This rate dropped to over 60 percent when they believed two other people were present and to less than half when they thought five others were present. The time it took to offer help also varied: less than a minute when alone, but almost three minutes on average with five others.
This was initially attributed to a diffusion of responsibility—people felt less personal responsibility to act when others were present. Subsequent replications and studies across various emergencies confirmed the bystander effect, demonstrating that people often walked by someone in need without helping.