The Bystander Effect and Altruism

Learning Objectives

  • Explain the factors that influence human altruism, including reciprocal altruism and diffusion of responsibility.

Go to YouTube and search for episodes of “Primetime: What Would You Do?” You will find video segments in which apparently innocent individuals are victimized, while onlookers typically fail to intervene. The events are all staged, but they are very real to the bystanders on the scene. The entertainment offered is the nature of the bystanders’ responses, and viewers are outraged when bystanders fail to intervene. They are convinced that they would have helped. But would they? Viewers are overly optimistic in their beliefs that they would play the hero. Helping may occur frequently, but help is not always given to those in need. So when do people help, and when do they not? All people are not equally helpful—who helps? Why would a person help another in the first place? Many factors go into a person’s decision to help—a fact that the viewers do not fully appreciate. This module will answer the question: Who helps when and why?

A man walks arm in arm with an elderly man, while another woman approaches as if to offer help as well. Yet another woman walks by smiling at the altruistic behavior.

Figure 1. People often overestimate their willingness to help others in need especially when they are asked about a hypothetical situation rather than encountering one in real life. [Image: Ed Yourdon]

When Do People Help?

Social psychologists began trying to answer this question following the unfortunate murder of Kitty Genovese in 1964 (Dovidio, Piliavin, Schroeder, & Penner, 2006; Penner, Dovidio, Piliavin, & Schroeder, 2005). A knife-wielding assailant attacked Kitty repeatedly as she was returning to her apartment early one morning. At least 38 people may have been aware of the attack, but no one came to save her. Based on this case, researchers Latané and Darley (1968) described a phenomenon called the bystander effect. The bystander effect is a phenomenon in which a witness or bystander does not volunteer to help a victim or person in distress. Instead, they just watch what is happening. Social psychologists hold that we make these decisions based on the social situation, not our own personality variables. Why do you think the bystanders didn’t help Genovese? What are the benefits to helping her? What are the risks? It is very likely you listed more costs than benefits to helping. In this situation, bystanders likely feared for their own lives—if they went to her aid the attacker might harm them. However, how difficult would it have been to make a phone call to the police from the safety of their apartments? Why do you think no one helped in any way?

New Understanding of The Kitty Genovese Case

Two weeks after the murder of Kitty Genovese, The New York Times published an article erroneously claiming that 38 witnesses saw or heard the attack, and that none of them called the police or came to her aid. The incident prompted inquiries into what became known as the bystander effect and the murder has became a staple in U.S. psychology textbooks like this one. However, researchers have since uncovered major inaccuracies in The New York Times article.

Police interviews revealed that some witnesses had attempted to call the police. In 2007, an article in the American Psychologist found “no evidence for the presence of 38 witnesses, or that witnesses observed the murder, or that witnesses remained inactive.”[1] In 2016, the Times called its own reporting “flawed”, stating that the original story “grossly exaggerated the number of witnesses and what they had perceived.”[2] What Kitty Genovese’s case does reveal, perhaps even more than an argument for bystander intervention, is the power of influence and coercion, as the convicted murderer, Winston Moseley, also confessed to two other murders but the police had already solicited false confessions for those murders from other people.[3] A 29-year-old Manhattan native, he was arrested during a house burglary six days after the murder. At his trial, Moseley was found guilty of murder and sentenced to death; this sentence was later commuted to life imprisonment. Moseley died in prison on March 28, 2016, at the age of 81, having served 52 years.

Despite the inaccuracies of this specific case, the bystander effect phenomenon remains pertinent and can be seen in many instances since that time.

More recently, on October 24, 2009, a female student of Richmond High School was gang-raped and beaten by a group of boys and men after a classmate invited her to a dark courtyard outside the school’s homecoming dance. It was reported that she was treated politely and drank brandy with the group before the assault took place, which lasted two and a half hours before a young woman notified the police. As many as 20 people witnessed the incident, with several reportedly cheering and videotaping it. The case drew nationwide outrage.

