The bystander effect, or bystander apathy, is a social psychological phenomenon in which individuals are less likely to offer help to a victim when other people are present. The greater the number of bystanders, the less likely it is that any one of them will help. Several factors contribute to the bystander effect, including ambiguity, cohesiveness and diffusion of responsibility.
Social psychology researchEdit
The bystander effect was first demonstrated in the laboratory by John M. Darley and Bibb Latané in 1968 after they became interested in the topic following the murder of Kitty Genovese in 1964. These 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 staged and researchers measure how long it takes the participants to intervene, if they intervene. These experiments have found that the presence of others inhibits helping, often by a large margin. For example, Bibb Latané and Judith Rodin (1969) staged an experiment around a woman in distress. 70 percent of the people alone called out or went to help the woman after they believed she had fallen and was hurt, but when there were other people in the room only 40 percent offered help.
Variables affecting bystandersEdit
Emergency versus non-emergency situationsEdit
Latané and Darley performed three experiments to test bystander behavior in non-emergency situations Their results indicated that the way in which the subjects were asked for help mattered. In one condition, subjects asked a bystander for his or her name. More people provided an answer when the students gave their name first. In another condition, the students asked bystanders for a dime. When the student gave an explanation, such as saying that their wallet had been stolen, the percentage of people giving assistance was higher (72%) than when the student just asked for a dime (34%). Additional research by Faul, Mark, et al., using data collected by EMS officials when responding to an emergency, indicated that the response of bystanders was correlated with the health severity of the situation.
According to Latané and Darley, there are five characteristics of emergencies that affect bystanders:
- Emergencies involve threat of harm or actual harm
- Emergencies are unusual and rare
- The type of action required in an emergency differs from situation to situation
- Emergencies cannot be predicted or expected
- Emergencies require immediate action
Due to these five characteristics, bystanders go through cognitive and behavioural processes:
- Notice that something is going on
- Interpret the situation as being an emergency
- Degree of responsibility felt
- Form of assistance
- Implement the action choice
Notice: To test the concept of "noticing," Latane and Darley (1968) staged an emergency using Columbia University students. The students were placed in a room—either alone, with two strangers or with three strangers to complete a questionnaire while they waited for the experimenter to return. While they were completing the questionnaire smoke was pumped into the room through a wall vent to simulate an emergency. When students were working alone they noticed the smoke almost immediately (within 5 seconds). However, students that were working in groups took longer (up to 20 seconds) to notice the smoke. Latané and Darley claimed this phenomenon could be explained by the social norm of what is considered polite etiquette in public. In most western cultures, politeness dictates that it is inappropriate to idly look around. This may indicate that a person is nosy or rude. As a result, passers-by are more likely to be keeping their attention to themselves when around large groups than when alone. People who are alone are more likely to be conscious of their surroundings and therefore more likely to notice a person in need of assistance.
Interpret: Once a situation has been noticed, a bystander may be encouraged to intervene if they interpret the incident as an emergency. According to the 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. If it is determined that others are not reacting to the situation, bystanders will interpret the situation as not an emergency and will not intervene. This is an example of pluralistic ignorance or social proof. Referring to the smoke experiment, even though students in the groups had clearly noticed the smoke which had become so thick that it was obscuring their vision, irritating their eyes or causing them to cough, they were still unlikely to report it. Only one participant in the group condition reported the smoke within the first four minutes, and by the end of the experiment, no-one from five of eight groups had reported the smoke at all. In the groups that did not report the smoke, the interpretations of its cause, and the likelihood that it was genuinely threatening was also less serious, with no-one suggesting fire as a possible cause, but some preferring less serious explanations, such as the air-conditioner was leaking. Similarly, interpretations of the context played an important role in people's reactions to a man and woman fighting in the street. When the woman yelled, "Get away from me; I don't know you," bystanders intervened 65 percent of the time, but only 19 percent of the time when the woman yelled, "Get away from me; I don't know why I ever married you."
General bystander effect research was mainly conducted in the context of non-dangerous, non-violent emergencies. A study (2006) tested bystander effect in emergency situations to see if they would get the same results from other studies testing non-emergencies. In situations with low potential danger, significantly more help was given when the person was alone than when they were around another person. However, in situations with high potential danger, participants confronted with an emergency alone or in the presence of another person were similarly likely to help the victim. This suggests that in situations of greater seriousness it is more likely that people will interpret the situation as one in which help is needed and will be more likely to intervene.
