Key Takeaways
- Bystander Effect: People are less likely to help someone in distress when other people are present. The more bystanders there are, the lower each person’s chance of helping.
- Diffusion of Responsibility: Bystanders subjectively split the responsibility to help by the number of people present, so each person feels less personally accountable.
- Kitty Genovese: The most cited real-life example is Kitty Genovese, murdered in Queens in 1964. Later historical analysis found the “38 witnesses who did nothing” story was exaggerated.
- Five-Step Model: Latané and Darley (1970) proposed bystanders must notice, interpret, take responsibility, decide how to help, and act — hesitation at any step blocks helping.
- Three Processes: Diffusion of responsibility, evaluation apprehension, and pluralistic ignorance each help explain why people fail to help when others are present.
- Modern Evidence: A 2011 meta-analysis of over 7,700 participants confirmed the effect is real but modest, and CCTV footage shows bystanders intervene in the large majority of genuine public conflicts.
What is the bystander effect?
The bystander effect is the tendency for people to be less likely to help someone in distress when other people are present (Darley & Latané, 1968).
People are more likely to help when alone than in a group. Interest in this phenomenon grew sharply after the murder of Catherine “Kitty” Genovese in 1964, and a series of experiments in the 1960s and 1970s went on to explain why.
Kitty Genovese
On the morning of March 13, 1964, Kitty Genovese returned to her apartment complex, at 3 am, after finishing her shift at a local bar.
After parking her car in a lot adjacent to her apartment building, she began walking a short distance to the entrance, which was located at the back of the building.
As she walked, she noticed a figure at the far end of the lot. She shifted directions and headed towards a different street, but the man followed and seized her.
As she screamed, Robert Mozer, a neighbor, shouted from his window, “Let that girl alone!” The attacker was Winston Moseley. He fled to his car.
Genovese, badly wounded, staggered to the back of her building and collapsed in a small entryway, out of view of the street. Ten minutes later, Moseley came back and found her.
He attacked her a second and final time, stabbing her repeatedly. The first call to the police came in at approximately 3:50 am; officers arrived within two minutes, but Genovese died on the way to the hospital. Moseley was arrested six days later and confessed.
When asked later why they had not intervened or called the police sooner, the neighbors gave several answers. Some said, “I didn’t want to get involved”; others said, “Frankly, we were afraid,” or “I was tired. I went back to bed.” (New York Times, 1964).
After this initial report, the case was launched to nationwide attention, with various leaders commenting on the apparent “moral decay” of the country.
In response to these claims, Darley and Latané set out to find an alternative explanation.
Decision Model of Helping
Latané & Darley (1970) formulated a five-stage model to explain why bystanders in emergencies sometimes do and sometimes do not offer help.
At each stage in the model, the answer ‘No’ results in no help being given, while the answer ‘yes’ leads the individual closer to offering help.
However, they argued that helping responses may be inhibited at any stage of the process. For example, the bystander may not notice the situation or the situation may be ambiguous and not readily interpretable as an emergency.
The Five Steps of the Decision Model
- Notice: The bystander must notice that something is wrong.
- Interpret: The bystander must define the situation as an emergency.
- Take Responsibility: The bystander must decide they are personally responsible for helping.
- Decide How to Help: The bystander must work out the best way to assist.
- Act: The bystander must follow through and provide the help decided on.
Figure 1. Decision Model of Helping by Latané and Darley (1970).
Why does the bystander effect occur?
Latané and Darley (1970) identified three different psychological processes that might interfere with the completion of this sequence.
Diffusion of Responsibility
The first process is a diffusion of responsibility, which refers to the tendency to subjectively divide the personal responsibility to help by the number of bystanders.
Diffusion of responsibility occurs when a duty or task is shared between a group of people instead of only one person.
Whenever there is an emergency situation in which more than one person is present, there is a diffusion of responsibility. There are three ideas that categorize this phenomenon:
- The moral obligation to help does not fall only on one person but the whole group that is witnessing the emergency.
- The blame for not helping can be shared instead of resting on only one person.
- The belief that another bystander in the group will offer help.
Aim: Darley and Latané (1968) isolated diffusion of responsibility from social influence, testing whether the number of unseen, unheard bystanders affected how quickly someone helped.
Method: 72 students took part in what they thought was a discussion over an intercom about university life. Each heard a recording of a “victim” having a seizure, believing one, two, or four other people were also listening but unable to see or hear them.
Results: The pattern was stark. In two-person groups, 85% reported the seizure; that fell to 62% in three-person groups and just 31% in six-person groups. Response times rose from 52 seconds to 93 seconds to 166 seconds as group size grew, and personality traits did not predict who helped.