In 2010, Hugo Alfredo Tale-Yax was stabbed when he apparently tried to intervene in an argument between a man and woman. As he lay dying in the street, only one man checked his status, but many others simply glanced at the scene and continued on their way. (One passerby did stop to take a cellphone photo, however.)

On Memorial Day, 2011, 53-year-old Raymond Zack, of Alameda, California, walked into the waters off Robert Crown Memorial Beach and stood neck-deep in water roughly 150 yards offshore for almost an hour. His foster mother, Dolores Berry, called 9-1-1 and said that he was trying to drown himself. (There are conflicting reports about Zack’s intentions.) Firefighters and police responded but did not enter the water. The firefighters called for a United States Coast Guard boat to respond to the scene. According to police reports, Alameda police expected the firefighters to enter the water. Firefighters later said that they did not have current training and certifications to perform land-based water rescue. Dozens of civilians on the beach, and watching from their homes across from the beach, did not enter the water, apparently expecting public safety officers to conduct a rescue. Eventually, Zack collapsed in the water, apparently from hypothermia. Even then, nobody entered the water for several minutes. Finally, a good samaritan entered the water and pulled Zack to shore. Zack died afterward at a local hospital.

There was an increase in hate crimes against Asian-Americans in the United States following the outbreak of the Covid-19 pandemic. In March 2021, a 65-year old woman was attacked and stomped on in a racially-charged attack while security cameras showed at least three men looking on and walking by, who initially did nothing to help. Another type of bystander inaction can happen digitally as well, like when a sexual assault of a 15-year old was recorded on Facebook Live, but none of the forty or more viewers called the police.

Unfortunately, failures to come to the aid of someone in need are not rare, as the segments on “What Would You Do?” show, but recent studies reveal that a majority of the time, people do intervene. In 2019, cultural anthropologist Marie Rosenkrantz Lindegaard led a large international study, analyzing 219 street disputes and confrontations that were recorded by security cameras in three cities in different countries — Lancaster, England; Amsterdam, Netherlands; and Cape Town, South Africa. Contrary to bystander theory, Lindegaard’s team found that bystanders intervened in almost every case, and the chance of intervention went up with the number of bystanders, which she called “a highly radical discovery and a completely different outcome than theory predicts.”

This study is the first large-scale test of the bystander effect in real-life. Up until now, this effect was mainly studied in the lab by asking study subjects how they would respond in a particular situation. Another striking aspect of this study is that the observations come from three different countries including the violent country of South Africa where intervening in a street dispute is not without risk. ‘That appears to indicate that this is a universal phenomenon’, says Lindegaard.[4]

Despite this, we know that help does not always come for those who may need it the most. Trying to understand why people do not always help became the focus of bystander intervention research (e.g., Latané & Darley, 1970).

To answer the question regarding when people help, researchers have focused on

  1. how bystanders come to define emergencies,
  2. when they decide to take responsibility for helping, and
  3. how the costs and benefits of intervening affect their decisions of whether to help.

Defining the Situation: The Role of Pluralistic Ignorance

The decision to help is not a simple yes/no proposition. In fact, a series of questions must be addressed before help is given—even in emergencies in which time may be of the essence. Sometimes help comes quickly; an onlooker recently jumped from a Philadelphia subway platform to help a stranger who had fallen on the track. Help was clearly needed and was quickly given. But some situations are ambiguous, and potential helpers may have to decide whether a situation is one in which help, in fact, needs to be given.

To define ambiguous situations (including many emergencies), potential helpers may look to the action of others to decide what should be done. But those others are looking around too, also trying to figure out what to do. Everyone is looking, but no one is acting! Relying on others to define the situation and to then erroneously conclude that no intervention is necessary when help is actually needed is called pluralistic ignorance (Latané & Darley, 1970). When people use the inactions of others to define their own course of action, the resulting pluralistic ignorance leads to less help being given.

Do I Have to Be the One to Help?: Diffusion of Responsibility

Overhead photograph of a large crowd.

