Work with the authorities; they are your friends,” toward those who might insist, “The authorities are your enemy.”

A Cautionary Tale

We can take this analysis of misrecognition and its consequences a step further. When we adapted Zimbardo's prison study in our own research, we wanted to reexamine what happens when you mix two groups with unequal power. For one thing, we wanted to test some of the more recent theories about how social identity affects group dynamics. For instance, we reasoned that prisoners would identify with their group only if they had no prospect of leaving it. So we first told the volunteers assigned to be prisoners that they might be promoted to be guards if they showed the right qualities. Then, after a single round of promotions, we told them that there would be no more changes. They were stuck where they were.

We have discussed the effects of these manipulations in many publications, but there is one finding we have not written about before—an observation that is especially relevant to our discussion of extremitization. From the outset of the study, one particular prisoner had very clear ambitions to be a future guard. He saw himself as capable of uniting the guards and getting them to work as a team (something with which they were having problems). Other prisoners teased him; they talked of mutiny, which he ignored. Then, during the promotion process, the guards overlooked this prisoner and promoted someone he viewed as weaker and less effective. His claim to guard identity had been publicly rebuffed in a humiliating way.

Almost immediately his demeanor and behavior changed. Previously he was a model inmate who shunned his fellow prisoners, but now he identified strongly with them. He had discouraged the prisoners from undermining the guards' authority, but now he joined in with great enthusiasm. And although he had supported the old order and helped maintain its existence, he began to emerge as a key instigator of a series of subversive acts that ultimately led to the overthrow and destruction of the guards' regime.

His dramatic conversion came after a series of psychological steps that are occurring regularly in our communities today: aspiration to belong, misrecognition, disengagement and disidentification. Outside of our prison experiment, the story goes something like this: Radical minority leaders use violence and hate to provoke majority authorities to institute a culture of surveillance against minority group members. This culture stokes misrecognition, which drives up disidentification and disengagement from the mainstream. And this distancing can make the arguments of the radicals harder to dismiss. Our point is that radical minority voices are not enough to radicalize someone, nor are the individual's own experiences. What is potent, though, is the mix of the two and their ability to reinforce and amplify each other.

The analysis of terrorism we present here is, of course, provisional as we continue to collect evidence. We do not deny that some individual terrorists may indeed have pathological personalities. But terrorism brings together many people who would not ordinarily be inclined to shoot a gun or plant a bomb. And so there can be no question that understanding it calls for a group-level examination—not just of radicals but of the intergroup dynamic that propels their behavior. This context is something we are all a part of, something that we all help to shape. Do we treat minority groups in our communities with suspicion? Do those who represent us question their claims to citizenship? Do we react to terror with calls for counterterror? The good news is that just as our analysis sees us as part of the problem, it also makes us part of the solution.