Bystander Effect

Have you ever walked past an unconscious homeless man lying on a busy street? Or maybe you have seen a fight happen in public and decided to ignore it? Often we feel safe in public places because we believe people will help us if something happens to us. However, the bystander effect challenges this idea. In this article, we will investigate why people don't react in emergencies by examining the social psychology of bystander behaviour.

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Table of contents
    • First, we will explore what we mean by the bystander effect in psychology.
    • Then, we will look at the bystander effect definition, explanations of this phenomenon and bystander effect examples.
    • Next, we will take a closer look at bystander effect cases, including the famous case of Kitty Genovese bystander effect.
    • Finally, we will discuss the possible origin of bystander behaviour.

    Bystander behaviour, illustration of a road accident, StudySmarterThe bystander effect explains why people may not help when they see a person in need,

    Bystander effect in psychology

    We know that we are responsible for acting when seeing someone in need of help. However, it's a known phenomenon in psychology that the more people there are witnessing an emergency, the lower the likelihood of someone intervening. This phenomenon, called the bystander effect, can help us understand why people engage or don't engage in prosocial behaviour.

    Prosocial behaviour refers to actions which aim to benefit other people. Helping the person in need would be considered prosocial behaviour when witnessing an emergency. Interestingly, when we find ourselves in a larger crowd, the likelihood of us engaging in this type of prosocial behaviour drops.

    Bystander effect definition

    The term bystander is used to describe a person that witnesses a dangerous situation but doesn't do anything to address it. This behaviour typically occurs when many other people are also present at the scene. The mere presence of others takes the responsibility to act off our shoulders. We become more likely to assume someone else will take care of it and walk away.

    The bystander effect refers to the tendency to remain passive in an emergency, especially if other people around us could act.

    While bystanderism is common, it is also dangerous. If no one feels responsible to act, no one will, putting the victim's life in danger. When bystanders don't take any action, we talk about bystander apathy. If a bystander takes personal responsibility and decides to act to affect the situation positively, we call it bystander intervention.

    Bystander effect examples

    Tom was making unwelcome sexual advances toward a girl at a party. All his friends saw what was happening, but no one felt responsible for talking to Tom and addressing it. Tom's friend, Harry, thought about intervening, but because no one else reacted, he assumed that maybe the situation wasn't that serious. Bystander apathy led to group denial, further discouraging anyone from intervening.

    Another example is Amelia was walking through a crowded city centre with her family when they saw a young man having an epileptic seizure on the pavement. Since many people were around and unfamiliar with the situation, they decided not to intervene. Unfortunately, all the other people thought the same and passed by the man.

    Bystander effects explanation

    Several psychological explanations for bystander behaviour can help us understand this phenomenon and design interventions to minimise it. The two sets of factors that contribute to bystander behaviour include situational and dispositional factors.

    Situational factors

    Situational factors influencing bystander behaviour refer to the environmental influences that promote a lack of action. Since we are more likely to intervene when we are alone than surrounded by others, it can be argued that the presence of others contributes to bystander apathy.

    The presence of others that could act instead of us minimises our personal responsibility to intervene. This is called the diffusion of responsibility.

    Diffusion of responsibility occurs in situations when there is an ambiguity about who should be responsible. For example, if multiple people witness an accident, it might be unclear who exactly should call an ambulance.

    It is important to point at specific people in an emergency to encourage them to act. For example, if we see a person stop breathing, we should point to a person we want to call an ambulance and choose another person to do CPR with us.

    Moreover, we often overvalue the expertise of others, especially in unfamiliar situations; if no one is reacting, then it's probably not a big deal. This leads to pluralistic ignorance, a shared denial about how serious the situation is that legitimises the lack of the group's reaction. While referencing the behaviour and reactions of others is generally helpful, it can also encourage bystander apathy.

    Think about your first day at school or work. In situations that are unfamiliar, we observe others and repeat what they do. Emergencies are rare and unfamiliar for most of us, making us more prone to rely on the judgement of others.

    Latane & Darley (1968) investigated whether the presence and reactions of others will influence bystander apathy in a potentially dangerous situation. The researchers asked participants to complete a questionnaire in a waiting room, where they either sat alone or together with other people. As the participants worked on the questionnaire, the room started to fill up with smoke, indicating a fire in the building. Let's take a look at the findings of this study.

    • Most participants (75%) sitting alone in the room reported the fire within the first two minutes.
    • When participants were accompanied by someone else, only the minority (38%) reported the presence of smoke.
    • Only 10% of participants accompanied by someone who paid no attention to the smoke decided to act.

    This study supports the influence of situational factors (presence of others) on bystander behaviour.

    Another important situational factor is the cost of helping. We will remain passive if we perceive the costs of intervening to be greater than the potential benefits.

    • The costs of intervening involve the time and effort it takes and the possible embarrassment or danger we would expose ourselves to.

    • The benefits of intervening involve feeling better about ourselves, protecting someone from harm, or even saving someone's life.

    Sometimes people don't attempt resuscitation because they are afraid they will embarrass themselves or harm the person rather than help them. This is a distorted view because the person will lose their life if we don't act. In reality, the benefits certainly outweigh the cost of resuscitation.

    The characteristics of the person in need can also affect our judgement of the situation and our likelihood to act. The Piliavin's subway study has demonstrated that people travelling on a subway were less likely to help a person who collapsed if they looked like a drunk but almost always helped a person that looked disabled. Interestingly, the number of other bystanders didn't influence how fast people reacted.

    Bystander behaviour, illustration of a group of people, StudySmarterPeople are less likely to help a person in need when in a crowd,

    Dispositional factors

    Even when many passive bystanders are present, some people still come forward and take the initiative to help. This could be explained by individual personality factors that make some less susceptible to remain passive.

