The more bystanders present, the less likely anyone helps in an emergency.
Verdict: mixed
The lab effect is real, but real-world CCTV shows someone intervenes in the large majority of public conflicts.
What the evidence shows
Darley & Latané (1968), spurred by the Kitty Genovese murder, showed in the lab that people are slower to respond to an emergency when others are present — responsibility feels diffused. The finding is one of social psychology's most robust and has been replicated many times.
But a study of actual street conflicts using CCTV from three countries (Philpot et al., 2020) found that in 90% of incidents at least one bystander intervened, and more bystanders meant a higher chance that someone helped. So both things are true: adding bystanders can lower each individual's probability of acting, yet in real public emergencies the sheer number of people usually means help does arrive. The pessimistic 'no one will help in a crowd' takeaway is not supported.
Sources
Darley, J. M., & Latané, B. (1968). Bystander intervention in emergencies: Diffusion of responsibility.
Journal of Personality and Social Psychology, 8(4), 377–383
Participants who believed others were present were slower and less likely to respond to a staged emergency.
DOI: 10.1037/h0025589 →Philpot, R., Liebst, L. S., Levine, M., Bernasco, W., & Lindegaard, M. R. (2020). Would I be helped? Cross-national CCTV footage shows that intervention is the norm in public conflicts.
American Psychologist, 75(1), 66–75
In real CCTV-recorded conflicts, at least one bystander intervened in 90% of cases, and larger groups raised the odds of help.
DOI: 10.1037/amp0000469 →