Degree of Responsibility: Darley and Latané determined that the degree of responsibility a bystander feels is dependent on three things:
- Whether or not they feel the person is deserving of help
- The competence of the bystander
- The relationship between the bystander and the victim
Forms of Assistance: There are two categories of assistance as defined by Latané and Darley:
- Direct intervention: directly assisting the victim
- Detour intervention. Detour intervention refers to reporting an emergency to the authorities (i.e. the police, fire department)
Implementation: After going through steps 1-4, the bystander must implement the action of choice.
In one study done by Abraham S. Ross, the effects of increased responsibility on bystander intervention were studied by increasing the presence of children. This study was based on the reaction of 36 male undergraduates presented with emergency situations. The prediction was that the intervention would be at its peak due to presence of children around those 36 male undergraduate participants. This was experimented and showed that the prediction was not supported and was concluded as "the type of study did not result in significant differences in intervention."
A meta-analysis (2011) of the bystander effect reported that "The bystander effect was attenuated when situations were perceived as dangerous (compared with non-dangerous), perpetrators were present (compared with non-present), and the costs of intervention were physical (compared with non-physical). This pattern of findings is consistent with the arousal-cost-reward model, which proposes that dangerous emergencies are recognized faster and more clearly as real emergencies, thereby inducing higher levels of arousal and hence more helping." They also "identified situations where bystanders provide welcome physical support for the potentially intervening individual and thus reduce the bystander effect, such as when the bystanders were exclusively male, when they were naive rather than passive confederates or only virtually present persons, and when the bystanders were not strangers."
An alternative explanation has been proposed by Stanley Milgram, who hypothesized that the bystanders′ callous behavior was caused by the strategies they had adopted in daily life to cope with information overload. This idea has been supported to varying degrees by empirical research.
Timothy Hart and Ternace Miethe used data from the National Crime Victimization Survey (NCVS) and found that a bystander was present in 65 percent of the violent victimizations in the data. Their presence was most common in cases of physical assaults (68%), which accounted for the majority of these violent victimizations and less likely in robberies (49%) and sexual assaults (28%). The actions of bystanders were most frequently judged by victims as "neither helping nor hurting" (48%), followed by "helping" (37%), "hurting" (10%), and "both helping and hurting" (3%). Half of the attacks in which a bystander was present occurred in the evening, where the victim and bystander were strangers.
Ambiguity and consequencesEdit
Ambiguity is one factor that affects whether or not a person assists another in need. In some cases of high ambiguity, it can take a person or group up to 5 times as long before taking action than in cases of low ambiguity. In these cases, bystanders determine their own safety before proceeding. Bystanders are more likely to intervene in low ambiguity, insignificant consequence situations than in high ambiguity, significant consequence situations.
Understanding of environmentEdit
Whether or not a bystander intervenes may have to do with their familiarity of the environment where the emergency occurs. If the bystander is familiar with the environment, they are more likely to know where to get help, where the exits are, etc. Bystanders who are in an environment in which they are not familiar with the surroundings are less likely to give help in an emergency situation.
Priming the bystander effectEdit
Research done by Garcia et al. (2002) indicate that priming a social context may inhibit helping behavior. Imagining being around one other person or being around a group of people can affect a person's willingness to help.
Cohesiveness and group membershipEdit
Group cohesiveness is another variable that can affect the helping behaviour of a bystander. As defined by Rutkowski et al., cohesiveness refers to an established relationship (friends, acquaintances) between two or more people. Experiments have been done to test the performance of bystanders when they are in groups with people they have been acquainted with. According to Rutkowski et al., the social responsibility norm affects helping behavior. The norm of social responsibility states that "people should help others who are in need of help and who are dependent on them for it." As suggested by the research, the more cohesive a group, the more likely the group will act in accordance to the social responsibility norm. To test this hypothesis, researchers used undergraduate students and divided them into four groups: a low cohesive group with two people, a low cohesive group with four people, a high cohesive group with two people, and a high cohesive group with four people. Students in the high cohesive group were then acquainted with each other by introducing themselves and discussing what they liked/disliked about school and other similar topics. The point of the experiment was to determine whether or not high cohesive groups were more willing to help a hurt "victim" than the low cohesive groups. The four member high cohesive groups were the quickest and most likely groups to respond to the victim who they believed to be hurt. The four member low cohesive groups were the slowest and least likely to respond to the victim.
