Roxane Cohen Silver, PhD, serves as the only psychologist on the 75-member U.S. Department of Homeland Security's Homeland Security Advisory Council. Since her 2003 appointment to the Council's Academe and Policy Research Senior Advisory Committee, Silver has advised Congress and Homeland Security Secretaries Tom Ridge and Michael Chertoff on the psychological effects of terrorism.

In 2006, she expanded her service to include a position on the Secure Borders and Open Doors Advisory Committee. By expressing her viewpoints, and having the research to back up her claims, she helps high-level policy-makers communicate with Americans about terrorist threats, prevent future attacks and prepare to cope with them when they happen.

"I have strong opinions and I express them," says Silver, who is also a psychology professor at the University of California, Irvine. "I just stick to my position even if I am in the minority."

For more than 25 years, Silver has studied psychological and physical reactions to stressful experiences. In fact, it was a trauma that inspired her career: When Silver was 17, her close friend's father discovered he had a brain tumor and died within three months.

"That inspired me to understand how people cope with traumatic events, and right at that time I started to look at psychology as a career path," she says.

Since then, Silver has led dozens of studies on trauma-related issues, work that built to her role as principal investigator of a national longitudinal study of responses to the Sept. 11 attacks.

Within a few days of the event, she began a three-year survey of 2,500 nationally representative Americans. The first report from the study, published in The Journal of the American Medical Association in 2002 (Vol. 288, No. 10), reported that 17 percent of the U.S. population outside of New York City reported symptoms of post-traumatic stress two months after the attacks, and 5.8 percent did so at six months.

In her work with Homeland Security, Silver draws from her 9/11 study data, as well as her research on other psychological aspects of trauma, coping and communication. She's particularly passionate about refining the advisory system, which describes the current threat level on a scale of green, or "low," to red, or "severe."

The Department of Homeland Security used to raise the alert globally, she says, with an enormous cost to state and local governments.

"One thing that is not very helpful is to scare people without giving them ideas of what they can do concretely to respond to the threat," says Silver, who argued that there should be specificity in the alert.

As a result of her recommendations, when the alert was raised to orange last August, it only applied to the aviation sector and travelers were told the rationale behind the decision. They were also given explicit instructions about bringing liquids aboard airplanes.

Though Silver has noticed that she's one of very few women on the Homeland Security committees, it hasn't intimidated her.

"I am quite intense and opinionated," she says, "and I don't think that beingfemale has ever stopped me in any way from expressing my views."

--E. Packard