    One dispositional factor influencing bystander behaviour is our perceived expertise, or how competent we think we are to help. If we feel confident with our ability to administer first aid, call for help or confront the attacker, we are more likely to act. However, if we assume that whatever we do won't be successful, we can give up on trying.

    Another important dispositional factor is empathy. According to the empathy–altruism hypothesis, people who are generally less self-focused and more empathetic are more likely to react, despite any situational factors.

    Beirhoff et al. (1991) investigated whether bystanders that help and those that don't help have different personalities. The researchers administered various personality measures to people who performed first aid after witnessing a traffic accident and to passive bystanders. It was concluded that the first aiders' personalities differed on several dimensions, such as:

    • Showed higher empathy and low egocentrism
    • Believed in a just world
    • Had an internal locus of control
    • Emphasised social responsibility

    Similarity to the victim has also been shown to affect bystander behaviour. If the victim is similar to us in terms of demographic characteristics (e.g. age, gender, race) or belongs to the same groups as we do, we are more likely to empathise with this person and intervene.

    Bystander effect cases

    Let's explore the real-life implications of bystander behaviour that highlight why it's important to address it in society.

    Kitty Genovese bystander effect

    The murder of Kitty Genovese is certainly the most famous case of bystander behaviour, sparking a major psychological inquiry into this phenomenon. Kitty was murdered in 1964, at the age of 28. A man attacked her outside of her flat in New York. Kitty was stabbed several times and raped by the man before dying from the injuries she sustained in the attack.

    Shortly after her death, the New York Times published an article claiming that 38 witnesses heard and saw the attack happening but didn't intervene or call for help.

    Can situational or dispositional factors explain the behaviour of bystanders in Kitty's case? One explanation is that none of the 38 witnesses was altruistic, empathetic, or felt competent to stand up to her attacker.

    The second situational explanation would be that the presence of so many other witnesses and their passivity discouraged people from assuming responsibility and intervening.

    Later investigations showed that only a few neighbours heard her screaming and did intervene by scaring the attacker away and calling the police. Unfortunately, no one came to check on Kitty after she was stabbed. She hid at the back of the building, where she was later found by the attacker and brutally killed.

    Bystander behaviour, crime scene illustration, StudySmarterThe case of Kitty Genovese illustrated the bystander effect,

    Even though many details regarding Kitty's murder have been debunked, there are many current cases of bystander behaviour contributing to the victim's death.

    Nowadays, bystanders are also likely to record threatening incidents instead of reacting. This was the case in the killing of Khaseen Morris, a 16-year-old who was attacked by other teenagers in a public space in daylight. Several people are thought to have witnessed and recorded the incident, videos of which were later posted online. None of the bystanders reacted at the time of the attack or called an ambulance to help the teenager.

    Discussion around the origin of bystander behaviour

    Whether altruism and bystander apathy occur due to the influences of nature and nurture is still a matter of discussion. The fact that we are more likely to help victims similar to us supports the nature side of this debate, which argues that we have evolved to protect our kin and promote the survival of our genes.

    On the other hand, reliance on the reactions of others and pluralistic ignorance support the influence of nurture. Social and cultural norms, like the norm of using others as a point of reference, can shape how we act in an emergency. The emphasis on competition in individualistic cultures can also affect how empathetic we feel toward people different to ourselves.

    Most of the research on the bystander effect has been conducted in individualistic cultures. However, it is important to recognise that different factors and mechanisms may guide actions in collectivist cultures.

    Individualistic cultures emphasise the individual's values and goals, while collectivist cultures prioritise the goals and values of the collective.

    Since, in collectivist cultures, it is more acceptable to rely on others, people may base their decisions less on a cost-benefit analysis of the situation and more on the behaviour of other bystanders. In collectivist cultures, people may also be more likely to help strangers, regardless of their similarities.

    Bystander behaviour - Key takeaways

    • The bystander effect refers to the tendency to remain passive in an emergency, especially if other people around us could act.
    • Situational factors affecting bystander behaviour include the presence of others, diffusion of responsibility and the cost of helping.
    • Dispositional factors affecting bystander behaviour include expertise, how empathetic and altruistic we tend to be, and our similarity to the victim.
    • The case of Kitty Genovese's murder has sparked the discussion on bystander behaviour in the psychological community.

    • The mechanisms of bystander behaviour can result from evolution or be a product of social and cultural norms.


    1. Bierhoff, H.W., Klein, R. and Kramp, P. (1991), Evidence for the Altruistic Personality from Data on Accident Research. Journal of Personality, 59: 263-280.
    2. Latane, B., & Darley, J. M. (1968). Group inhibition of bystander intervention in emergencies. Journal of Personality and Social Psychology, 10(3), 215–221.
    3. Piliavin, I., & Rodin, J. (1969). Good samaritanism: an underground phenomenon? Journal of personality and social psychology, 13 4, 289-99 .
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    Frequently Asked Questions about Bystander Effect

    What is the bystander effect?

    The bystander effect refers to the tendency to remain passive in an emergency, especially if other people around us could act.

    Why does the bystander effect occur?

    The bystander effect can occur due to situational factors like the presence of other people or the high cost of helping. It can also be a matter of the personality of the bystander, their level of expertise, empathy or how similar to the victim they are.

    Why is the bystander effect important?

    Bystander apathy can harm or even contribute to the death of the victim.

    Why is the bystander effect unethical?

    Some people may consider not intervening in a situation when someone's life is threatened as unethical.

    What are some modern day examples of the bystander effect?

    The killing of Khaseen Morris, which occurred in 2019. The 16-year-old was attacked by other teenagers in a public space, while the bystanders recorded the incident and never intervened. 

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