Altruism research suggests that helping behaviour is more likely when there are similarities between the helper and the person being helped. Recent research has considered the role of similarity, and more specifically, shared group membership, in encouraging bystander intervention. In one experiment (2005), researchers found that bystanders were more likely to help an injured person if that person was wearing a football jersey of a team the bystander liked as opposed to a team the bystander did not like. However, when their shared identity as football fans was made salient, supporters of both teams were likely to be helped, significantly more so than a person wearing a plain shirt.
The findings of Mark Levine and Simon Crowther (2008) illustrated that increasing group size inhibited intervention in a street violence scenario when bystanders were strangers, but encouraged intervention when bystanders were friends. They also found that when gender identity is salient, group size encouraged intervention when bystanders and victims shared social category membership. In addition, group size interacted with context-specific norms that both inhibit and encourage helping. The bystander effect is not a generic consequence of increasing group size. When bystanders share group-level psychological relationships, group size can encourage as well as inhibit helping.
These findings can be explained in terms of self-categorization and empathy. From the perspective of self-categorization theory, a person’s own social identity, well-being is tied to their group membership so that when a group based identity is salient, the suffering of one group member can be considered to directly affect the group. Because of this shared identity, referred to as self-other merging, bystanders are able to empathize, which has been found to predict helping behaviour. For example, in a study relating to helping after eviction both social identification and empathy were found to predict helping. However, when social identification was controlled for, empathy no longer predicted helping behaviour.
In discussing the case of Wang Yue and a later incident in China, in which CCTV footage from a Shanghai subway showed passengers fleeing from a foreigner who fainted, UCLA anthropologist Yunxiang Yan asserted that the reactions can be explained by deeply seated historical cultural differences in Chinese agrarian society, in which there was a stark contrast between how individuals associated with ingroup and outgroup members, saying, "How to treat strangers nicely is one of the biggest challenges in contemporary Chinese society...The prevailing ethical system in traditional China is based on close-knit community ties, kinship ties." He continued, "A person might treat other people in the person's social group very, very nicely...But turn around, when facing to a stranger, and (a person might) tend to be very suspicious. And whenever possible, might take advantage of that stranger."
Diffusion of responsibilityEdit
Darley and Latané (1968) conducted research on diffusion of responsibility. The findings suggest that in the case of an emergency, when people believe that there are other people around, they are less likely or slower to help a victim because they believe someone else will take responsibility. People may also fail to take responsibility for a situation depending on the context. They may assume that other bystanders are more qualified to help, such as doctors or police officers, and that their intervention would be unneeded. 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. For this reason, some legislations, such as "Good Samaritan Laws" limit liability for those attempting to provide medical services and non-medical services in an emergency.
Organizational ombuds practitioners' researchEdit
A 2009 study published by International Ombudsman Association in the Journal of the International Ombudsman Association suggests that—in reality—there are dozens of reasons why people do not act on the spot or come forward in the workplace when they see behavior they consider unacceptable.
The most important reasons cited for not acting were: the fear of loss of important relationships in and out of the workplace, and a fear of "bad consequences." There also were many reasons given by people who did act on the spot or come forward to authorities.
This practitioners' study suggests that the "bystander effect" can be studied and analyzed in a much broader fashion. The broader view includes not just a) what bystanders do in singular emergencies, b) helping strangers in need, when c) there are (or are not) other people around. The reactions of bystanders can also be analyzed a) when the bystanders perceive any of a wide variety of unacceptable behavior over time, b) they are within an organizational context, and c) with people whom they know. The practitioners' study reported many reasons why some bystanders within organizations do not act or report unacceptable behavior. The study also suggests that bystander behavior is, in fact, often helpful, in terms of acting on the spot to help,and reporting unacceptable behavior (and emergencies and people in need.) The ombuds practitioners' study suggests that what bystanders will do in real situations is actually very complex, reflecting views of the context and their managers (and relevant organizational structures if any) and also many personal reasons.
In support of the idea that some bystanders do indeed act responsibly, Gerald Koocher and Patricia Keith Spiegel wrote a 2010 article related to an NIH-funded study which showed that informal intervention by peers and bystanders can interrupt or remedy unacceptable scientific behavior.
What Would You Do?Edit
John Quiñones' primetime show, What Would You Do? on ABC, tests the bystander effect. Actors are used to act out (typically non-emergency) situations while the cameras capture the reactions and actions of innocent bystanders. Topics include cheating on a millionaire test, an elderly person shoplifting, racism and homophobia.