Conclusion: Not pluralistic ignorance. The drop in helping came from diffusion of responsibility: bystanders could not see each other, so each felt less accountable in a larger group.
Participants who did not help were not indifferent. They showed visible nervousness, suggesting they were still struggling to decide what to do rather than ignoring the emergency.
Evaluation Apprehension
The second process is evaluation apprehension, which refers to the fear of being judged by others when acting publicly.
People may also experience evaluation apprehension and fear of losing face in front of other bystanders.
Individuals may also fear being superseded by a more capable helper, offering unwanted assistance, or facing legal consequences for offering inferior or unsafe help.
Pluralistic Ignorance
The third process is pluralistic ignorance, which results from the tendency to rely on the overt reactions of others when defining an ambiguous situation.
Pluralistic ignorance occurs when a person privately disagrees with an idea but believes everyone else accepts it. As a result, they go along with that idea too, even though no one actually believes it.
Deborah A. Prentice cites an example of this. Despite being in a difficult class, students may not raise their hands in response to the lecturer asking for questions.
This is often due to the belief that everyone else understands the material, so for fear of looking inadequate, no one asks clarifying questions.
It is this type of thinking that explains the effect of pluralistic ignorance on the bystander effect. The overarching idea is uncertainty and perception. What separates pluralistic ignorance is the ambiguousness that can define a situation.
If the situation is clear, pluralistic ignorance does not apply. In the classroom example, if someone states they do not understand, everyone now knows someone else agrees with them.
It is the ambiguity and uncertainty which leads to incorrect perceptions that categorize pluralistic ignorance.
Rendsvig (2014) proposes an eleven-step process to explain this phenomenon.
These steps follow the perspective of a bystander (who will be called Bystander A) amidst a group of other bystanders in an emergency situation.
- Bystander A is present in a specific place. Nothing has happened.
- A situation occurs that is ambiguous in nature (it is not certain what has occurred or what the ramifications of the event are), and Bystander A notices it.
- Bystander A believes that this is an emergency situation but is unaware of how the rest of the bystanders perceive the situation.
- A course of action is taken. This could be a few things like charging into the situation or calling the police, but in pluralistic ignorance, Bystander A chooses to understand more about the situation by looking around and taking in the reactions of others.
- As observation takes place, Bystander A is not aware that the other bystanders may be doing the same thing. Thus, when surveying others’ reactions, Bystander A “misperceives” the other bystanders” observation of the situation as purposeful inaction.
- As Bystander A notes the reaction of the others, Bystander A puts the reaction of the other bystanders in context.
- Bystander A then believes that the inaction of others is due to their belief that an emergency situation is not occurring.
- Thus, Bystander A believes that there is an accident but also believes that others do not perceive the situation as an emergency. Bystander A then changes their initial belief.
- Bystander A now believes that there is no emergency.
- Bystander A has another opportunity to help.
- Bystander A chooses not to help because of the belief that there is no emergency.
Pluralistic ignorance operates under the assumption that all the other bystanders are also going through these eleven steps.
Thus, they all choose not to help due to the misperception of others’ reactions to the same situation.
Other Explanations
While these three are the most widely known explanations, there are other theories that could also play a role. One example is a confusion of responsibility.
Confusion of responsibility occurs when a bystander fears that helping could lead others to believe that they are the perpetrator. This fear can cause people to not act in dire situations.
Another example is priming: giving a person cues that influence later, unrelated actions. For example, someone shown a list of home-decor words is more likely to answer “chair” or “table” than “pasta” when later asked for any five-letter word.
In social situations, Garcia et al. found that simply thinking of being in a group could lead to lower rates of helping in emergency situations. This occurs because groups are often associated with “being lost in a crowd, being deindividuated, and having a lowered sense of personal accountability” (Garcia et al., 2002, p. 845).
Thus, the authors argue that the way a person was primed could also influence their ability to help. These alternate theories highlight the fact that the bystander effect is a complex phenomenon that encompasses a variety of ideologies.
Bystander Experiments
Two further experiments show how ambiguity and personal relationships shape whether bystanders act.
The Smoke Study: Pluralistic Ignorance in Action
Aim: Latané and Darley (1968) tested whether the presence of other people stops someone interpreting an ambiguous event as an emergency, a mechanism later called pluralistic ignorance.
Method: The setup was simple. Male students completed a questionnaire alone, with two passive confederates, or with two other real participants, while smoke drifted into the room through a wall vent.