Figure 2. How does being in a crowd decrease someone’s chance of being helped? How does being in a crowd increase someone’s chance of being helped? [Image: flowcomm]

Simply being with others may facilitate or inhibit whether we get involved in other ways as well. In situations in which help is needed, the presence or absence of others may affect whether a bystander will assume personal responsibility to give the assistance. If the bystander is alone, personal responsibility to help falls solely on the shoulders of that person. But what if others are present? Although it might seem that having more potential helpers around would increase the chances of the victim getting help, the opposite is often the case. Knowing that someone else could help seems to relieve bystanders of personal responsibility, so bystanders do not intervene. This phenomenon is known as diffusion of responsibility (Darley & Latané, 1968).

On the other hand, watch the video of the race officials following the 2013 Boston Marathon after two bombs exploded as runners crossed the finish line. Despite the presence of many spectators, the yellow-jacketed race officials immediately rushed to give aid and comfort to the victims of the blast. Each one no doubt felt a personal responsibility to help by virtue of their official capacity in the event; fulfilling the obligations of their roles overrode the influence of the diffusion of responsibility effect.

There is an extensive body of research showing the negative impact of pluralistic ignorance and diffusion of responsibility on helping (Fisher et al., 2011), in both emergencies and everyday need situations. These studies show the tremendous importance potential helpers place on the social situation in which unfortunate events occur, especially when it is not clear what should be done and who should do it. Other people provide important social information about how we should act and what our personal obligations might be. But does knowing a person needs help and accepting responsibility to provide that help mean the person will get assistance? Not necessarily.

The Costs and Rewards of Helping

The nature of the help needed plays a crucial role in determining what happens next. Specifically, potential helpers engage in a cost–benefit analysis before getting involved (Dovidio et al., 2006). If the needed help is of relatively low cost in terms of time, money, resources, or risk, then help is more likely to be given. Lending a classmate a pencil is easy; confronting the knife-wielding assailant who attacked Kitty Genovese is an entirely different matter. As the unfortunate case of Hugo Alfredo Tale-Yax demonstrates, intervening may cost the life of the helper.

The potential rewards of helping someone will also enter into the equation, perhaps offsetting the cost of helping. Thanks from the recipient of help may be a sufficient reward. If helpful acts are recognized by others, helpers may receive social rewards of praise or monetary rewards. Even avoiding feelings of guilt if one does not help may be considered a benefit. Potential helpers consider how much helping will cost and compare those costs to the rewards that might be realized; it is the economics of helping. If costs outweigh the rewards, helping is less likely. If rewards are greater than cost, helping is more likely.

Why Help?

Finally, the question of why a person would help needs to be asked. What motivation is there for that behavior? Psychologists have suggested that 1) evolutionary forces may serve to predispose humans to help others, 2) egoistic concerns may determine if and when help will be given, and 3) selfless, altruistic motives may also promote helping in some cases.

Evolutionary Roots for Prosocial Behavior

Our evolutionary past may provide keys about why we help (Buss, 2004). Our very survival was no doubt promoted by the prosocial relations with clan and family members, and, as a hereditary consequence, we may now be especially likely to help those closest to us—blood-related relatives with whom we share a genetic heritage. According to evolutionary psychology, we are helpful in ways that increase the chances that our DNA will be passed along to future generations (Burnstein, Crandall, & Kitayama, 1994)—the goal of the “selfish gene” (Dawkins, 1976). Our personal DNA may not always move on, but we can still be successful in getting some portion of our DNA transmitted if our daughters, sons, nephews, nieces, and cousins survive to produce offspring. The favoritism shown for helping our blood relatives is called kin selection (Hamilton, 1964).

Cave drawings of people.

Figure 3. Evolutionary theory suggests that being a good helper was a benefit for survival and reproductive success. And we don’t just help our family members, reciprocal altruism has also been a benefit to our survival. [Image: TimJN1,, CC BY-SA 2.0,]

But, we do not restrict our relationships just to our own family members. We live in groups that include individuals who are unrelated to us, and we often help them too. Why? Reciprocal altruism (Trivers, 1971) provides the answer. Because of reciprocal altruism, we are all better off in the long run if we help one another. If helping someone now increases the chances that you will be helped later, then your overall chances of survival are increased. There is the chance that someone will take advantage of your help and not return your favors. But people seem predisposed to identify those who fail to reciprocate, and punishments including social exclusion may result (Buss, 2004). Cheaters will not enjoy the benefit of help from others, reducing the likelihood of the survival of themselves and their kin.

