Background: In this study Piliavin, Rodin and Piliavin carried out a field experiment to investigate helping behaviour towards different types of victims. Piliavin et al. note in their study that social psychologists became particularly interested in the behaviour of bystanders following the case of the brutal murder of Kitty Genovese in New York in 1964. The murder attracted interest from psychologists because according to the press not one person out of the 40 people, who witnessed the attack lasting over half an hour, tried to help or contacted the police. Many laboratory studies were carried out by social psychologists to test bystander apathy. That is. the phenomenon of when observers of an emergency situation do not intervene. Importantly social psychologists looked for the cause of bystander behaviour not in the type of people who do or do not help but in the situational factors which influence helping behaviour. The early laboratory experiments into bystander apathy consisted of candid camera/trigger happy style scenarios where people were placed in situations such as a smoke filled room to investigate if people would sound the alarm or not. (e.g. Latane and Darley 1968). These experiments usually consisted of one participant and a number of confederates. One of the findings of such laboratory experiments was that people did demonstrate diffusion of responsibility. That is they were less likely to help as the number of bystanders increased. However Piliavin et al. recognised that these laboratory experiments lacked ecological validity in that they did not demonstrate how people would react in a realistic situation. They therefore planned to investigate helping behaviour using a field experiment where they could observe behaviour as it is in the real everyday world.