President Barack Obama said earlier today it is still unknown whether the Boston Marathon attacks, which killed three and left at least 176 injured, were the act of a group or an individual or of foreign or domestic origins. Afternoon Shift spends the hour reflecting on how the government, from local law enforcement to the White House, and we, as a society, respond to acts of terrorism and how attitudes have changed since 9/11. University of Chicago professor and terrorism expert Robert Pape weighs in, as does Tom Kasza, managing director of Hillard Heinz, a security advisory and investigative firm based in Chicago. Marla Vannucci, a clinical psychologist at the Adler School of Professional Psychology, examines the psychological impact of traumatic events. Photo Credit: Getty Images Bill Pugliano