The bystander effect is a social phenomenon where individuals are less likely to offer help to a victim when other people are present. This occurs because people tend to look to others for cues on how to react, leading to a diffusion of responsibility. The more bystanders there are, the less personal responsibility each person feels to intervene. This effect was famously studied after the 1964 murder of Kitty Genovese, where numerous witnesses failed to assist her. Research shows that when alone, people are more likely to help, highlighting the importance of individual responsibility in emergency situations.