Non-computer versus computers: computer mediated interventionEdit
Research suggests that the bystander effect may be present in computer-mediated communication situations. Evidence demonstrates that people can be bystanders even when they cannot see the person in distress. In the experiment, 400 online chat groups were observed. One of two confederates were used as victims in each chat room: either a male victim whose screen name was Jake Harmen or a female victim whose screen name was Suzy Harmen. The purpose of the experiment was to determine whether or not the gender of the victim mattered, if the size of each chat group had any effect and if asking for a person's help by directly using their screen name would have any effect. Results indicated that the gender of the victim had no effect on whether or not a bystander assisted the victim. Consistent with findings of Latané and Darley, the number of people present in the chat room did have an effect. The response time for smaller chat groups was quicker than in the larger chat groups. However, this effect was nonexistent when the victim (Suzy or Jake) asked for help from a specific person in the chat group. The mean response time for groups in which a specific person was called out was 36.38 seconds. The mean response time for groups in which no screen name was pointed out was 51.53 seconds. A significant finding of the research is that intervention depends on whether or not a victim asked for help by specifying a screen name. The group size effect was inhibited when the victim specifically asked a specific person for help. The group size effect was not inhibited if the victim did not ask a specific person for help.
Children as bystandersEdit
Although most research has been conducted on adults, children can be bystanders too. A study conducted by Robert Thornberg in 2007 came up with seven reasons why children do not help when another classmate is in distress. These include: trivialisation, dissociation, embarrassment association, busy working priority, compliance with a competitive norm, audience modelling, and responsibility transfer.[jargon] In a further study, Thornberg concluded that there are seven stages of moral deliberation as a bystander in bystander situations among the Swedish schoolchildren he observed and interviewed: (a) noticing that something is wrong, i.e., children pay selective attention to their environment, and sometimes they don't tune in on a distressed peer if they're in a hurry or their view is obstructed, (b) interpreting a need for help—sometimes children think others are just playing rather than actually in distress or they display pluralistic ignorance, (c) feeling empathy, i.e., having tuned in on a situation and concluded that help is needed, children might feel sorry for an injured peer, or angry about unwarranted aggression (empathic anger), (d) processing the school's moral frames—Thornberg identified five contextual ingredients influencing children's behavior in bystander situations (the definition of a good student, tribe caring, gender stereotypes, and social-hierarchy-dependent morality), (e) scanning for social status and relations, i.e., students were less likely to intervene if they didn't define themselves as friends of the victim or belonging to the same significant social category as the victim, or if there were high-status students present or involved as aggressors—conversely, lower-status children were more likely to intervene if only a few other low-status children were around, (f) condensing motives for action, such as considering a number of factors such as possible benefits and costs, and (g) acting, i.e., all of the above coalesced into a decision to intervene or not. It is striking how this was less an individual decision than the product of a set of interpersonal and institutional processes.
Implications of researchEdit
South African murder trialsEdit
In an effort to make South African courts more just in their convictions, the concept of extenuating circumstances came into being. However, no concrete definition of extenuating circumstances was ever made. The South African courts began using the testimony of expert social psychologists to define what extenuating circumstances would mean in the justice system. Examples include: deindividuation, bystander apathy, and conformity. In the case of S. vs. Sibisi and Others (1989) eight members of the South African Railways and Harbours Union were involved in the murder of four workers who chose not to join in the SARHWU strike. Psychologists Scott Fraser and Andrew Colman presented evidence for the defense using research from social psychology. Social anthropologist Boet Kotzé provided evidence for the defense as well. He testified that African cultures are characterized by a collective consciousness. Kotzé testified that the collective conscious contributed to the defendants' willingness to act with the group rather than act as individuals. Fraser and Colman stated that bystander apathy, deindividuation, conformity and group polarization were extenuating factors in the killing of the four strike breakers. They explained that deindividuation may affect group members' ability to realize that they are still accountable for their individual actions even when with a group. They also used research on bystander apathy by Latané and Darley to illustrate why four of the eight defendants watched as the other four defendants killed four men. The testimonies of Fraser and Colman helped four of the defendants escape the death penalty.
Some parts of the world have included laws that hold bystanders responsible when they witness an emergency.
- The Charter of human rights and freedoms of Quebec states that "[e]very person must come to the aid of anyone whose life is in peril, either personally or calling for aid, unless it involves danger to himself or a third person, or he has another valid reason". It is therefore a legal obligation to assist people in danger in Quebec.
