It can be a worry when someone needs help. Often we feel that we do not want to become involved or we could be frightened that we might get hurt. If their are a lot of people around and they are not helping then it seems correct to not worry and walk passed the person needing help. That's the message we keep hearing but this video explains the situation in detail. It is often referred to as the "Bystander effect"
But it is wrong. They need just one person to start and the help expands quickly. Our separate research it is believed that if one person is on their own they are more likely to help than if there were more people however our experience is that many people do offer to help and in Japan 28% of the population do volunteering work.