Evolutionary forces may provide a general inclination for being helpful, but they may not be as good an explanation for why we help in the here and now. What factors serve as proximal influences for decisions to help?

Egoistic Motivation for Helping

Most people would like to think that they help others because they are concerned about the other person’s plight. In truth, the reasons why we help may be more about ourselves than others: Egoistic or selfish motivations may make us help. Implicitly, we may ask, “What’s in it for me?” There are two major theories that explain what types of reinforcement helpers may be seeking. The negative state relief model (e.g., Cialdini, Darby, & Vincent, 1973; Cialdini, Kenrick, & Baumann, 1982) suggests that people sometimes help in order to make themselves feel better. Whenever we are feeling sad, we can use helping someone else as a positive mood boost to feel happier. Through socialization, we have learned that helping can serve as a secondary reinforcement that will relieve negative moods (Cialdini & Kenrick, 1976).

The arousal: cost–reward model provides an additional way to understand why people help (e.g., Piliavin, Dovidio, Gaertner, & Clark, 1981). This model focuses on the aversive feelings aroused by seeing another in need. If you have ever heard an injured puppy yelping in pain, you know that feeling, and you know that the best way to relieve that feeling is to help and to comfort the puppy. Similarly, when we see someone who is suffering in some way (e.g., injured, homeless, hungry), we vicariously experience a sympathetic arousal that is unpleasant, and we are motivated to eliminate that aversive state. One way to do that is to help the person in need. By eliminating the victim’s pain, we eliminate our own aversive arousal. Helping is an effective way to alleviate our own discomfort.

As an egoistic model, the arousal: cost–reward model explicitly includes the cost/reward considerations that come into play. Potential helpers will find ways to cope with the aversive arousal that will minimize their costs—maybe by means other than direct involvement. For example, the costs of directly confronting a knife-wielding assailant might stop a bystander from getting involved, but the cost of some indirect help (e.g., calling the police) may be acceptable. In either case, the victim’s need is addressed. Unfortunately, if the costs of helping are too high, bystanders may reinterpret the situation to justify not helping at all. We now know that the attack of Kitty Genovese was a murderous assault, but it may have been misperceived as a lover’s spat by someone who just wanted to go back to sleep. For some, fleeing the situation causing their distress may do the trick (Piliavin et al., 1981).

The egoistically based negative state relief model and the arousal: cost–reward model see the primary motivation for helping as being the helper’s own outcome. Recognize that the victim’s outcome is of relatively little concern to the helper—benefits to the victim are incidental byproducts of the exchange (Dovidio et al., 2006). The victim may be helped, but the helper’s real motivation according to these two explanations is egoistic: Helpers help to the extent that it makes them feel better.

Altruistic Help

Photo of an older woman sitting on the sidewalk, reaching in her purse to give money to a monk.

Figure 4. A woman giving alms to a monk in Laos. [Image: Peter Nijenhuis]

Although many researchers believe that egoism is the only motivation for helping, others suggest that altruism—helping that has the improvement of another’s welfareas its ultimate goal —may also be a motivation for helping under the right circumstances. Batson (2011) has offered the empathy–altruism model to explain altruistically motivated helping for which the helper expects no benefits. According to this model, the key to altruism is empathizing with the victim, that is, putting oneself in the shoes of the victim and imagining how the victim must feel. When taking this perspective and having empathic concern, potential helpers become primarily interested in increasing the well-being of the victim, even if the helper must incur some costs that might otherwise be easily avoided. The empathy–altruism model does not dismiss egoistic motivations; helpers not empathizing with a victim may experience personal distress and have an egoistic motivation, not unlike the feelings and motivations explained by the arousal: cost–reward model. Because egoistically motivated individuals are primarily concerned with their own cost–benefit outcomes, they are less likely to help if they think they can escape the situation with no costs to themselves. In contrast, altruistically motivated helpers are willing to accept the cost of helping to benefit a person with whom they have empathized—this “self-sacrificial” approach to helping is the hallmark of altruism (Batson, 2011).

