When an emergency situation occurs, observers are more likely to take action if there are few or no other witnesses．This phenomenon is referred to as the bystander effect．
The bystander effect is also called the Genovese effect, which is named after Catherine “Kitty" Genovese, a young woman who was cruelly murdered on March 13, 1964．Early in the morning, 28-year-old Genovese was returning home from work．As she approached her apartment entrance, she was attacked and stabbed （刺） by a man later identified as Winston Moseley．Despite Genovese's repeated cries for help, none of the dozen or so people in the nearby apartment building who heard her cries called police for help．The attack first began at 3:20, but it was not until 3:50 that someone first contacted police．
