In the aftermath of an attack designed to terrify us, it is hard to be anything but afraid.

But research shows that we vastly overestimate the risk posed to us by terrorism.

Fifty-three per cent of Americans say they worry that they, or a member of their family, will become the victim of a terrorist attack — even though their chances of dying from gun violence or in a car accident are much, much higher.

Our flawed perception of the risk posed by terrorism has real consequences — not just for our own mental states, but for the world in which we live. Our reaction to terrorist attacks affects public policy, election results and military decisions. And ironically, it can make us less safe.

Jessica Stern (Boston University)

Jessica Stern is one of the world's leading terrorism experts. Her books include ISIS: The State of Terror and Terror in the Name of God: Why Religious Militants Kill, and she is a professor at the Pardee School of Global Studies at Boston University.

She argues terrorism causes a kind of "spiritual dread," and that we react much more emotionally to threats that involve "moral evil" than to threats associated with "natural evil," like fires or floods.

Another key factor is how a threat is covered by the media. Viewing graphic images of terrorist attacks over and over again, alters our perception of the risk and increases our fear that we will fall victim to terrorism ourselves.

We need to be aware of how what risk analysts call the "availability" of a danger will influence us ... Those who are charged with protecting ordinary civilians need to be aware of this natural tendency to react much more strongly to available risks than to those that are, perhaps, even far more dangerous, but where there isn't a horrifying image that gets stuck in the brain. - Jessica Stern

Stern began studying terrorism in the 1980s. At the time, she says it was seen as an "eccentric" subject, and few people were paying attention to the growing threat posed by groups like Al-Qaeda. Many of her colleagues were focused on the dangers posed by nuclear weapons.

Today, she says terrorism has become "too central to people's imaginations."

Stern says people in positions of power — policymakers and political leaders — need to pay close attention to the dangers posed by terrorism. But she argues the rest of us should refrain from looking at graphic images of terrorist attacks, because those images are bad for our mental health and alter our ability to accurately assess risk.

Click 'listen' above to hear the interview.