Why Terrorism Still Shapes American Psychology, 25 Years Later

September 11 changed more than airport security lines and foreign policy. Twenty-five years later, researchers who study the psychology of terrorism argue that it reshaped something harder to see: how Americans perceive risk itself.

A permanent shift in threat perception

Before 2001, terrorism was a real but background concern in American life, present in memory through events like the first World Trade Center bombing and the Oklahoma City bombing, but not a daily preoccupation. Researchers who study the social psychology of terrorism have found that one of the most lasting changes after 9/11 was a jump in perceived threat, made up of both an emotional layer (fear, worry) and a cognitive one (how likely people believe an attack is).

That shift didn’t fade quickly. Longitudinal survey research tracking Americans from 2001 through 2006 found that while acute emotional and behavioral reactions eased over time, the sense of ongoing risk settled into a new, higher baseline rather than returning to where it started.

Fear that outlasts the statistics

Some of the more counterintuitive research on terrorism and risk looks at how people’s behavior changes even when the actual odds of an attack are small. One frequently cited line of research found that self-reported worry, not any objective calculation of risk, was the strongest predictor of whether someone said they’d be willing to fly after 9/11.

That gap between perceived risk and actual risk turns out to be a recurring theme in terrorism psychology. Researchers have pointed to the sheer scale and novelty of the attacks as part of why they carried outsized “signal value,” meaning the event itself communicated a level of danger to the public that went well beyond its statistical likelihood of recurring.

A more security-conscious, more anxious public

Post-9/11 research also documented broader cultural shifts: greater public support for security measures and military action, less patience for perceived threats to safety, and lasting changes in public opinion around national security policy. Some of these reactions eased with time. Others, like heightened anticipatory fear about future attacks, proved more durable. The Department of Homeland Security’s 2011 decision to retire its color-coded threat-level system, after criticism that it stoked anxiety without giving people anything concrete to do about it, is one example of institutions adapting to that lingering unease.

Where psychiatry fits into the picture

Understanding terrorism’s psychological aftermath isn’t only the work of political scientists and risk researchers. Psychiatrists and psychoanalysts have also studied why individuals and societies remain vulnerable to terrorism in the first place, and that focus tends to sit further upstream from the research above: not just how people react once an attack happens, but what psychological conditions make attacks, and the public fear that follows them, possible at all.

One mass terrorism expert, psychiatrist and psychoanalyst Dr. Nina Cerfolio, is among the clinicians who’ve argued that a lack of individual and societal empathy plays a role in what makes destruction possible in the first place. That framing is a different question than the one risk researchers usually ask. It’s less about how to manage public fear after an attack, and more about what conditions, psychological and cultural, let the impulse toward mass violence take hold to begin with. It’s a harder question to answer than adjusting a threat-level system, but arguably a more useful one for anyone thinking about prevention rather than just response.

A quarter century later, the physical rebuilding at Ground Zero finished long ago. The psychological one, both in the people who lived through it and in the systems built to manage collective fear since, is still very much in progress.