Results: 75% of participants alone reported the smoke, half within two minutes. With two passive confederates who ignored it, only 10% reported it, and among groups of three real participants, only 38% of the groups produced any reporter at all.
Conclusion: Non-reporters were not indifferent. They had reinterpreted the smoke as steam or vapor, having looked to others’ calm reactions for cues about the ambiguous situation.
This is a clear example of pluralistic ignorance, affecting step 2 of the Latané and Darley decision model above.
Ambiguity in Domestic Violence
Genuine ambiguity, not just other people’s presence, can affect whether someone helps. Context matters. Shotland and Straw (1976) tested this in a staged domestic dispute versus a stranger attack.
Male participants watched a staged fight between a man and a woman. She shouted either ‘I don’t even know you’ or ‘I don’t even know why I married you.’ The wording alone mattered.
Three times as many men intervened when the couple appeared to be strangers than when they appeared to be a couple. Bystanders read the apparent relationship between victim and attacker as a cue to how much the situation called for outside help.
People are less likely to intervene if they believe that the incident does not require their personal responsibility.
The finding supports the model’s third step. An ambiguous relationship makes personal responsibility harder to accept, since a bystander may assume a domestic dispute is “not their business.”
Critical Evaluation
While the bystander effect has become a cemented theory in social psychology, the original account of the murder of Catherine Genovese has been called into question. By casting doubt on the original case, the implications of the Darley and Latané research are also questioned.
Manning et al. (2007) did this through their article “The Kitty Genovese murder and the social psychology of helping, The parable of the 38 witnesses”. By examining the court documents and legal proceedings from the case, the authors found three points that deviate from the traditional story told.
The “38” figure appears nowhere in the police record. It was a number generated in the New York Times newsroom, and its authority came from the headline rather than from any source.
Very few people saw any part of the attack, and effectively no one saw the killing itself. The fatal, second stabbing happened inside a small vestibule invisible from almost every apartment window identified as a “witness.”
The traditional story also overstates the neighbors’ inaction. At least two people did call the police, and one man shouted from his window and drove the attacker off.
The potential inaccurate reporting has not negated the bystander effect completely. But it has called into question the case’s evidential value and narrowed the questions the field went on to ask.
Limitations of the Decision-Helping Model
Schroeder et al. (1995) believe that the decision-helping model provides a valuable framework for understanding bystander intervention.
Although developed to explain emergencies, the model has since been applied elsewhere, from preventing drunk driving to deciding whether to donate a kidney to a relative.
The model has limits, though. It does not explain why a “no” decision happens at each stage, especially once someone has already interpreted the event as an emergency.
It also leaves out emotional factors like anxiety or fear, and focuses mainly on why people fail to help rather than why they do.
Piliavin et al. (1969, 1981) put forward the cost–reward arousal model as a major alternative to the decision model and involves evaluating the consequences of helping or not helping.
Whether one helps or not depends on the outcome of weighing up both the costs and rewards of helping. The costs of helping include effort, time, loss of resources, risk of harm, and negative emotional response.
The rewards of helping include fame, gratitude from the victim and relatives, and self-satisfaction derived from the act of helping. It is recognized that costs may be different for different people and may even differ from one occasion to another for the same person.
Accountability Cues
According to Bommel et al. (2012), the negative framing of the bystander effect undermines its potential positives. Crowds are not always bad news.
Their study, “Be aware to care: Public self-awareness leads to a reversal of the bystander effect,” shows crowds can actually increase help given to a victim under certain conditions.
One problem with bystanders in emergencies is that responsibility can be split, diffusing it across the group. But “accountability cues” can reverse this. These are specific markers, like a visible camera, that signal a bystander’s actions are being watched.
The researchers created an online forum for people seeking help with “severe emotional distress.” Participants responded to visitors’ messages and rated how visible they felt on the forum.
Visibility was the key manipulation.
With no accountability cues, people gave less help and rated themselves as less visible. With cues present, such as a webcam and the visitor’s name displayed, more people helped and rated their presence on the forum as higher.
The results matched these predictions. Targeting a person’s reputation through accountability cues can increase helping, showing the bystander effect can be reversed.
Neuroimaging Evidence
Researchers looked at the regions of the brain that were active when a participant witnessed emergencies. They noticed that less activity occurred in the regions that facilitate helping: the pre- and postcentral gyrus and the medial prefrontal cortex (Hortensius et al., 2018).
Thus, one’s initial biological response to an emergency situation is inaction due to personal fear. After that initial fear, sympathy arises, which prompts someone to go to the aid of the victim. These two systems work in opposition; whichever overrides the other determines the action that will be taken.
