The Bystander effect: a closer look at why we fail to help

Place yourself in a crowded public space – perhaps a mall, a park, or a farmer’s market. You witness someone suddenly fall. You might assume that someone else will step in to help. But what happens when everyone around you has the same thought? This illustrates the bystander effect, a phenomenon in which people become less likely to offer help when others are present, demonstrating how social situations can influence behaviour.

A famous real-life incident led to the bystander effect becoming widely studied in the years that followed. After the murder of Kitty Genovese in 1964 in New York City, the media reported that countless witnesses had seen or heard the attack, though no one intervened or called the police. Although these reports were later found to be inaccurate, this case sparked discussion about understanding why people sometimes fail to help when others are around.

Since the murder of Kitty, the bystander effect has become a key area of research in social psychology. In 1968, Darley and Latané (1968) investigated this phenomenon. Participants sat in a room alone and communicated via an intercom system, believing they were participating in a discussion with either one, two, or five other individuals. In reality, each session involved only one real participant, while the other voices were pre-recorded. During the discussion, a confederate, presented as another student, suffered a fake seizure. Darley and Latané measured how quickly the participant left the room and reported the emergency. When students believed they were the only one present during the seizure, they reported the emergency 85% of the time. In contrast, when they believed other individuals were also present during the seizure, that number dropped to 31%. This finding suggests that when more people are present during an emergency, individuals are less likely to intervene, highlighting that the behaviour of helping is determined by social and situational factors. From these findings, the researchers identified three processes that may contribute to the bystander effect: diffusion of responsibility, the idea that individuals divide responsibility among those present; evaluation apprehension, the fear that someone’s action will be judged; and pluralistic ignorance, the tendency to look to others who are also not taking action and use that as a reason to not intervene.

The bystander effect extends beyond face-to-face interactions and can also occur online, where it is known as the digital bystander effect. Digital bystanders are individuals who witness harmful or concerning behaviour on digital platforms and fail to intervene. Diffusion of responsibility is also present online, though users believe the platform, not another person, will mediate the issue when needed. Research by Davidovic (2026) highlights barriers to intervening in digital spaces, including fear of becoming a victim themselves or making things worse for the victim by intensifying the issue at hand. Davidovic’s research identified recommendations to reduce these barriers and increase intervention via simulation studies, such as normalising and encouraging bystander intervention through community rule pop-ups or advertisements.

All in all, the bystander effect illustrates how social influence and perceived responsibility can shape behaviour. Becoming aware of these psychological processes can make a difference: instead of assuming someone else will intervene, individuals can recognise their responsibility and choose to actively help in a situation. However, awareness alone is not enough. Addressing these barriers through education that fosters confidence and social norms that value intervention is just as important as encouraging individual responsibility. 

Written by Shreya Dhaliwal

Related articles: The halo effect / The endowment effect / Loss aversion

REFERENCES

Asnicar, S. (2025, August 20). The 5 D’s of bystander intervention - online training. Active Bystander Training. https://bystandertraining.com.au/the-5ds-of-being-an-active-bystander/.   

Darley, J. M., & Latane, B. (1968). Bystander intervention in emergencies: Diffusion of responsibility. Journal of Personality and Social Psychology, 8(4, Pt.1), 377–383. https://doi.org/10.1037/h0025589.   

Davidovic, A. (2026, April 15). Scroll on or step in – the digital bystander dilemma. Centre for Research and Evidence on Security Threats. https://crestresearch.ac.uk/comment/scroll-on-or-step-in-the-digital-bystander-dilemma/.  

Jarry, J. (2025, October 3). The bystander effect started from a lie. McGill Office for Science and Society. https://www.mcgill.ca/oss/article/critical-thinking-history/bystander-effect-started-lie   

Medium. (2024, November 20). Understanding the bystander effect. https://medium.com/@p.o.e.speaks/understanding-the-bystander-effect-why-do-we-wait-for-someone-else-to-act-even-when-help-is-6913b774a295. 

Scott, E. S., Ross, D. A., & Fenstermacher, E. (2021). Stand by or stand up: Exploring the biology of the bystander effect. Biological Psychiatry, 90(2). https://doi.org/10.1016/j.biopsych.2021.05.007.