Photo: Daniel Leal-Olivas/Corbis

The world has watched in horror as the Islamic State, an ultra-hardline militant Sunni group, has conquered large swaths of Syria and Iraq, effortlessly rolling through Iraq’s United States–trained and –supplied army in the process. IS, which was allied with Al Qaeda before a rupture that can be partially attributed to the former’s flagrant disregard for human rights, has effectively erased the border between Iraq and Syria as part of its stated goal of bringing about a new Islamic Caliphate.

Part of the reason IS (which is still commonly referred to by its old name, ISIS, for Islamic State of Iraq and Syria) has made such shocking progress toward this far-fetched goal is the enthusiasm with which would-be jihadists from all around the world are flocking to the group to fight in Syria and Iraq.

Science of Us spoke with John Horgan, a psychologist at UMass-Lowell who specializes in terrorism and who has interviewed members of a wide variety of terrorist groups, about IS’s appeal, the group’s slick media efforts, and what, if anything, can be done to slow its rising influence and accompanying territorial gains.

So who is the sort of person who joins a group like ISIS?

Looking across groups, whether it’s ISIS, IRA, Al Qaeda, you name it, we know for a fact that there’s no one single pathway to terrorism, even within specific groups, let alone across them. We’ve got lots of evidence that many different kinds of people become involved for many different kinds of reasons, and they end up doing many different kinds of things. Some become snipers, some become bombers, some become beheaders, for example.

The psychological literature has started to turn more and more away from the idea of trying to find a general model of involvement. We can definitely find broad risk factors for understanding how and why someone might become involved, though.

What’s the most common story, then?

People who join these groups are trying to find a path, to answer a call to something, which would basically mean that they’re doing something meaningful with their lives. That is a common denominator across the board. There’s typically a very, very strong moral pull. You often see recruits are driven by this passionate need to right some perceived wrong, to address some sort of injustice, to restore honor to those from whom it’s been taken.

Should we be more scared of ISIS than other, similar groups?

I’ve been studying terrorism for just about 20 years now, and what we’re seeing now is astonishing. ISIS truly is something different. It holds very, very broad appeal to both converts and natural-born Muslims alike. In the eyes of potential recruits, this is fantasy made reality. It’s everything that a would-be jihadist could have hoped for.

The one thing that this movement has done far more effectively than any other terrorist movement is that they’re masters at packaging the fantasy deal. ISIS has a reality distortion field that only Steve Jobs would have dreamt of. In the past, in the other movements I’ve studied, like the IRA, would-be terrorists have had to work very hard, psychologically speaking, to justify to themselves, their families, and others the path that they’re on. ISIS has made that journey of navigating the self-doubt much, much easier. The only real obstacle is actually getting there, geographically, and that certainly doesn’t seem to be slowing people down at all.

I think time will tell if ISIS’s staying power is something we should be worried about. But no terrorist group has ever had the numbers now that we’re seeing from ISIS. If they can effectively make strategies and figure out where they will be one year, two years, five years from now, then we will truly have something very dangerous and different on our hands.

Why is their appeal so much more effective than past appeals? What sets them over the top to make them so successful?

They’ve demonstrated results. They’re capturing cities, they’re flaunting weaponry. They’re creating a safe haven, or refuge, where they can live.

Does that create something of a snowball effect where the more weapons that they have, the more territory they have, the more their appeal grows, which brings in more people?

Absolutely, and it will also likely attract people from other movements. It allows ISIS to say, “Look, we’re the real deal.” For the most part, people have to be involved in terrorist groups for many years before they feel like they’ve achieved anything significant. ISIS is different.

What’s the difference between a fundamentalist and someone who joins ISIS? Are all ISIS members true fundamentalists?

Most radicals don’t act on their beliefs, let alone become involved in terrorism. For the most part ISIS is working very hard on trying to not just provide opportunities for people to go out there, but to say that they’re being honest and upfront about their message. They’re offering an opportunity for people to feel powerful. They’re making disillusioned, disaffected radicals feel like they’re doing something truly meaningful with their lives.

Looking at these selfies and YouTube videos, they offer an opportunity for people to take refuge in a group mentality, but also a chance for people to scowl back at their home countries and say, “Now I have the chance to speak my mind.” Not only that, but, “I can raise my kids in an environment that is free from that sort of corruption.” They’re not just offering a message, but they’re also offering a physical place where this fantasy can be lived out.

It sounds like there’s a population of people who would not have had a lot of convenient options to fight back against what they saw as unfair humiliations 10 or 20 years ago. Now they have a very appealing one.

Exactly. Like I said, the only obstacle is getting out there.

The post-9/11 conversation about terrorism has focused mostly on the concept of dispersed, loosely affiliated cells — a few young men coming together in London, say, planning a bombing, then dispersing. What ISIS is doing is very different, though.

Completely different. And that’s why I think we have to rethink a lot of our assumptions about terrorism — for example, the difference between terrorism and warfare and terrorism and insurgency. This is far more warlike, far more akin to a large-scale insurgent movement than a small-scale terrorism movement.

There’s a very different set of psychological demands associated with someone who’s trying to lay low in a Western city versus someone who’s involved in front-line fighting. This is the stuff that really attracts a far broader set of potential recruits because there isn’t a sense that they have to live a double life, which brings with it a lot of psychological demands.

