This week marks 20 years since the September 11, 2001, terrorist attacks on the World Trade Center and the Pentagon.

Nearly 3,000 people died that day.

Millions more watched the planes hit the buildings.

Many saw the attacks on live TV.

And two decades later, those images remained seared in the nation's memory.

Researchers call this kind of shared disaster a collective trauma.

For decades, they've studied how collective trauma affects individuals and communities' mental and even physical health.

Who is most at risk after a collective trauma event?

How long do the effects of such trauma last? And after two

decades, are we still dealing with the trauma of 9-11 today? What did we learn in the aftermath of

9-11 that can inform our response to the COVID-19 pandemic, hurricanes, wildfires, and other

large-scale disasters? Welcome to Speaking of Psychology, the flagship

podcast of the American Psychological Association that examines the links between psychological science

and everyday life. I'm Kim Mills. Our guest today is Dr. Roxanne Cohen Silver, a professor

of psychological science, medicine, and public health at the University of

California, Irvine. She studies how people cope with traumatic life events, including both

personal and collective traumas. She was the principal investigator of a multi-year study of the

national impact of the September 11th terror attacks on the nation's mental and physical health.

She has also studied the short and long-term effects of disasters, such as earthquakes, fires, school shootings, and war. Most recently, she and her colleagues have been studying the COVID-19 pandemic and what she calls the cascading collective traumas of 2020 and 2021.

We'll talk about those today as well.

Thank you for joining us, Dr. Silver.

Thank you so much. It's a pleasure to be here.

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