The bystander effect or Genovese syndrome is a social psychological phenomenon that refers to cases where individuals do not offer any means of help in an emergency situation to the victim when other people are present. The probability of help has in the past been thought to be inversely related to the number of bystanders; in other words, the greater the number of bystanders, the less likely it is that any one of them will help.
In 1968 a number of researchers launched a series of experiments that resulted in one of the strongest and most replicable effects in social psychology.
In a typical experiment, the participant is either alone or among a group of other participants or confederates. An emergency situation is then staged—examples include smoke pouring from a vent in the room, a person falling and becoming injured, a student having an epileptic seizure, etcetera. The researchers then measure how long it takes the participants to act, and whether or not they intervene at all. These experiments virtually always find that the presence of others inhibits helping, often by a large margin.
There are, in fact, many reasons why bystanders in groups fail to act in emergency situations, but social psychologists have focused most of their attention on two major factors. According to a basic principle of social influence, bystanders monitor the reactions of other people in an emergency situation to see if others think that it is necessary to intervene. Since everyone is doing exactly the same thing – which is nothing – they all conclude from the inaction of others that help is not needed. This is an example of pluralistic ignorance or social proof. The other major obstacle to intervention is known as diffusion of responsibility. This occurs when observers all assume that someone else is going to intervene and so each individual feels less responsible and refrains from doing anything.
There are other reasons why people may not help. They may assume that other bystanders are more qualified to help, such as doctors or police officers, and that their intervention would be unneeded. People may also experience evaluation apprehension and fear losing face in front of the other bystanders. They may also be afraid of being superseded by a superior helper, offering unwanted assistance, or facing the legal consequences of offering inferior and possibly dangerous assistance. An example is the so-called Good Samaritan Law, limiting liability for those attempting to provide medical services as opposed to non-medical services.