Journal of Personality and Social Psychology

Ss overheard an epileptic seizure. They believed either that they alone heard the emergency, or that 1 or 4 unseen others were also present. As predicted the presence of other bystanders reduced the individual's feelings of personal responsibility and lowered his speed of reporting (p < .01). In groups of size 3, males reported no faster than females, and females reported no slower when the 1 other bystander was a male rather than a female. In general, personality and background measures were not predictive of helping. Bystander inaction in real-life emergencies is often explained by apathy, alienation, and anomie. This experiment suggests that the explanation may lie more in the bystander's response to other observers than in his indifference to the victim.

Bystander intervention in emergencies: Diffusion of responsibility.