So in other words, the kind of person who is eager to get an AK-47 and patrol Raqqa or some other part of Syria or Iraq, they might not overlap with the kind of person who would have the wherewithal to plan a bombing in a Western city?

A lot of people want to get involved in those kind of battles. In the past, the reality has been that you end up sitting around in a safe house being bored out of your mind. As a result, a lot of them become disillusioned and they end up trying to justify some pretty low-level, tawdry activity. I think those kinds of psychological difficulties are made far easier when you have a mass movement like this, when you have so many other like-minded individuals out there contributing.

Let’s take a look at a couple of English-language ISIS recruitment videos geared at English-speaking would-be recruits. What makes these so effective?

Al Hayat, ISIS’s media department, are nothing if not effective amateur psychologists. They’re also adept marketers. These are great “Jihadi infomercials” — they’re presenting a limited-time offer, and encouraging potential recruits to act now. The Al Hayat media messages capture the “call of duty” to would-be foreign fighters. In fact, some of these videos rival cut scenes from the actual video-game series “Call of Duty” — they are carefully composed, well-edited videos that capture both the nobility and urgency of joining the fight, juxtaposed with pulse-pounding images and slo-mo video of adventure in battle. The language walks a fine line between trite and noble, but the overall message pulls it off quite well.

The fighters portray themselves as “enlightened.” They have gone from just reading at home to taking action abroad. They try to address every conceivable doubt a would-be foreign fighter might have. In the video featuring the Canadian Andre Poulin, he’s keen to stress that self-doubt is not a reason to stay home. His recruitment message is simple: “There’s a role for everybody.” He and others try to appeal to those back home by saying, Look, if you are honest with yourself you really have no excuses, since the barriers to entry are only those that are self-imposed. Doubt, fears, jobs, money, even children, all the trappings of everyday life — these are all the ingredients of the predictable, mundane existence that would-be recruits are living, and which they can transcend, ISIS argues, by joining the fight.

So are a lot of ISIS’s sheer numbers being driven by people who buy this message, but who don’t have particularly sophisticated ideologies otherwise?

For sure. I’ve always felt that ideology tends to be overstated in many accounts of terrorism. It becomes very important, [and] the more and more time people spend in one of these movements, the more ideological they become. A lot of these YouTube videos that we see are more carefully choreographed than we might be led to believe. There is a uniformity to many of the recruitment videos that are out there.

And once someone joins and that process takes hold, how do individual members go from, say, wanting to fight Bashar al-Assad’s army or the Iraqi army to being willing to commit atrocities against civilians?

We don’t know a lot about it. We certainly know that the engagement in atrocities typically comes from a series of small steps. Look at the socialization of children into ISIS right now. We’re seeing children who are made to engage in group rituals, like marches, displays of strength, and things like that. Then they are made to witness punishment, then they are made to witness torture, then they are made to actually engage in torture. It’s really just a series of small incremental steps. That process of individual dehumanization is the same now as it was 70 years ago when the Nazis brought young children increasingly into their fold.

This stuff doesn’t emerge overnight. Individual recruits will struggle with that. They take refuge in ideology when faced with the reality of doing something horrific. This is where the power of the group becomes very significant.

You could see some of that stuff play out in the segment of Vice’s ISIS documentary about the organization’s indoctrination of children.

These children aren’t willing participants. They’re being groomed, they’re being very carefully staged in front of the camera. You can see that the children are constantly glancing up at the cameraman, or someone off-camera who is saying, “This is the answer you need to give.” This is all very carefully choreographed.

So how do you even start to counteract the influence of a group like this?

I was afraid you were going to ask me that question. I think right now the appeal of ISIS is largely impervious to our messages. I think we’re going to have to find a way to delegitimize their actions, but I’m not optimistic about it.

Osama bin Laden himself said that there is a cost to killing civilians, that it can cause people to turn against a radical movement. Is that helpful here, in a morbid sort of way? It seems that as much as ISIS says nice things about coexisting with local religious minorities when it rolls into a new city, overall the group has a serious self-restraint problem with regard to perpetrating horrible violence against civilians.

Al Qaeda suffered immensely by being quite indiscriminate in what they did. The one marker between an unsuccessful and a successful terrorist group is their ability to change tactics and be much more discriminate in what they do. That time will come for ISIS for sure.

Does your research into why people leave terrorist groups offer any hope?

One of the things ISIS is going to have to be sensitive to internally is not allowing accounts of disillusioned fighters to emerge from their ranks. Disillusionment is very, very common in every single terrorist and extremist group you can think of. That’s something that can be very toxic if those accounts get out and gather momentum.

Disillusionment is the most common reason why people voluntarily choose to walk away from a terrorist group. People become disillusioned if they feel that the group has gone too far, if they don’t seem to have a strategy beyond indiscriminate killing. Disillusionment can arise from disagreements with a leader, it can arise from dissatisfaction with the day-to-day minutiae. There are many directions from which disillusionment can arise, and it’s only a matter of time before those accounts leak out from ISIS, and I think we would do very well to be on the lookout for those kinds of accounts, because they offer an opportunity to dissuade further potential recruits from being involved.

Right now, though, I’m not seeing anything to counter the quite powerful messages that this group is putting out. This is not your grandfather’s terrorist propaganda. This is very, very polished, highly choreographed, and highly persuasive messaging.

(This interview has been edited and condensed.)