The mass shooting in Parkland, Florida, isn’t fading quietly from the headlines like so many acts of gun violence before it. Nearly two weeks after 17 people were killed at Marjory Stoneman Douglas High School, media attention is still focused on the survivors and parents of victims who are demanding action on gun control, and lawmakers are showing signs of responding.

That’s enough to make the reaction to this shooting feel different from the aftermath of other gun-related massacres. But is it a sign that Americans are actually changing the way they think about mass shootings and coalescing around a push for gun control? That may depend on whether this event is able to move people past a series of complicated psychological barriers that can keep Americans from thinking about shootings in the same way they think about about other acts of mass carnage, like terrorism, that can sometimes spark more national unity and political momentum.

Understanding why mass shootings haven’t translated into a broader national movement for gun control in the past can help us evaluate whether the Parkland shooting is likely to spur change. According to psychological research, there are a few key reasons why mass shootings haven’t galvanized a lasting, large-scale crackdown on guns so far.

Repeated acts of violence can numb our emotional responses

The exact number of mass shootings is hard to pin down, but gun violence is disturbingly common in the United States, especially compared with other developed countries. And repeated exposure to acts of violence — even when that exposure comes secondhand through the news — can have a numbing effect, according to Yuval Neria, a professor of psychology at Columbia University.

This effect has been mostly studied with regard to terrorist attacks in countries like Israel that have experienced chronic violence, but there’s no reason to imagine that it wouldn’t extend to mass shootings or other acts of gun violence as well, Neria and other psychologists said, because the two events aren’t psychologically distinct. “There isn’t a difference between mass shootings and acts of terrorism in terms of how they affect the brain — they’re both intentional, man-made acts that inflict horror and fear,” he said.

Habituation to terrorism can actually have something of a useful function — by defusing the sense of vulnerability that acts of terror are designed to cause, habituation can prevent terrorism from being effective — but becoming acclimated to repeated violence also creates the sense that these are uncontrollable events for which there’s no clear solution, according to Dov Waxman, a professor of political science at Northeastern University who has studied terrorism and mass violence in Israel. As a result, he said, the public may not exert much pressure in favor of any particular course of action.

People aren’t good at calculating risk

Survivors of many previous mass shootings have tried to make their case for gun control by arguing that we’re all vulnerable to gun violence and should therefore want to enact regulations that could prevent future shootings. “Consider your own children,” said Nicole Hockley, the mother of a 6-year-old who died in the 2012 Sandy Hook shooting, in a listening session with President Trump a week after the Parkland massacre. “You don’t want to be me — no parent does.” That might seem persuasive, especially to parents. But Paul Slovic, a psychology professor at the University of Oregon who studies risk, said that our perceptions of risk and fear aren’t straightforward or logical — they “reside in us as a gut feeling rather than an analytic calculation.”

Slovic’s research has shown that because feelings and intuition play such a strong role in our evaluations of risk, we’re less likely to instinctively perceive items that are familiar or beneficial as something that’s hazardous and should be banned or regulated. This has particularly strong implications for gun owners. “A lot of people own guns or know someone who owns a gun or see a general benefit to guns,” Slovic said. “Positive feelings about something like guns can dampen the emotional response to an event like a shooting and make it feel less risky.”

Of course, having an intense emotional response to a violent event isn’t always a good thing — some researchers have argued that Americans’ fears of terrorism are overblown and result in misdirected and wasted resources. And that poses a risk for the gun violence debate as well, since it’s possible to argue that fears of mass shootings are exaggerated given that they constitute only a small subset of gun deaths overall.

Americans are divided on who — or what — is to blame for gun violence

Another crucial distinction between terrorist attacks and mass shootings, from a psychological perspective, is that terrorists’ ideologies and goals are relatively clear, while mass shooters’ motives tend to be diverse or opaque. The apparent randomness of mass shootings makes it hard to collectively focus blame or anger, according to Sarah Lowe, a professor of psychology at Montclair State University. This could help explain why repeated exposure to terrorist attacks in Israel is seen as having helped strengthen national unity, while mass shootings in the U.S. seem to sow divisions.

This confusion about the motives of mass shooters may also exacerbate the public’s tendency to seize on divergent explanations for acts of gun violence, making it difficult to come to any kind of consensus on policy. A study published last year found that gun owners were far less likely than people who don’t own guns to say that they blamed mass shootings on the availability of guns. While both groups assigned similar levels of blame to the shooter and pop culture, gun owners assigned more responsibility to parenting as a reason for the shooting, while people who don’t own guns placed more of the onus on the weapons. The study also found that people who had guns in their homes were more likely to believe that shootings would happen again, regardless of whether the government took action.

The authors attributed the findings to a psychological concept called “motivated reasoning,” which is when people’s responses and judgments match up with whatever they’re already motivated to believe. Gun owners’ feeling that their identity is connected to guns — and the general politicization of gun rights — likely amplify this tendency, according to the study’s authors. According to polling from Pew, about half of gun owners say that owning a gun is an important part of who they are. Party and ideology are also strongly linked to perspectives on the importance of gun rights: Regardless of whether they own guns, Republicans are far likelier than Democrats to say that the right to own guns is essential to their own freedom.

Gun control advocates, meanwhile, may believe that particular policies are necessary even in the absence of concrete proof that they work. All of this makes it hard to unite the country on a single course of action, especially one that involves government regulation of guns.

The characteristics of the Parkland shooting — and the response to it — mean that this incident could be positioned to overcome some of these psychological barriers. Slovic speculated that focusing on restrictions that target the AR-15 semi-automatic rifle used in the shooting, rather than guns as a category, might make it easier for gun owners to psychologically distinguish the gun used in the shooting from the weapons they personally possess. That could create some common ground that leads to banning or at least limiting the AR-15’s use.

The numbing effect of repeated exposure to violence is also enabled by a quick drop-off in media coverage, but the Parkland students’ vivid stories — combined with images, text messages and videos from the attack — could imbue the event with continued urgency and make viewers empathize with survivors in a new way. “Hearing directly from people who have experienced the trauma is understandably very powerful,” said Sandro Galea, a professor of public health at Boston University who studies trauma and firearms.

But it will be hard for gun control advocates to change the broader social context — in particular, beliefs about the origins of mass shootings. In an ABC News poll released in the wake of the shooting, Americans were more likely to say that better mental health screening and treatment could have prevented the shooting than to say that stricter gun control laws could have prevented it. A substantial minority also said that allowing teachers to carry guns could have prevented the shooting — a suggestion that has been echoed by the president — signaling that Americans still are far from unified on whether gun control is the right course of action for combating mass shootings.

This could be the biggest challenge for activists trying to galvanize support for gun reform. Even if the activism around this shooting can successfully keep the issue of preventing gun violence in the national conversation, that doesn’t mean the country will unify behind gun control as the solution.