If you saw someone else in trouble, would you simply walk on? That depends mostly on how many people are around. The more people that are present, the less inclined you will be to react yourself. This is the bystander effect, discovered by psychologists Bibb Latané and John Darley following the 1964 Kitty Genovese murder in New York City.
Genovese was stabbed to death outside her apartment, and according to press coverage none of the neighbours reacted despite being fully aware of what was going on. This was not accurate – it was difficult to grasp what was actually going on, and some did call the police - but the neighbours' response was generally half-hearted. One neighbour was stopped by his wife from calling the police, on the grounds that 'someone else is bound to have called'.
A series of classic experiments by Latané and Darley revealed that the amount of time it took a participant to take action varied depending on how many other observers were in the room. Studies also suggested that while 70 per cent would help a woman in distress when they were the only witness, only about 40 per cent offered assistance when other people were present.
Two main factors come into play in the bystander effect. One is the diffusion of responsibility – with many others present, the responsibility is shared throughout the group and no one feels that it's down to them to do anything. The other is our desire to conform and follow the actions of others. When no one else does anything, it's easier to feel that it's not necessary, or even appropriate, to take action. Emergency situations are often unclear or chaotic, and we tend to look to others to decide on the correct action – or inaction.