The Bystander Effect is a social psychological phenomenon where individuals are less likely to offer help to a victim when other people are present. This occurs because people tend to assume that someone else will take action, leading to a diffusion of responsibility. The more bystanders there are, the less likely any one person will intervene. This effect was famously illustrated in the case of Kitty Genovese, who was attacked in 1964 while numerous witnesses failed to assist her. Research shows that factors such as group size and perceived danger influence whether bystanders will help, highlighting the complexities of human behavior in emergencies.