The psychology behind our fear of terrorism

President Obama and law enforcement have been telling us not to let fear of terror control our lives. CBS News' Dr. Jon LaPook talked to an expert on the impact of fear on our health, clinical psychologist Dr. Justin Sinclair.

Dr. Sinclair: One of the things I think is different about this threat is that it's on-going, people can't know when or where or how it's going to happen. It's this thing that never ends. And it's ubiquitous. It's everywhere.

Dr. LaPook: How does that affect their lives?

Dr. Sinclair: They tend to avoid different aspects of their lives. They fly less, they ride on public transportation less. They go into public settings less. There's been research that's shown they have a tendency to engage people from different cultural backgrounds less. They even consume media less, ironically.

Dr. LaPook: What have you learned over the last 10 years of studying this that might surprise people?

Dr. Sinclair: How potent fear can be in terms of altering people's lives. And the impact that it can have in different aspects of life, whether it's making decisions about a president, whether it's supporting different policies that are important socially, or even down to how people live their everyday lives.

Dr. LaPook: Is there a danger to society of people incrementally changing their behavior over time because of terrorism?

Dr. Sinclair: Yeah, I think it sort of changes the structure of our country. It changes the structure of our government. I think fear can maybe even change things in ways that weren't consistent with how the country was founded originally.

Dr. LaPook: As a psychologist, is there some insight into that?

Dr. Sinclair: I think fear moves people to become much more polarized in their viewpoints and I think that fear motivates people to go to further lengths to feel safe.

In small doses, fear can be a lifesaver, prompting us to react to danger. But in large doses, it can cause fatigue, depression -- even a heart attack or stroke. Dr. Sinclair says it's important to continue with a normal routine if possible.

If fear starts taking over and you find yourself anxious and avoiding things, he says it may be time to get professional help.