In 1964, the stabbing of a 28-year old woman coming home from work one night in New York City prompted the world to ask why otherwise well-meaning people sometimes let horrible things happen. 38 witnesses to the murder of that woman stood by, making no effort to interfere with the killer (Gansberg M., 1964). The idea that someone could be killed and people would stand idly by became something psychologists were very concerned. They began to research and later launched a whole new field of study that became known as the Bystander effect. The fundamental idea behind this principle is that an individual in a larger crowd is, contrary to popular belief, less likely to receive aid and assistance than in a smaller crowd (Darley & Latané, 1968). Kitty Genovese's death and hence the concept of the Bystander effect became the textbook example of passive group behavior, bearing considerable importance in the field of contemporary psychology as it has not only been credited with helping spur Good Samaritan laws in many US states but also for making people think critically about why they don't always do as much to help as they think they should. .
In 1968 John Darley and Bibb Latané (Latané, B. & Darley, 1968) took subjects, put headphones on them, took them in a room and asked them to listen to other people. They were made to feel that they were either alone, with two other people or with five others. The two distinguished social psychologists tried something very traumatic. They had the experimental subjects listen to someone describing the symptoms of a stroke and then desperately calling out for help. What they were interested in was to find out whether the individual with headphones on, alone in a room would yell out for help or even break the bounds of the experiment to offer help. As expected, it was found that in a 6 minute period following the onset of the individual describing stroke symptoms, when a person was made to feel alone, over 80% helped within a 6 minute time window.