Screams tore through the early morning silence of Queens, New York. Lights flickered on in nearby windows. Curtains shifted. 28 year old Kitty Genovese was witnessed by nearly 40 individuals being brutally attacked, stabbed and raped to death. And yet, while the attacker returned twice over the next 30 minutes, no one intervened until it was too late. This chilling murder case of 1964 didn’t just shock the nation – it exposed a deeply unsettling truth about human nature, giving rise to what psychologists would later call the bystander effect.
Coined by psychologists John Darley and Bibb Latané, the bystander effect refers to the phenomenon in which individuals are less likely to help someone in distress when others are present. We like to believe that we are naturally inclined to help – that in an emergency, we would act without hesitation. However, Darley and Latané’s research in 1968 revealed otherwise. In their study, participants who believed they were the only witnesses to an emergency scenario intervened nearly every time. But when they believed others were also present, only 62% chose to help (Darley, Latané, 1968).
Subsequent studies of the bystander effect have been extended to non-emergency situations. For example, people in groups are less likely to report a malfunctioning camera being used in a scientific study (Misavage & Richardson, 1974), help pick up dropped pencils or coins (Latané & Dabbs, 1975), answer the door (Levy et al., 1972), and stop to help a stranded motorist (Hurley & Allen, 1974). This significant reduction in helping behavior highlighted how the presence of others can alter rational behaviour of individuals. Upon further experimentation, the two psychologists eventually summarized the reasoning behind such irrational behavior down to 3 key points: diffusion of responsibility, evaluation apprehension and pluralistic ignorance.
Diffusion of Responsibility
The Diffusion of responsibility refers to the tendency to refrain from helping others when others are present due to the reduced sense of personal accountability. Therefore, as the size of the crowd increases, the moral burden one feels lowers accordingly as individuals believe someone else will rise up to the occasion. Not only does the bystander believe that the moral obligation falls upon the collective group, it also believes that the blame for not helping can be shared instead of accusing a single individual. In Kitty Genovese’s case, when the neighbors were asked why they did not intervene or call the police earlier, some answers were “I didn’t want to get involved”; “Frankly, we were afraid”; “I was tired. I went back to bed.” (New York Times, 1964). These rationalizations highlight how individuals unconsciously transfer moral burden to the collective.
Evaluation Apprehension
Evaluation apprehension refers to the fear of being negatively judged by others when acting publicly if they have misinterpreted the situation. According to prospect theory, individuals weigh potential losses more heavily than equivalent gains when making decisions under uncertainty. Thus, people might be more sensitive to the possible costs of intervening, like embarrassment if they misread the situation, the risk of personal harm, or even legal entanglements, than to the benefits of helping, like potentially saving a life. The presence of other bystanders intensifies this fear: with more eyes watching, the social pressure to not “overreact” or misstep increases, further tipping the scale toward inaction.
Pluralistic Ignorance
Pluralistic ignorance occurs when individuals look to others to gauge whether help is needed in an uncertain situation. If everyone appears calm or inactive, each person assumes there is no real emergency. This misreading is reinforced by the status quo bias, which is the tendency to stick with the current state of affairs (Samuelson and Zeckhauser, 1988). In ambiguous moments, doing nothing feels safer than taking potentially unnecessary action. Anchoring further intensifies this effect: when no one reacts, that inaction becomes the reference point for interpreting the situation and therefore, if others aren’t alarmed, the bystander concludes that there is no cause for concern (Tversky and Kahneman, 1974).
We can also compare this effect with a concept in game theory known as the volunteer’s dilemma. In this scenario, the group benefits if at least one person acts. However, since action comes with personal cost, no one might choose to step up, resulting in everyone suffering (Diekmann, 1985). This is because individuals may consciously or subconsciously assume a passive role, hoping someone else will intervene and still reap the benefit of the positive outcome, acting as free riders in this scenario by not personally incurring the cost. If more people are present, it becomes more tempting to fade into the crowd and let others shoulder the moral responsibility. The bystander effect, then, is not just a social illusion but a game-theoretic trap where self-interest undermines group welfare.
From a neurobiological perspective, researchers have looked at the regions of the brain that facilitate helping behavior – the pre and postcentral gyrus, and the medial prefrontal cortex- and found that as the number of bystanders increases, the activity in these parts of the brain decreases. (Hortensius & de Gelder, 2014). Helping behavior appears to be “reflexive,” governed by the tension between initial fear and rising sympathy (Rand, 2016; Zaki and Mitchell, 2013). Whether a person acts or not depends on which emotional impulse prevails.
Thus, the bystander effect exposes a paradox at the heart of human social behavior. However, as we can see it isn’t always a matter of cowardice, but rather the result of complex social dynamics and psychological processes. However, in a world where inaction can be fatal, recognizing and resisting these forces isn’t just brave – it’s necessary.
References:
Darley, J. M., & Latané´, B. (1968). Bystander intervention in emergencies: Diffusion of responsibility. Journal of Personality and Social Psychology, 8, 377–383.
Diekmann, A., 1985. Volunteer’s dilemma. Journal of Conflict Resolution, 29(4), pp.605–610.
Hortensius, Ruud, & De Gelder, Beatrice. (2018). From Empathy to Apathy: The Bystander Effect Revisited. Current Directions in Psychological Science, 27 (4), 249-256.
Hurley, J.R. and Allen, B.P., 1974. Helping behavior in car breakdown situations. Journal of Social Psychology, 94(2), pp.287–288.
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. and Dabbs, J.M., 1975. Sex, group size and helping in three cities. Sociometry, 38(2), pp.180–194.
Levy, M., Freitas, A. and Adams-Webber, J., 1972. Helping behavior in response to a doorbell. Psychological Reports, 30(1), pp.247–250.
Misavage, R. and Richardson, D.R., 1974. Effect of group size and ambiguity of the situation on helping behavior. Journal of Personality and Social Psychology, 10(1), pp.139–146.
New York Times, 1964. 37 Who Saw Murder Didn’t Call the Police. [online] Available at: https://www.nytimes.com/1964/03/27/archives/37-who-saw-murder-didnt-call-the-police.html [Accessed 27 April 2025].
Samuelson, W. and Zeckhauser, R., 1988. Status quo bias in decision making. Journal of Risk and Uncertainty, 1(1), pp.7–59.
Tversky, A. and Kahneman, D., 1974. Judgment under uncertainty: Heuristics and biases. Science, 185(4157), pp.1124–1131.
Tversky, A. and Kahneman, D., 1979. Prospect theory: An analysis of decision under risk. Econometrica, 47(2), pp.263–291.
Zaki, J. and Mitchell, J.P., 2013. Intuitive prosociality. Current Directions in Psychological Science, 22(6), pp.466–470.
B.BIAS 