- Likewise, the Brazilian Penal Code states that it is a crime not to rescue (or call emergency services when appropriate) injured or disabled people including those found under grave and imminent danger as long as it safe to do so. This also includes abandoned children.
- The German penal code makes it a crime for a person to fail to render aid in cases of accidents or other common dangers, unless such person would thereby endanger themselves or it would be contrary to some other important obligation.
In the US, Good Samaritan laws have been implemented to protect bystanders who acted in good faith. Many organizations are including bystander training. For example, the United States Department of the Army is doing bystander training with respect to sexual assault. Some organizations routinely do bystander training with respect to safety issues. Others have been doing bystander training with respect to diversity issues. Organizations such as American universities are also using bystander research to improve bystander attitudes in cases of rape. Examples include the InterAct Sexual Assault Prevention program and the Green Dot program. Others have been critical of these laws for being punitive and criminalizing the problem they are meant to address.
Many institutions have worked to provide options for bystanders who see behavior they find unacceptable. These options are usually provided through complaint systems—so bystanders have choices about where to go. One option that is particularly helpful is that of an organizational ombudsman, who keeps no records for the employer and is near-absolutely confidential.
The case of Kitty Genovese is often cited and occasionally criticized as an example of the "bystander effect". It is also the case that originally stimulated social psychological research in this area. On March 13, 1964 Genovese, 28 years old, was on her way back to her apartment in Queens, New York, from work at 3am when she was stabbed, sexually assaulted, and murdered in front of multiple witnesses. According to newspaper accounts, the attack lasted for at least a half an hour during which time Genovese screamed and pleaded for help. The murderer attacked Genovese and stabbed her, then fled the scene after attracting the attention of a neighbor. The killer then returned ten minutes later and finished the assault. Newspaper reports after Genovese's death claimed that 38 witnesses watched the stabbings and failed to intervene or even contact the police until after the attacker fled and Genovese had died. This led to widespread public attention, and many editorials. Psychology researchers Latané and Darley attributed the lack of help by witnesses to diffusion of responsibility: because each witness saw others witnessing the same event, they assumed that the others would be taking responsibility and calling the police, and therefore did nothing to stop the situation themselves.
According to an article published in American Psychologist in 2007, the original story of Genovese's murder was exaggerated by the media. Specifically, there were not 38 eyewitnesses, the police were contacted at least once during the attack, and many of the bystanders who overheard the attack could not actually see the event. The authors of the article suggest that the story continues to be misrepresented in social psychology textbooks because it functions as a parable and serves as a dramatic example for students.
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 afterwards at a local hospital.
In October 2011, a 2-year-old girl, Wang Yue, was hit by a small, white van in the city of Foshan, China, then run over by a large truck when she was not moved by bystanders. A total of 18 people ignored her, some going so far as to walk around the blood. The girl was left for seven minutes before a recycler, Chen Xianmei, picked up the toddler and called for help. The child died eight days later.
Reversal of bystander effectEdit
Role of public self-awarenessEdit
In many cases, we believe that individuals like to view themselves as noble by offering help. This concept is related to the notion of self-awareness. If it is true that people focus on the impression they make on others, then public-awareness through the use of accountability cues can stimulate people to give help to each other. However, being surrounded by a lot of bystanders does not automatically create public self-awareness. In fact, in some cases being surrounded by bystanders allows an individual to hide within the crowd and feel anonymous. According to Dr. van Bommel, by introducing an accountability cue, the aim is to eliminate feelings of anonymity and increase the likelihood of them offering help.
To investigate if people would help others in the presence of bystanders alone or when introducing an accountability cue, van Bommel set out to perform two experiments. For the first experiment, participants were invited to join an online forum. A sample of 86 students was used and in the forum participants saw their own name and the names of the other people that were online in the left upper half of the screen. To operationalize the accountability cue, participants' names were displayed in either red or black. Red (salient condition), utilized to attract attention and stand out, was used to raise public self-awareness while black (non-salient) was used for participants to have the same color as other bystanders. In random order, five different messages were presented to the participants. Each of these messages was a personal story of a person in distress. The number of responses a participant typed measured the helping behavior from participants and as expected, the results showed that names in black (non-salient condition) were linked to the bystander effect with the amount of help being 2. However, when names were in the red (salient condition), the bystander effect was reversed with the amount of help being 3. This exemplifies the role of self-awareness in the reversal of bystander effect.
