The bystander effect, or bystander apathy, is a social psychological phenomenon that refers to cases in which individuals do not offer any means of help to a victim when other people are present. The probability of help is inversely related to the number of bystanders. In other words, the greater the number of bystanders, the less likely it is that any one of them will help. Several variables help to explain why the bystander effect occurs. These variables include: ambiguity, cohesiveness and diffusion of responsibility.
In the video below, a live situation was tested at the Liverpool Street Station in London with 3 different actors, a homeless guy, a woman and a business guy. People reacted differently to each of them.
WATCH THE FULL VIDEO, SEE HOW PEOPLE REACT AND TEST YOURSELF: