Book explains why Halloween attractions make us “Scream”

This undated photo shows Margee Kerr, author of the new book "Scream: Chilling Adventures in the Science of Fear." Kerr is a sociologist who studies fear. The book documents her adventures around the world checking out extreme and scary attractions from roller coasters and haunted houses to the CN Tower EdgeWalk in Toronto. (Rachellynn Schoen via AP)