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Bystander intervention is a term used to refer to whether individuals help in emergencies, and when they do not, it is known as bystander apathy.
Diffusion of responsibility (and blame) occurs when, at an emergency situation in front of many people, "each individual feels less responsible for taking action than they would if they were the only person available to help" (Burr 2007 p163). In other words, the more people present, the less likely an individual is to help.


Darley and Latanē (1968), after reading of the murder in New York in 1964 of Kitty Genovese where, it is reported, that 38 people heard her cries and nobody helped # (Rosenthal 1964), set up an experiment to test the diffusion of responsibility. 
They used fifty-nine female and thirteen male psychology students at New York University. The participants were placed individually in a small room with a microphone and a pair of headphones. They were led to believe that other individuals were in similar rooms only in contact by the microphone. The task was to discuss the experiences of adjusting to New York city and university life. In fact, the participant was listening to a pre-recording of others talking.
Darley and Latanē created an emergency by the speaker in another room apparently seeming to have an epileptic seizure. The researchers varied the number of people that the participant believed also heard the fit as either two (victim and participant), three or six. The make-up of the supposed groups was varied as female or male. The decision to help by the participants was recorded as to whether they left their room in search of other people within six minutes of the fit.
Significantly more participants responded to help, and quicker, in the two-group condition than the other conditions(85% vs 62% in 3-person condition and 31% in 6-person condition).
The make-up of the supposed group did not influence the decision to help (ie: no gender differences).

Darley and Latanē explained the behaviour of helping or not in terms of an avoidance-avoidance conflict. A conflict between concern "not to make fools of themselves by overreacting, not to ruin the ongoing experiment by leaving their intercom, and not to destroy the anonymous nature of the situation which the experimenter had earlier stressed as important" and "the guilt and shame they would feel if they did not help the person in distress". In the two-person condition, the latter aspect is more important and individuals help. In the larger group conditions, the cost of not helping is less, and the conflict remains which inhibits the motivation to help.


  1. Ethics of the study

    All but two of the participants were surprised to find out after the experiment that the epileptic seizure was simulated. The responses of the participants were recorded on the microphone and showed genuine concern, like "My God, he's having a fit" or "Oh God, what should I do?". Participants whether they helped or not showed signs of nervousness including trembling hands and sweating palms. This study, then, caused the participants distress as well as deceiving them. In a post-experimental questionnaire, participants were positive about their experiences of the experiment.

  2. Situational basis to bystander intervention and apathy

    This study along with others by Latanē and Darley (eg: 1970) showed that the decision to help in an emergency is influenced by situational factors, like the presence of other people. It challenged the "common sense" explanations for the failure to help Kitty Genovese that included "moral decay", "depersonalised by living in the cold society" or personality variables like "psychopaths". Darley and Latanē (1968) concluded:

    The explanation of bystander apathy may lie more in the bystander's response to other observers than in presumed personality deficiencies of "apathetic" individuals. Although this realisation may force us to face the guilt-provoking possibility that we too might fail to intervene, it also suggests that individuals are not, of necessity, "non-interveners" because of their personalities (p383).

  3. Experimental situation

    Studying bystander intervention and apathy in a laboratory experiment has both advantages and disadvantages. The advantages include control of incident variables that may "contaminate" the results, and the ability to establish cause and effect. But the main disadvantage is that the study is artificial and it is not a real-life event. In particular, Cherry (1995) argued that this research in relation to Kitty Genovese's murder was "stripped of its original gendered parts, that is, an attack on a woman was no longer an essential component in the laboratory exploration of what the event meant". In other words, Kitty Genovese was attacked in a society at a time when little was done to stop violence against women. In fact, one of the onlookers admitted not wanting to get involved because they thought it was a "lover's quarrel" (Rasenberg 2004). Laboratory experiments cannot capture this "social embededness". The experiment with its concern with "a dispassionate detachment from the research material and from individual participants; instead of producing 'objectivity' it is argued that scientific language and experimental procedure serves only to mask the values and assumptive world of the researcher" (Burr 2007 p186).


Burr, V (2007) Bystander intervention. In Langridge, D & Taylor, S (eds) Critical Readings in Social Psychology.  Maidenhead: Open University Press

Cherry, F (1995) Kitty Genovese and culturally embedded theorising. In Cherry, F (ed) The Stubborn Particulars of Social Psychology: Essays on the Research Process. London: Routledge

Darley, J.M & Latanē, B (1968) Bystander intervention in emergencies: Diffusion of responsibility. Journal of Personality and Social Psychology, 3, 4, 377-383

Latanē, B & Darley, J.M (1970) The Unresponsive Bystander: Why Doesn't He Help?  New York: Meredith

Manning, R et al (2007) The Kitty Genovese murder and the social psychology of helping: The parable of the thirty-eight witnesses. American Psychologist, 62, 6, 555-562

Rasenberg, J (2004) Kitty, forty years later. New York Times:  <> (accessed 01/10/08)

Rosenthal, A.M (1964) Thirty-Eight Witnesses. New York: McGraw-Hill
changed September 15, 2010