Actually they want to help, but they are afraid of being embarassed infront of 100 people.If you fall down and a stranger beside you comes and both of you are the only people at during that time, i bet you the chances are higher that he/she will help because no "embarassment" is invovled.
thanks for telling me something I already knew.
Diffusion of responsibility is a social phenomenon which tends to occur in groups of people above a certain critical size when responsibility is not explicitly assigned.
Diffusion of responsibility can manifest itself
* in a group of peers who act or, through inaction, allow events to occur which they would never allow if alone (see bystander apathy for an example) or
* in hierarchical organizations as when, for example, underlings claim that they were following orders and supervisors claim that they were just issuing directives and not doing anything per se.