Bystander effect is the tendency of a bystander to be less likely to help in an emergency if there are other onlookers present (Kenrick, Neuberg, & Cialdini; 2010). Basically, if there is a crowd of people somewhere and someone, for example, has a stroke, that person may stick there with no help at all. Due to there being so many other people there, less are likely to help the person. The main reason is because everyone believes everyone else will help the person in need.
Diffusion of responsibility is the tendency for each group member to dilute personal responsibility for acting by spreading it among all the other group members (Kenrick, Neuberg, & Cialdini; 2010). Diffusion of responsibility is different than the bystander effect simply because with diffusion of responsibility, no one believes that the person, who needs help, is their responsibility. Say, if the person is someone we don’t know at all, we are less likely to help because we have no obligation to them, not like we would to a friend or family member.
A great example of the bystander effect happened with Catherine (Kitty) Genovese on March 13, 1964 located in Kew Gardens, Queens, NY. She had gotten off work and just arrived to her apartment building, when she was stabbed twice in the back by Winston Moseley.
Genovese had screamed “oh, my God! He stabbed me! Help me!” and then collapsed. Several of her neighbors in surrounding buildings had reported hearing her voice, but none had helped, deciding that it was probably a drunken brawl or lovers’ spat. One man had shouted from his window “Let the girl alone!” which had scared Moseley off.
However, this same neighbor was sure to have seen Genovese crawling across the street, under a streetlight, to her apartment, but had done nothing to help her. Witnesses saw Moseley drive away, and then return 10 minutes later. He had returned with a wider-brimmed hat to hide his face, and searched for Genovese in the parking lot, the train...