In order to further investigate the reversal of the bystander effect, van Bommel performed a second experiment, also reported in the article, with a sample size of 111 students. Unlike the first study, they wanted all participants in the forum to be indistinguishable from other bystanders on the forum. Therefore, the manipulation of public self-awareness was induced independently from the Internet forum. The procedure was identical to the first study, with a few variations. To induce public awareness in this study, webcams were mounted on participant’s computers. Participants could not see the video feed, but to make this more salient, they asked participants before they started to check whether the camera was on by looking at a LED-indicator underneath the webcam. To make the conditions resemble each other as close as possible, they asked participants in the camera absent condition to check if the LED-indicator for Num-Lock was on. Similar to the first experiment, five different messages were presented to the participants and the number of responses a participant typed measured the helping behavior from participants. Once again, the results were as expected. When the camera was not present, the bystander effect existed with the average amount of help being 1.5. However, when a camera was present, the bystander effect was reversed with the amount of help doubling to 3. That said, the findings revealed the importance of public self-awareness in the bystander effect.
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- Thornberg, R (2007). "A classmate in distress: schoolchildren as bystanders and their reasons for how they act". Social Psychology of Education. 10: 5–28. doi:10.1007/s11218-006-9009-4.
- Thornberg, Robert (2010). "A student in distress: Moral frames and bystander behavior in school". Elementary School Journal. 110 (4): 585–608. doi:10.1086/651197.
- Colman, A.M. (1991). "Crowd psychology in South African murder trials". American Psychologist. 46 (10): 1071–1079. doi:10.1037/0003-066x.46.10.1071.
- Charter of human rights and freedoms Section 2
- "DEL2848". Planalto.gov.br. Retrieved 2011-10-27.
- §323c StGB (the German criminal code)
- Scully, M.; Rowe, M. (2009). "Bystander training within organizations". Journal of the International Ombudsman Association. 2 (1): 1–9.
- See also http://www.clemson.edu/olweus/ for an overview of a use of the Olweus Bullying Prevention Program.
- Ahrens, C. E.; Rich, M. D.; Ullman, J. B. (2011). "Rehearsing for real life: The impact of the InterACT sexual assault prevention program on self-reported likelihood of engaging in bystander interventions". Violence Against Women. 17 (6): 760–776. doi:10.1177/1077801211410212.
- Coker, A. L.; Cook-Craig, P.; Williams, C. M.; Fisher, B. S.; Clear, E. R.; Garcia, L. S.; Hegge, L. M. (2011). "Evaluation of green dot: An active bystander intervention to reduce sexual violence on college campuses". Violence Against Women. 17 (6): 777–796. doi:10.1177/1077801211410264.
- Meyer, Doug. "The Gentle Neoliberalism of Modern Anti-bullying Texts: Surveillance, Intervention, and Bystanders in Contemporary Bullying Discourse". Sexuality Research & Social Policy.
- 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. 62 (6): 555–562. doi:10.1037/0003-066x.62.6.555. PMID 17874896.
- DARLEY, JOHN M.; LATANE, BIBB. "BYSTANDER INTERVENTION IN EMERGENCIES: DIFFUSION OF RESPONSIBILITY". Journal of Personality and Social Psychology. 8 (4, Pt.1): 377–383. doi:10.1037/h0025589.
- Manning, R.; Levine, M.; Collins, A. (2007). "The Kitty Genovese murder and the social psychology of helping: The parable of the 38 witnesses" (PDF). American Psychologist. 62 (6): 555–562. doi:10.1037/0003-066X.62.6.555. PMID 17874896.
- Many issues about this incident are disputed. Roughly one year after the incident, Raymond Zack's family filed a "Failure of Duty" lawsuit against the City of Alameda and the County of Alameda.
- Alameda police released redacted police reports to the media after the event that confirm this.
- "Alameda Police Release Memorial Day Drowning 911 Calls". San Francisco. 2011-06-08.
- "The Death of Raymond Zack: No Heroes, Only Bystanders". 2011-06-01.
- "Such callous disregard for life". Orange County. 2011-06-10.
- "Chinese toddler run over twice after being left on street". London: Telegraph. 2011-10-17. Retrieved 2011-10-27.
- Oct 22, 2011 5:03 PM ET (2011-10-22). "The bystander effect—Canada—CBC News". Cbc.ca. Retrieved 2011-10-27.
- Bommel, M.V.; et al. (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. doi:10.1016/j.jesp.2012.02.011.