Although there is still some controversy about whether people can ever act for purely altruistic motives, it is important to recognize that, while helpers may derive some personal rewards by helping another, the help that has been given is also benefitting someone who was in need. The residents who offered food, blankets, and shelter to stranded runners who were unable to get back to their hotel rooms because of the Boston Marathon bombing undoubtedly received positive rewards because of the help they gave, but those stranded runners who were helped got what they needed badly as well. “In fact, it is quite remarkable how the fates of people who have never met can be so intertwined and complementary. Your benefit is mine; and mine is yours” (Dovidio et al., 2006, p. 143).

Link to Learning

See this excerpt from the popular TV series Friends episode for a discussion of the egoism versus altruism debate.

Try It

Think It Over

  • The next time you see someone needing help, observe your surroundings. Look to see if the bystander effect is in action and take measures to make sure the person gets help. If you aren’t able to help, notify an adult or authority figure that can.
  • What do you think is the primary motive for helping behavior: egoism or altruism? Are there any professions in which people are being “pure” altruists, or are some egoistic motivations always playing a role?


altruism: a motivation for helping that has the improvement of another’s welfare as its ultimate goal, with no expectation of any benefits for the helper
arousal: cost–reward model: an egoistic theory proposed by Piliavin et al. (1981) that claims that seeing a person in need leads to the arousal of unpleasant feelings, and observers are motivated to eliminate that aversive state, often by helping the victim. A cost–reward analysis: may lead observers to react in ways other than offering direct assistance, including indirect help, reinterpretation of the situation, or fleeing the scene.
bystander effect: situation in which a witness or bystander does not volunteer to help a victim or person in distress
bystander intervention: the phenomenon whereby people intervene to help others in need even if the other is a complete stranger and the intervention puts the helper at risk
cost–benefit analysis: a decision-making process that compares the cost of an action or thing against the expected benefit to help determine the best course of action
diffusion of responsibility: when deciding whether to help a person in need, knowing that there are others who could also provide assistance relieves bystanders of some measure of personal responsibility, reducing the likelihood that bystanders will intervene
egoism: a motivation for helping that has the improvement of the helper’s own circumstances as its primary goal
empathic concern: according to Batson’s empathy–altruism hypothesis, observers who empathize with a person in need (that is, put themselves in the shoes of the victim and imagine how that person feels) will experience empathic concern and have an altruistic motivation for helping
empathy–altruism model: an altruistic theory proposed by Batson (2011) that claims that people who put themselves in the shoes of a victim and imagining how the victim feel will experience empathic concern that evokes an altruistic motivation for helping.
pluralistic ignorance: relying on the actions of others to define an ambiguous need situation and to then erroneously conclude that no help or intervention is necessary
prosocial behavior: social behavior that benefits another person
reciprocal altruism: according to evolutionary psychology, a genetic predisposition for people to help those who have previously helped them.

  1. Manning, Rachel; Levine, Mark; Collins, Alan (September 2007). "The Kitty Genovese Murder and the Social Psychology of Helping: The Parable of the 38 Witnesses". American Psychologist. Washington, D.C.: American Psychological Association. 62 (6): 555–562. CiteSeerX doi:10.1037/0003-066x.62.6.555.
  2. McFadden, Robert D. (April 4, 2016). "Winston Moseley, 81, Killer of Kitty Genovese, Dies in Prison". The New York Times.
  3. A New Look at the Killing of Kitty Genovese: The Science of False Confessions. Association for Psychological Science. (June 2017). Retrieved November 8, 2021, from
  4. "Bystander effect in street disputes disquestioned". Netherlands Institute for the Study of Crime and Law Enforcement. NSCR.NL. 27 March 2019. Archived from the original on May 10, 2019. Retrieved 23 August 2020.