If there is more sympathy than personal distress, the participant will help. Thus, these researchers argue that the decision to help is not “reflective” but “reflexive” (Hortensius et al., 2018).
With this in mind, the researchers argue for a more personalized view that takes into account one’s personality and disposition to be more sympathetic rather than utilize a one-size-fits-all overgeneralization.
Contemporary Research
Two large studies published after 2010 have reshaped this picture. One confirms the bystander effect statistically. The other says it’s far rarer outside the lab.
The 2011 Meta-Analysis
Aim: Fischer et al. (2011) ran the first modern meta-analysis of the bystander effect, testing whether it survives in dangerous as well as ambiguous emergencies.
Method: The researchers pooled 105 independent effect sizes from more than 7,700 participants across five decades of studies. They tested moderators including perceived danger, the presence of a perpetrator, and the type of costs involved in helping.
Results: The overall effect was small-to-moderate (g = -0.35). It shrank significantly in dangerous emergencies, when a perpetrator was physically present, and when the cost of helping was physical rather than emotional or financial.
Conclusion: The effect is real but modest, far smaller than the dramatic 1960s lab contrasts. In real danger, extra bystanders can help, not hinder.
Real-World Evidence from CCTV Footage
Philpot et al. (2020) analyzed CCTV footage of 219 real public conflicts in Amsterdam, Cape Town, and Lancaster. At least one bystander intervened in 90.9% of incidents, with an average of 3.76 people stepping in per event. Each additional bystander made help slightly more likely, not less.
This suggests the classic “unresponsive bystander” pattern is largely a feature of the ambiguous, low-stakes laboratory paradigm. In real public emergencies, the norm is intervention, not inaction.
References
Darley, J. M., & Latané, B. (1968). Bystander intervention in emergencies: Diffusion of responsibility. Journal of Personality and Social Psychology, 8, 377–383.
Fischer, P., Krueger, J. I., Greitemeyer, T., Vogrincic, C., Kastenmüller, A., Frey, D., Heene, M., Wicher, M., & Kainbacher, M. (2011). The bystander-effect: A meta-analytic review on bystander intervention in dangerous and non-dangerous emergencies. Psychological Bulletin, 137 (4), 517–537.
Garcia, Stephen M, Weaver, Kim, Moskowitz, Gordon B, & Darley, John M. (2002). Crowded Minds. Journal of Personality and Social Psychology, 83 (4), 843-853.
Hortensius, Ruud, & De Gelder, Beatrice. (2018). From Empathy to Apathy: The Bystander Effect Revisited. Current Directions in Psychological Science, 27 (4), 249-256.
Latané, B., & Darley, J. M. (1968). Group inhibition of bystander intervention in emergencies. Journal of Personality and Social Psychology, 10, 215–221.
Latané, B., & Darley, J. M. (1970). The unresponsive bystander: Why doesn’t he help? New York, NY: Appleton-Century-Croft.
Latané, B., & Darley, J. M. (1976). Help in a crisis: Bystander response to an emergency . Morristown, NJ: General Learning Press.
Latané, B., & Nida, S. (1981). Ten years of research on group size and helping. Psychological Bulletin, 89, 308 –324.
Manning, R., Levine, M., & Collins, A. (2007). The Kitty Genovese murder and the social psychology of helping: The parable of the 38 witnesses. American Psychologist, 62, 555-562.
Philpot, R., Liebst, L. S., Levine, M., Bernasco, W., & Lindegaard, M. R. (2020). Would I be helped? Cross-national CCTV footage shows that intervention is the norm in public conflicts. American Psychologist, 75 (1), 66–75.
Prentice, D. (2007). Pluralistic ignorance. In R. F. Baumeister & K. D. Vohs (Eds.), Encyclopedia of social psychology (Vol. 1, pp. 674-674). Thousand Oaks, CA: SAGE Publications, Inc.
Rendsvig, R. K. (2014). Pluralistic ignorance in the bystander effect: Informational dynamics of unresponsive witnesses in situations calling for intervention. Synthese (Dordrecht), 191 (11), 2471-2498.
Shotland, R. L., & Straw, M. K. (1976). Bystander response to an assault: When a man attacks a woman. Journal of Personality and Social Psychology, 34 (5), 990.
Siegal, H. A. (1972). The Unresponsive Bystander: Why Doesn’t He Help? 1(3), 226-227.
Van Bommel, Marco, Van Prooijen, Jan-Willem, Elffers, Henk, & Van Lange, Paul A.M. (2012). Be aware to care: Public self-awareness leads to a reversal of the bystander effect. Journal of Experimental Social Psychology, 48 (4), 926-930.
