If you witnessed a murder, would you stop and help? This seems a ridiculous question. Yet in 1964, Kitty Genovese was murdered outside her house and 38 neighbours were said to have been aware of this. All of them chose to do nothing, despite hearing her screams and cries for help, some even seeing the killer drive away. Studies of this case and others led to the development of an important theory in social psychology: the bystander effect.

After being stabbed about 100 feet from her apartment, Kitty screamed: “He stabbed me! Help me!” The man drove away, leaving her to crawl in agony for help, only for the killer to return, sexually assault her and stab her again, before escaping. The crime was reported in the New York Times as “Thirty-Eight Who Saw Murder Didn’t Call the Police” and the lack of reaction and indifference shown by innocent bystanders shocked America. One neighbour was quoted as saying: “I didn’t want to get involved.”

Two psychologists, Latané and Darley, became intrigued by the case, and wanted to understand the behaviour of the group of witnesses. They conducted a series of now classic experiments, which demonstrated the powerful ramifications of the bystander effect. Typically, a participant was placed either alone or in a group and an emergency situation was staged. The researchers then measured how long it took for the participants to intervene, if at all.

The first example involved students discussing their lives in separate rooms, over an intercom. They did not know they were talking to pre-recorded voices; some were under the impression they were alone in the exercise, while some were told there was as many as six other participants. Midway through the discussion, a tape of one participant having an apparent epileptic seizure was played (“I'm... I'm having a fit... I... I think I'm... help me…I…if someone can just help me out here... I... I... can't breathe p-p-properly... I'm going to d-d-die if…”). Despite knowing it was a life-threatening situation, only 31% of participants bothered to seek help, and the majority of these were the subjects from the one-on-one conversation. The bigger groups displayed significantly fewer reactions.

The bystander effect therefore refers to the phenomenon in which the greater the number of people present, the less likely one is to help a person in distress. Two reasons have been offered to explain this, the first being called ‘diffusion of responsibility’, when observers assume that someone else will intervene, and so do not feel responsible themselves. The second reason is called ‘pluralistic ignorance’, the mentality that since no-one else is reacting to an emergency, help is not needed.

We know now that the case of Kitty Genovese as reported by journalists has been somewhat misrepresented, and the existence of the bystander effect itself has been questioned. It has been suggested that people do not act in an emergency situation because they think that other observers may be more qualified to help; for example, if a doctor is present at the scene, the patient may be better off with them.

Despite this, the bystander effect continues to have a powerful impact on social behaviour today, including scandals in hospitals where patients have been left waiting and died whilst crowds of doctors and nurses can see them, and posts on internet chatrooms confessing to murder that have gone unreported, despite hundreds of views. So how can we avoid falling into the trap of apathy? Simply being aware of the phenomenon may just be enough to prevent inaction; if you are the person in need of assistance, singling one person out from the crowd and individualising your request will greatly increase your chances of getting help. These experiments illustrate the worrying concept of social inaction, and how social influence may cloud basic moral judgments.